Regular readers know I love me my gamma-ray bursts: the most titanic and violent explosions the Universe is capable of producing. If one were to occur within a few thousand light years of the Earth, it would sterilize our planet down to the base of the crust.
Happily for us, all GRBs happen very far away. And on September 13th, NASA’s Swift satellite saw what has turned out to be the most distant GRB ever detected: the light from the massive star that died and created the burst traveled 12.8 billion light years to reach us.
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| A combination of Swift’s ultraviolet and X-ray views of GRB 080913, the most distant burst ever seen so far. |
That means the Universe was only a little over 800 million years old when the star died, which in turn means the star itself was among the first in the Universe to be born; the first stars were formed about 400 million years earlier. The star probably only lived a few scant million years before detonating, catastrophically tearing itself to shreds at the end of its life, and releasing as much energy in a few seconds as the Sun will over its entire 10 billion year lifetime. For a few seconds the dying star was the single brightest object in the Universe, but over the intervening eons as its roar traveled across the cosmos it faded to whisper, eroded by its travel, literally fighting against the expansion of space itself.
Almost 13 billion years after the event, that whisper was detected by Swift, and the coordinates quickly relayed to the ground, where follow-up observations were rapidly produced. Within hours, spectra taken using a monster 8-meter telescope in Chile revealed the terrible distance to the burst (for those who like details, the redshift of the burst was measured at a record-breaking 6.7). This shattered the previous record holder, which was 70 million light years closer to us when it blew up.
The burst was so distant that the optical light emitted by the explosion had been redshifted into the infrared, and even then it was amazingly faint, less than a millionth as bright as what our eyes can detect (even if we could see in the IR, which we can’t). They say time heals all wounds, but sometimes vast distances can do the trick as well.
Probing ever further into the Universe is a rich field for astronomy. We learn more about the behavior of objects back then; how they lived, how they died, and in what environment they spent the intervening years. The heavy elements created in those far-distant explosions eventually became us: the iron in your blood and the calcium in your teeth were created in supernovae and gamma-ray burst explosions billions of years ago. When you look at the picture of that terribly-removed explosion, remember that you’re almost literally looking in a mirror.
And need I remind you? Chapter 4 of Death from the Skies! has everything you’ve ever wanted to know about GRBs in it, including what would happen if one were to go off too close to us for comfort.
September 19th, 2008 at 3:48 pm
Dr. Phil Plait:
According to Wikipedia, only half the Earth would be sterilized:
September 19th, 2008 at 3:50 pm
Pretty clever of you to go back in time to arrange this just in time for your book release. I guess watching all that Dr. Who has finally paid off. Though I wonder….I’m reminded of an Arthur C. Clarke short story called “The Star” in which an exo-archaeologist (or someone doing something like that) discovers the remains of an ancient, advanced civilization that happened to live on a planet orbiting a star which God in his infinite mercy and wisdom, decided to make go nova as a birth announcement for a bouncing baby Jesus. Phil, I just hope you chose a star system devoid of life.
September 19th, 2008 at 4:17 pm
Of course we know nothing about what actually produced this burst of gamma rays, or how whatever-the-hell-it-was produced them. Phil asserts with utmost confidence that it was an early star demolishing itself, but if he wished to be honest he could point out that he’s totally just guessing.
September 19th, 2008 at 4:28 pm
Phil, I have read before that only galaxies very far from us (and therefore distant in the past) have GRBs. I have also heard that galaxies with stars deficient in metals are the most likely candidates for GRBs. Assuming these are both true statements, I come to the following conclusion: GRB’s must come from galaxies that are very young and formed in the early stages of the universe (and consequently that’s why they are so many billions of light years away) Since metals and other elements are formed from supernova explosions, only very young galaxies that have had little element formation due to supernovae have a high potential for GRBs. Is that reasoning basically correct?
September 19th, 2008 at 4:31 pm
… not that there’s anything wrong with that. (Honesty, I mean.)
September 19th, 2008 at 4:36 pm
Actually Nathan who would notice a link to Nasa’s press release stating just what Dr Plait is saying.
September 19th, 2008 at 4:37 pm
One thing that’s always irked me, and perhaps Phil would in his great wisdom humbly explain, is how we got here so much faster than the light did. Assuming we all started in the same place 13.7 bya, how did we 12.8 billion light years away from the GRB in only 800 million years (the age of the universe when the GRB occurred)?
September 19th, 2008 at 4:59 pm
@Nathan: it would seem that your strong, sweeping assertions have become a little more caustic but less substantive … “Of course we know nothing”, “but if he wished to be honest he could point out that he’s totally just guessing”, for example.
In the case of GRBs, do you have have anything specific or concrete to offer, wrt inconsistencies between the observations and models (hypernovae, core collapse stars, etc)?
More generally, it seems there’s a gulf between your understanding of the nature of astrophysics and Phil’s (and, indeed, others who have written comments).
Oh, and may I ask if you intend to answer the questions I asked you, earlier?
September 19th, 2008 at 5:01 pm
Denial (also called abnegation) is a defense mechanism postulated by Sigmund Freud, in which a person is faced with a fact that is too uncomfortable to accept and rejects it instead, insisting that it is not true despite what may be overwhelming evidence.
September 19th, 2008 at 5:09 pm
…square…star…diamond, not in the rough…it’s….
…sorry, I got distracted by the object at the bottom.
These are all warning shots, you know. That Large Hadron Collider is going to cause all sorts of Quantum Polytemporal Parawhoozits, mark my words. You think the universe is just gonna let us do what we want without invoking some sort of Exclusion Principle?
(Hat tip to Larry Niven for the short story “Rotating Cylinders and the Possibility of Global Causality Violation”, which reveals why nobody who has successfully designed a time machine has gotten a chance to use it.)
September 19th, 2008 at 5:15 pm
Ryan,
Short answer is we didn’t.
As I understand it, we were a lot closer than 12.8 billion light years when the GRB occurred
However, in the intervening time the universe has expanded, so the light has now travelled 12.8 Billion light years to reach us. This expansion of the universe is why the light it now so red shifted.
September 19th, 2008 at 5:21 pm
I remember some years back talking (in grad school) about what could be at the heart of a GRB because we really didn’t know what they were. Now we’re talking about bagging them almost as soon as they explode… progress is wonderful!
September 19th, 2008 at 5:30 pm
Nathan,
So we should take the word of a PhD student in Arachnid systematics over the word of an actual PhD in Astronomy as regards to the formation and cause of GRBs why exactly? I mean, if I had a question about Arachnids I would almost certainly place your knowledge ahead of Dr. Plaits but as regards to observed phenomena in the field of Astronomy… well, I think I’ll take the good Dr.’s word over yours any day of the week and twice on Sunday.
It does of course help that Phil is backed up by a wealth of observational data regarding GRBs and their aftermath that have lead to very good theories of why and how GRBs occur. Look up collapsar if you want the gory details on the currently prevailing model - which just happens to be strongly supported by current observational evidence and is therefore treated provisionally as fact. At least until, as in all science, a better model can be found that matches the data. So, we do actually have a pretty good idea of where GRBs come from.
For the sake of completeness there is another type of GRB - called a Short GRB (<2sec burst) that appears to have a different cause. One of the best theories for these Short GRBs is a collision between 2 neutron stars though the evidence for this process is much less conclusive than that for collapsar driven GRBs. The main issue with the neutron star collision theory is that, in the short GRBs that have been studied, there is a lack of expected effects of gravitational waves that are predicted by the model…. so the jury is still out on Short GRBs. The regular kind of GRB science has pretty well nailed down though.
September 19th, 2008 at 6:09 pm
Pretty cool, Phil!
I recall when I thought that supernova were the surpreme explosion of nature. Is there some comparison to how much brighter or more powerful a GRB is than a supernova? For an example, say a typical Type 1a supernova compared to the average GRB as seen here.
September 19th, 2008 at 6:09 pm
YAY, GRB!!!! WOOOOOOO!!!!
September 19th, 2008 at 6:13 pm
If Halton Arp is right and redshift has nothing to do with distance , such anomalies can be easily explained without resorting to highly contrived schemes to produce this energy output.
.
September 19th, 2008 at 6:20 pm
Mike, very big if there.
September 19th, 2008 at 6:23 pm
Extract from Wikipedia:
September 19th, 2008 at 6:36 pm
ERRATUM: That should be 10^46 joules, not 1046 joules.
September 19th, 2008 at 6:47 pm
@MIke: what test do you think could be applied, to tell if Arp is right? And do you have a list of the observations - like lensed quasars - that seem difficult (shall we say) to explain in any way other than by the (redshift-distance) Hubble relationship?
September 19th, 2008 at 7:24 pm
If Halton Arp is right and redshift has nothing to do with distance , such anomalies can be easily explained without resorting to highly contrived schemes to produce this energy output.
Why exactly is the currently accepted theory of GRBs a “highly contrived scheme” compared to Arp’s galactic nocturnal emissions theory?
September 19th, 2008 at 7:45 pm
I was unclear on this, so I looked it up.
So just a quick explanation of what “the redshift of the burst was measured at a record-breaking 6.7″ means: Cosmological redshift is caused by the expansion of space between an object and an observer. This is expressed as a ratio of the wavelengths at the observer and at the object minus one. z = λ(now) / &lambda(then) -1. So for a redshift of 6.7, even assuming a low-energy gamma ray (some would consider it a high-energy X-ray) of 10 pm (1 picometer is one trillionth of a meter) wavelength, it would still have a wavelength of 77 pm, so it’s still a very high energy photon, but at the distance, the beam has spread out and so is much, much dimmer.
For comparison, violet light is in the range of 380 to 450 nm (1 nanometer is one billionth of a meter), so even the shortest wavelength we can normally see with our eyes is still about 4,500 times longer than the redshifted gamma ray described above. This is like comparing the altitude that the Space-X prize winners had to achieve to the distance to the Moon.
Hope my HTML and my math are all good.
September 19th, 2008 at 7:46 pm
Crap. That should be: z = λ(now) / λ(then) - 1
September 19th, 2008 at 9:17 pm
>>such anomalies can be easily explained
What anomalies would that be? Usually the word “anomaly” used in the context it was used by MIke is a warning for “Here be Woo!” However, giving him the benefit of the doubt here…
An anomaly is something that appears to be a difference or exception to a generally accepted rule or expectation. What is anomalous in this GRB?
September 19th, 2008 at 11:49 pm
@Stark: I probably know even less about arachnids than you do. I do happen to like Chris’s blog.
@DRD: Do you pretend to know what exactly produces these gamma-ray bursts, and how they go about doing it? It’s one thing to imagine a process that might release enough energy, and entirely another to demonstrate that such a process is actually doing it in this case. In a real science, your colleagues would expect the latter.
September 20th, 2008 at 12:15 am
@Jay,
Actually Ryan’s question has had me thinking now…
So, has the light finally caught up to us because the expansion has slowed down? Maybe Phil could cover this in a post?
September 20th, 2008 at 1:54 am
Three questions :
1) Is there anything in the spectrum (or elsewhere?) of this Gamma-Ray Burst event to indicate its a Population III (first ever generation) star?
2) Are there any sign its one of those rare particle-anti-particle (correct term?) hypernova type supernova which theoretically happen and leave absolutelynothing left of their precursor stars.
(Eta Carinae is apparently a possible candidate for that SN type.)
3) Did the Fermi (ex-GLAST) space Observatory detect this event as well and have they corroborated or added anything to our understanding of it?
Anyone care to enlighten us on the answers to these?
Whatever the answers :
CONGRATULATIONS SWIFT & team! Well done!
September 20th, 2008 at 2:01 am
Wish icould edit here.
2) Should read :
“Are there any signs or evidence that this was one of those rare particle-anti-particle (correct term?) hypernova type supernova which theoretically happen to ultra-massive (100 Plus solar mass) stars and leave absolutely nothing left of their precursor stars -no black goles or neutron stars.
(Eta Carinae is apparently a possible candidate for that SN type.)
Can we tell what the spectral class & lumninosity type(s) were - massive B-type supergiant like Sanduleak {numerals} or red supergiant like Betelgeux or colliding white dwarfs or fusing binary pulsars …. or can we at
least rule any of them out?
September 20th, 2008 at 2:10 am
@ Stark :
“The main issue with the neutron star collision theory is that, in the short GRBs that have been studied, there is a lack of expected effects of gravitational waves that are predicted by the model…. so the jury is still out on Short Gamma Ray Bursts”
Have any gravitational waves from anything ever been detected?
Are gravitational waves known from any solid facts or are they just inferred by orbital dynamics? Not knocking them mind, just unsure if we’ve got anything other than reasonable hypothesis on them.
PS. Have you read the eponymous book by Ben Elton, Stark Its pretty good!
PPS Asked before but haven’t seen answered - is it recomended practice / usual custom / correct netiquette to put posters names inbold when responding to them? I’m not sure, am trying to do the right thing here.
September 20th, 2008 at 2:13 am
Nathan said Do you pretend to know what exactly produces these gamma-ray bursts, and how they go about doing it?
That’s the begging the question logical fallacy isn’t it or is it a loaded question? Do you still beat your wife?
Do you know what a GRB is? Can you demonstrate it?
Galactic morse code is what I think it is. That was a dit. More dahs and dits to follow.
September 20th, 2008 at 2:44 am
Sick.
September 20th, 2008 at 2:51 am
Shane asked :
“Do you still beat your wife?”
Yes! Quite regularly - at chess that is!
Mind you she beats me at footy so there we go ..
The Bad Astronomer headlined Swift discovering the Titantic explosion. But, hang on, that’s gotta be wrong! The Titanic didn’t explode - it sank!
… Although it did break in half as it was sinking - if that counts? Plus I think the maths is a bit off, Titanic was 1912 - ninety six (light?) years ago NOT twelve billion!
September 20th, 2008 at 2:56 am
BTW Whats the Creationist / I.D. positionon Gamma ray Bursts -what does that mob think they are?
* Crickets *
*crickets *
*More crickets *
* Head scratching noise *
ID~iot Creationist : “Ow I got a splinter in my finger!!”
* still more crickets *
ID~iot Creationist : Er … Umm … God farting?
September 20th, 2008 at 3:15 am
Of course this GRB has been discussed for over a week already on your own forum, Phil
Wish you’d be able to join the discussions there more often..
September 20th, 2008 at 4:56 am
@Michael L
Interesting question.
But no, the light hasn’t finally caught up with us because the expansion of space has slowed down.
Infact it seems the rate of expansion is actually increasing (google for ‘dark energy’)
Here’s my thought experiment which may or may not be near the mark:
Think back to the event itself and the much smaller universe of the time.
As the light makes it’s journey towards us, space is stretched, but the light is always getting closer to us. Now it has arrived and although it’s taken 12.8 billion years to reach us it hasn’t actually travelled 12.8 billion light years but significantly less.
I, too, would be interested in hearing a better explanation of this from someone who knows what they are talking about….
September 20th, 2008 at 5:27 am
@Nathan Myers: The observed characteristics (lightcurves, spectra etc.) of a GRB match the predictions made by the model of an exploding star. So, why do you call this a “guess”? Do you suggest that stars don’t explode? Or that they explode differently than what our models say? If yes, you essentially say that most of we know about physics is wrong.
@Ryan Jensen: It seems to me that you make the same mistake as lots of people (thanks to the media misrepresenting the Big Bang theory): the Big Bang theory doesn’t say that we all started at the same place and matter traveled outward from there in all directions. A much better analogy is an expanding balloon - were the universe is not the interior, but the *surface* of the balloon (a surface is two-dimensional, while the universe is three-dimensional - but it’s a bit hard to imagine a four-dimensional balloon with a three-dimensional surface in your mind…
). We are (almost) fixed at one point on this surface, while light is free to travel around. So, both we and the light travel (in a sense - don’t take that literally!) outwards from the center of the balloon (this center you can picture as the point where the BB happened - but note that this point is *not* part of the universe, which is only the surface of the balloon!), and the light is at the same time moving on this surface towards us. Does this help in any way? If not, try this:
http://www.astro.ucla.edu/~wright/cosmolog.htm
http://www.talkorigins.org/faqs/astronomy/bigbang.html
@Phil: Saying that the light traveled 12.8 billion light years is a bit misleading, I’d say. According to the “cosmology calculator” of your colleague Ned Wright, redshift 6.7 means that this GRB happened 12.715 billion years ago (the source which says 12.8 billion years probably uses slightly different values for the cosmological parameters), and its source is now 27.468 billion light years away - hence the light traveled around 27.5 billion light years…
http://www.astro.ucla.edu/~wright/CosmoCalc.html
September 20th, 2008 at 5:48 am
Corrections to my last comment:
First, I accidentally typed in a redshift of only 6 instead of 6.7 into the Cosmology Calculator. The right numbers are: the GRB happened 12.842 billion years ago (agreeing now with the stated 12.8 billion light years), and the object which emitted the GRB is now 28.396 billion light years away.
Second, that the object which emitted the GRB is *now* 28.396 billion light years away does *not* mean that the light traveled 28.396 billion light years (as I originally implied). The light traveled 12.8 billion light years, just as Phil said. But at the same time, the object which emitted the GRB was “drawn away” from us (by the cosmic expansion), hence the much greater distance now. Sorry for the mistake - I hope this did not cause even more confusion!
Calculating its distance to us when the light we see now was emitted is fairly easy, BTW: one plus the redshift gives the factor by which the universe has expanded since then. So the universe has expanded by a factor of 7.7, and hence this object was already 28.396 billion light years/7.7 = 3.688 billion light years away from us when the GRB happened!
September 20th, 2008 at 5:59 am
Nathan said: “It’s one thing to imagine a process that might release enough energy, and entirely another to demonstrate that such a process is actually doing it in this case. In a real science, your colleagues would expect the latter.”
In another blog I asked what your training, in science or as a scientist, is.
One of the reasons I asked is that the more I read of your comments, the less it seems you understand of modern science, and in particular astrophysics and cosmology.
So if you don’t mind, let’s consider the Sun … processes by which the Sun produces, and releases, the energy we detect in the form of photons and neutrinos here on Earth, at the rate we detect it, can be found in many textbooks.
In the Nathan Myers view of how science is done, what would constitute “demonstrat[ing] that such process[es are] actually” producing and releasing in the case of the Sun?
More generally, what are the sorts of things that you consider constitute “demonstration” in astrophysics and cosmology?
September 20th, 2008 at 5:59 am
Correction to my last post.
I incorrectly said that although the light had taken 12.8 billion years to reach us, it hadn’t actually travelled 12.8 billion light years. This was, of course, rubbish.
What I was attempting to say was that the distance the light has travelled is not the actual distance between us and the object in question. The distance travelled is significantly less - since space has been expanding whilst the light has been travelling.
September 20th, 2008 at 6:48 am
StevoR said: “Have any gravitational waves from anything ever been detected?
Are gravitational waves known from any solid facts or are they just inferred by orbital dynamics? Not knocking them mind, just unsure if we’ve got anything other than reasonable hypothesis on them.”
If you mean directly detected, then no, not yet.
However, Hulse and Taylor got a Nobel, in 1993, for their work on a binary pulsar, showing that the (mutual) orbit is decaying in a manner consistent with loss of energy due to gravitational radiation. Since then several other binary (and one double) pulsars have been observed, and all results are consistent with the theory of General Relativity and the loss of orbital energy due to such radiation.
September 20th, 2008 at 7:39 am
I’m going dizzy trying to keep up with all the corrections and errata to individual comments.
September 20th, 2008 at 8:26 am
Wish we didn’t have to make them - & could edit our original posts instead, Gkopy.
September 20th, 2008 at 8:41 am
DeiRenDopa answered on Sept. 20th, 2008 at 6:48 am :
“.. SNIP .. If you mean [gravitational waves] directly detected, then no, not yet. However, Hulse and Taylor got a Nobel, in 1993, for their work on a binary pulsar, showing that the (mutual) orbit is decaying in a manner consistent with loss of energy due to gravitational radiation. Since then several other binary (and one double) pulsars have been observed, and all results are consistent with the theory of General Relativity and the loss of orbital energy due to such radiation.”
Thanks for that answer - appreciated!
I gather that one of the things they hope to find with the LHC* is
‘gravitrons’ or the particles responsible for such gravitational waves right? Or maybe the Higgs Boson “god particle” is involved somehow too -mass & gravity? Afraid I’m not great with that esoteric cosmological stuff,
it gets way above me I’m afraid ..
* Yes, I’m a little uneasy about the LHC and some of the issues with it. I
think & hope the scientists involved know what they’re doing. I wish they were a bit more careful and a bit more considerate of those who do feel uneasy whether for good reasons or not. This atom-smashing stuff always reminds me of splitting the big atom and some of the nasty consequences of that - Hiroshima, Nagasaki and Chernobyl to name just three. I don’t expect that the LHC’ll destroy the world, I just get this gnawing sense of anxiety over it anyway … I wish they’d do some more checking and ethical reviews and preferably move it off-planet. Off-Topic I know &reallydon’t want to
hijack the thread but just thought it needed saying.
September 20th, 2008 at 8:46 am
Oh & if can ask again :
Is it recomended practice /good netiquette /theright thing here to put peoples “names” in bold text - esp.if ypir’e responding to them?
Anyone, please?
——–
“Night hides the world but reveals the universe!”
- Russian proverb.
September 20th, 2008 at 8:50 am
12.8 billion years eh?
I guess in .001 billion years (all math is approximate) we’ll receive our first alien radio transmission coming from the same area. I predict it’ll be something along the lines of “SHIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII-” then static.
September 20th, 2008 at 9:00 am
@StevoR:
AFAIK, the LHC won’t tell us anything about gravitons. There might be a tiny possibility that it could tell us something about additional dimensions (like those proposed in string theory), and that could then perhaps shed some light on gravity - but that’s all I can think of.
The Higgs is indirectly involved with gravity. The important thing for gravity is not mass, but energy (even photons experience and even exert gravity, although they have no (rest) mass). By interacting with the Higgs, particles “gain” mass - without the Higgs, particles would not have a (rest) mass. But according to Einstein, as soon as you have mass, you have energy (E = mc^2, you know…
). Hence due to the Higgs, even particles at rest have energy (so-called “rest energy”); without the Higgs, particles would only have (kinetic) energy when they move. So due to the Higgs, there is more energy and hence more gravity than there would be without it. Was this comprehensible in any way? 
What makes you think the scientists at the LHC are *not* careful enough? After all, they *have* considered the opinions of the “dissenting” scientists - and have found there arguments wanting. And what makes you think there is not enough “checking”? What exactly do you expect them to do?
And do you also suggest ethical reviews when people build new planes and cars? AFAIK, the risk of dying in a car accident or plane crash is far higher than the risk of being eaten by a Black Hole created by the LHC…
Comparing this to nuclear bombs or Chernobyl is just silly, sorry. There energies involved in those latter cases was by *many* orders of magnitude greater than the energies which are achieved at the LHC. And as you said: atomic bombs etc. were *consequences* of “splitting the atom” (actually, splitting the atomic nucleus, BTW
). Splitting the nucleus in itself did *not* directly result in these catastrophes - it only paved the way for them. So you could perhaps argue that the things discovered at the LHC could perhaps someday be used to make bigger bombs or something like that - but arguing that the LHC in itself is dangerous does not follow.
September 20th, 2008 at 9:48 am
Reputable End of the World Scenarios
A new book is in press, and will be released in a month. The author of the BadAstronomy blog, Phil Plait has written “Death From the Skies: These Are the Ways the World Will End!” That’s him, exhibiting typical Ivory Tower Professoria…
September 20th, 2008 at 11:24 am
Ok, so please forgive the uneducated me, but I always was under the impression that stars live for at least close to a billion years. Now there is a massive star that lived for only 400 million years? Phil or anyone here who is more informed than I am please care to explain?
So we have a massive star (hence the massive gamma ray burst) that was among the first stars in the universe, which means that it consisted of mostly hydrogen atoms. So a lot of hydrogen to make a massive star. One should assume that such a star would burn longer, since it had a lot of fuel to burn. 400 million years seems very short to me, even for a small star. Only explanation that I could think of is that that it burned out faster due to more fusion reactions happening thanks to its higher mass, but that seems a little far fetched.
So Phil can you maybe devote a few sentences for us interested yet uneducated fellows to explain how this thing came about? It is definitely the most unexpected thing I have read in regards to astronomy lately…
September 20th, 2008 at 11:33 am
@Elmar_M: What you think of isn’t “far fetched” at all - the more massive a star, the faster it “burns” the hydrogen, and the shorter its life. And no, stars don’t have to live for “at least close to a billion years”. Very massive stars last only some million years. And we don’t need Phil to explain that - simply go to Wikipedia and look at the article on stellar evolution.
September 20th, 2008 at 11:56 am
Elmar M:
The more massive the star, the stronger its gravity. The stronger its gravity the denser the core. The denser the core, the higher its temperature. The higher its temperature, the faster the rate of fusion. The increase in fusion rate far outstrips the relative increase in size. Thus more massive stars burn hotter (note their color), deplete their fuel faster, and live shorter.
I’m not the first to make a comparison to James Dean. Life fast. Die young.
September 20th, 2008 at 12:41 pm
@DRD: “More generally, what are the sorts of things that you consider constitute ‘demonstration’ in astrophysics and cosmology?” Cosmology, as much fun as it may be for participants, offers few opportunities to demonstrate anything positive. Astrophysics offers more, principally in connection with nearby, non-point-source, events. (The sun, since you mention it, is not a point source, yet much remains unknown about it.) The alternative to being honest about the limits on astronomical understanding is to pretend, which seems to be Phil’s choice, supposed skepticism notwithstanding.
It must have got tedious to say “we can but guess” at astro/cosmo-this’n'that conferences, so it’s easy to see why they would dispense with it there. That doesn’t excuse the behavior in public, where pronouncements from many different scientific disciplines are presented, many of them conducted with rather more rigor. Would you excuse this on the basis that astronomical facts and fallacies have equal — nil — consequences, so they might just as well all be presented with absolute confidence?
@Bjoern: “The observed characteristics (lightcurves, spectra etc.) of a GRB match the predictions made by the model of an exploding star. So, why do you call this a “guess”? Do you suggest that stars don’t explode? No. Matching lightcurves are suggestive. We might never know, with the sort of confidence we have about laboratory phenomena, what is really involved in these events. To pretend to know what you don’t know is religion, or (in Phil’s terminology) “woo”.
September 20th, 2008 at 1:00 pm
Finally I understand where Nathan is coming from. Nathan thinks anything that we can’t poke with a stick is pure supposition, guess work, religion or woo. Nothing can be surmised, derived, hypothesised or scientifically proven because we can’t stick it in a test tube. All astrophysics is bunk until proven, to Nathan’s satisfaction, otherwise. Alternative theories have as much validity as the scientific consensus because he says so.
Having said that I am thoroughly enjoying the exchange between Nathan and DeiRenDopa on other threads.
September 20th, 2008 at 2:52 pm
@shane
Nathan thinks anything that we can’t poke with a stick is pure supposition, guess work, religion or woo
Not, quite. If we can poke something with a stick, he’ll just make some vague statement about how true scientists and skeptics admit we don’t really understand the true nature of sticks.
September 20th, 2008 at 4:02 pm
Space expansion via DARK ENREGY, or spacial stretching Via A really big black hole(ie, Great Attractor)/
Any comments???
GAry 7
September 20th, 2008 at 4:29 pm
@shane: You can’t poke electrons with a stick, or DNA bases, or phonons in crystals, and we’ve never seen a pterosaur fly. We do, however, have many different lines of evidence confirming each.
September 20th, 2008 at 5:08 pm
in the words of 3-D homer “HOLY GUACAMOLY”
September 20th, 2008 at 6:09 pm
[…] Posted by slang BA’s story on this. Some of the comments there… BA ToSeek’ed by DA! __________________ David […]
September 20th, 2008 at 6:24 pm
Thanks for the explanation everyone. I learned something today (or relearned). Yeah the higher fusion rate due to the higher forces in the core was my suspicion,but I was not sure that it would really outweight the amount of fuel that signifficantly.
Anyway I was never aware of how shortlived some stars can be, so thanks for explaining that.
September 20th, 2008 at 7:22 pm
@Nathan: first, thanks for answering my question.
By now I guess you won’t be at all surprised to read that your answer only makes more confused, not less.
For starters, you didn’t actually say anything about what, in your view, constitutes “demonstration”, in astrophysics or cosmology!
As I read your comment, readers must cudgel their brains to tease meaning out of your cryptic words …
“Cosmology […] offers few opportunities to demonstrate anything positive” - so what are those few??
“Astrophysics offers more, principally in connection with nearby, non-point-source, events.” - so how many more? and what is the relationship between “nearby, non-point-source, events” and demonstration?? and what sorts of not nearby, point source, non-events (?) in astrophysics offer “opportunities to demonstrate [some]thing positive”, albeit few in number???
But perhaps the most confusing part of your comment (that I am quoting) is this: “Matching lightcurves are suggestive. We might never know, with the sort of confidence we have about laboratory phenomena, what is really involved in these events. To pretend to know what you don’t know is religion, or (in Phil’s terminology) “woo”.”
May I ask, Nathan, if you are familiar with the Copernican principle? In particular the version of it about the laws of physics being the same everywhere in the universe (or something like that)?
If not, please say so and I’ll provide some reference material; if so, may I ask to what extent your view of astronomy and cosmology, as sciences, contains at least a weakening of that principle, if not an all-but-complete rejection of at least some version of it?
September 20th, 2008 at 7:32 pm
ToSeek’ed, ToSeek’ed, hehe. As Slang said, you should check into BAUTforum every once in a while.
But I am miffed at something. One might say the Bad astronomer is commiting Bad astronomy. Swift first localized this event in gamma rays. This rough position then allowed the ESO 2.2m telescope at La Silla observatory, Chile, to not only discover the optical/NIR afterglow (completely invisible to Swift UVOT), but also to determine the redshift in a rough photometric fashion. It was this first rough result which triggered the “monster 8-m telescope” (for those interested in technical details, the ESO VLT), specifically an observing proposal geared to observe GRBs at very high redshifts.
While swift lay at the beginning of this chain, the true discoveries came from ESO telescopes.
As I mentioned to an American colleague of mine, this is a European burst!!
September 21st, 2008 at 12:53 am
@Bjoern:
So are we then looking back in time along this expanding surface, and not to the central event itself. I can’t quite picture how that would look in my mind. I always thought we were, in a sense looking back in time to that starting point of the BB?
September 21st, 2008 at 12:55 am
I should make it more clear when I say looking back along this expanding surface. I meant to say are we not looking into the central event? I guess the analogy would be looking beneath the surface of the expanding balloon to see what is inside it?
September 21st, 2008 at 1:01 am
@DRD: I confess I am at a loss to guess how you come to a weakening of the great Copernican Principle from my plain words. I am most entranced, however, by your offer to conjure, for me, a gamma-ray burst in your cunningly artificed laboratory (directed away from any persons, I do hope). In the meantime, to your questions, I apply myself diligently.
Sadly, cudgel my brains how I would, I cannot at this moment offer you any examples of the “few” you ask; for all I wot there may be none at all, which would be “few” enough indeed! Of the “more”, I hasten to offer in evidence, but with no claim to exhaustiveness, the elucidation of the orbits of the planets, and the precise delivery of space probes to them on time and on target (notwithstanding unaccounted oddities in the Pioneers’ trajectories).
I will end with a quote from Richard Feynman: “I know how hard it is to get to really know something; how careful you have to be about checking the experiments; how easy it is to make mistakes and fool yourself. I know what it means to know something.” Astronomers may disagree with him, but I’ll side with Dick: an honest astronomer might announce that he or she suspects that a GRB may come out of a collapsing first-generation star, but not claim to know so.
September 21st, 2008 at 1:51 am
@Nathan You can’t poke electrons with a stick, or DNA bases, or phonons in crystals, and we’ve never seen a pterosaur fly. We do, however, have many different lines of evidence confirming each.
You almost got it Nathan. Replace your first line with “Cosmology and astrophysics” and then add your second line… We do, however, have many different lines of evidence confirming each.
September 21st, 2008 at 2:11 am
@Michael L:
Let’s try this in again one dimension less. Picture an expanding circle in your mind. The circle line is the universe, the middle point is the point where the Big Bang happened.
Now, when you “look back”, you neither look along the circle line nor at the middle point directly. Your “line of sight” is like a spiral, going inwards to the middle point (but a spiral with actually less than even one winding!).
September 21st, 2008 at 2:18 am
@StevoR:
Sean Carroll at the Cosmic Variance blog wrote a nice article titled “Talking About LHC Safety”:
http://cosmicvariance.com/2008/09/20/talking-about-lhc-safety/
September 21st, 2008 at 5:01 am
Nathan Myers: How stringent is your criteria for your definition of “know”?
I think it is fair for me to say that I know that the available evidence concerning long GRB’s is more consistent with the model of an exploding giant star than any other model so far proposed.
But all scientific knowledge can be expressed in these terms, and no such knowledge is absolutely certain. But it strains towards the ridiculous to say that one can’t say one “knows” that gravity is an attractive force, or that one “knows” that the sun will appear to rise in an eastward direction tomorrow, as these are likewise statements and predictions related to scientific models not confirmed with absolute certainty.
Are you saying then that somehow the evidence suggesting long GRB’s are due to exploding stars is particularly inadequate of insufficient, such that one can’t be justified in using the term “know”, as compared to other items of scientific knowledge? If so, what are the flaws in this evidence that you think so egregious?
To me it seems that the evidence favoring long GRB’s being due to exploding giant stars is at least as good as the line evidence that suggests that pterosaurs could fly. I personally would not hesitate to say that I “know” both these things. It is taken as a given that there is a certain provisional quality to the term “know” when used in these contexts.
September 21st, 2008 at 8:07 am
continuing to look at Nathan’s view of the nature of modern astrophysics and cosmology, and now (it seems) science in general …
Nathan, would you be kind enough to explain, as clearly as you can, what you see as the key criteria for assessing “evidence”, in astrophysics, and the extent to which there are distinct classes of certainty wrt conclusions?
For example, the distance to an eclipsing binary, the mass of the plasma component of the inter-galactic medium of a nearby rich cluster of galaxies, the energy spectrum of ultra-high energy cosmic rays.
September 21st, 2008 at 11:22 am
I’m back…. again, after a year off. And I have almost all those comments to catch-up on. Hi Phil.
I’m halfway thru this forum, but couldn’t resist commenting. Apologies to anybody in the second half who may have similar comments.
@ Jay, (Sept. 20, 2008 at 04:56 am and
@Bjoern, (Sept. 20, 2008 at 05:27 am, and others before then,
there are questions and answers re the light seemingly catching-up with us just now, after 12.8 0dd bn lys.
Space has, to us at least, three basic dimensions, and Light considered the fourth, and maybe a dozen others that I have no personal evidence of.
We live in a world where things are to the right, left up or down etc., but we cannot imagine any light coming to us other than a direction that all other light has also in the past. A little thought would indicate that light from that “balloon” of a Universe, even if it is expanding, will….must….. come in from different directions. So even if we are on that “surface”, most events will NOT arrive at the same time for us to catalog them. (Except that one first Big Bang, which was a point source at a particular time - namely Zero!)
Anything that happened after 800Mlys would, and, could be actually closer, but at a different angle and direction, forming a simple triangle with the original Time Zero, and us observing a long way away, because we are moving in another direction, maybe on the other side of the Universe. Seems like simple geometry to me, but then….
Anybody want to expand, correct, or comment? Or am I pushing the simplistic model a bit too far?
Ivan. (Now back to reading the second stanza of comments.)
September 21st, 2008 at 12:08 pm
@icemith: You are indeed pushing the model too far. The flaw is in thinking that the direction into which the balloon expands (radial direction) is a real spatial direction. In reality, that direction (dimension) doesn’t really exist (in General Relativity, space can be curved without there being a large space it curves into… don’t try to picture that in your mind!
). At best one could say that it represents the temporal direction.
September 21st, 2008 at 1:00 pm
A comment on the “poking with a stick” theme brought up by Nathan Myers and other. If I see, with my own eyes, X happen 10 feet away, does that mean that I cannot say that X happened because I did not touch X to confirm that it was real?
Because in astronomy and cosmology, that is exactly what we do. We are seeing, with our eyes and instruments, the actual photons generated by the events in question. In a very real sense, we may not have reached out and poked it with OUR stick, but it has reached down and poked us with ITS stick.
September 21st, 2008 at 1:06 pm
Further to knowing, demonstrating, and evidence and what Nathan’s criteria for them in astrophysics, I found something Nathan said earlier, in another blog, of possibly very considerable pertinence: “It’s a simple fact that all the detectable mass in the universe, save planet(oid)s, is plasma, partially or fully ionized, high-density or low. It’s a simple fact that the mass of low-density plasma far, far out-masses all the mass in stars and planets.”
In another comment, Nathan seems to provide at least one source for how he knows these “simple facts”: “You might even find there [in the Encyclopedia Britannica] an uncontroversial estimate for how much of the (hadronic, observable) universe is made of it.”
Now I don’t know which part(s) of the EB Nathan used as his source(s), so I can’t be sure, but it seems likely the authors of those EB materials used the standard tools and techniques of modern astrophysics, directly or indirectly.
I wonder how many of the same (astrophysics) tools and techniques were used to arrive at the “simple facts” above as the various aspects of GRBs that Nathan so vehemently and categorically attacks Phil for stating?
September 21st, 2008 at 2:35 pm
Nathan said: “I hasten to offer in evidence, but with no claim to exhaustiveness, the elucidation of the orbits of the planets” … this in response to request for something concrete concerning what he considers acceptable “demonstration” in astrophysics.
Am I alone in finding it ironic that the first such concrete kind of demonstration concerns gravity and not plasmas? Further, it’s gravity in association with the only (trivial?) exception to plasma (”It’s a simple fact that all the detectable mass in the universe, save planet(oid)s, is plasma”)!
I also find it curious that Nathan chose this particular class of “demonstration”, because
a) in another blog he commented “Any time an observed phenomenon cannot be accounted for by the gravitation of observable matter, dark matter is trotted out and simply assumed to have been placed wherever needed to produce the observed effect by adding in its gravitation”
b) the same technique has been used to estimate the mass of SgrA*, from observations which elucidated the orbits of several stars around it.
So maybe it’s doubly ironic that we “know” SgrA* is a SMBH (supermassive black hole), not “dark matter” to be sure, but given Nathan’s stated scepticism re neutron stars, it would be quite curious if he were not at least as sceptical about black holes.
September 21st, 2008 at 4:02 pm
Thanks Bjoern,
I can sort of picture that.
September 21st, 2008 at 5:35 pm
It is absolutely amazing to see such an event at such a distance knowing it must have happened in such a distant past. It also raises many questions. That Dr. Plait mentioned looking at such an event is like looking into a mirror makes me wonder roughly how far away would an exploding star have to be from our corner of the universe to have actually created us? The matter ejected from such an event would necessarily travel at less than the speed of light and the GRB would travel at the speed of light right? Thus we would not be able to see our own creation since the light from the exploding star or stars that created us would have passed us before the matter which is us. I don’t know about the rest of you, but that thought makes my brain ache, but in a good way. Any further comment on that Dr. Plait? I’m curious about how astronomers think about time and distance when looking into the night sky. Each point of light or event must represent a different time years to billions of years apart from one another. How does this affect efforts to map the universe? Wouldn’t it be something like refraction of light in water where things are not where they appear since by the time you see them they may no longer exist? Something close like alpha centauri still exists each time we observe it but something distant like this? Wondrous.
September 21st, 2008 at 11:27 pm
Bjoern said on Sept 21st, 2008 at 2:18 am :
“@StevoR: Sean Carroll at the Cosmic Variance blog wrote a nice article titled “Talking About LHC Safety”:
http://cosmicvariance.com/2008/09/20/talking-about-lhc-safety/ ”
Thanks - read that & also went via that site to the LHC -CERN site itself. Interesting. I feel a bit better about it but I’m still not 100% convinced ..
There is still always the unforeseen - both with the results of the experiment and with its ultimate implications as with atomic nucleus splitting -> A & H bombs -> Cold war threat of Nuclear Armageddon, current threat of terrorists getting hold of Nukes - or mad leaders of superpowers etc ..
The prospects of anything catastrophic happening may be 0.0000000000001% the prospects if we choose NOT to turn it on are far lower still! As for the toxic pasta sauce analogy - Bleeech! I’m not impressed. We’re NOT talking about opening cans of pasta or bacteria which we understand pretty well - we’re talking about tampering with particles that we don’t even know exist - a different kettle of fish entirely.
I think all will go well, I hope & expect so .. all the same - I’d rather we had the same sort of moratorium on particle accelerators and colliders that we do on human cloning. Observational astronomy and cosmology -fanatstic, artifical human messing about with same not so much …
I did actually e-mail their contact us site with my single allotted question being :
“Has the LHC experiment had any ethical review by trained ethicists - if so what were the results, if not then why not?”
Hopefully I’ll get an answer soon - although they did note
“.. that it can take several days before your question is answered.”
Thankfully now there’s been the delay they have some extra time to think again and conduct one if they haven’t already.
September 22nd, 2008 at 12:15 am
Bjoern said : September 20th, 2008 at 9:00 am
“@StevoR:
AFAIK, the LHC won’t tell us anything about gravitons. There might be a tiny possibility that it could tell us something about additional dimensions (like those proposed in string theory), and that could then perhaps shed some light on gravity - but that’s all I can think of.
The Higgs is indirectly involved with gravity. The important thing for gravity is not mass, but energy (even photons experience and even exert gravity, although they have no (rest) mass). By interacting with the Higgs, particles “gain” mass - without the Higgs, particles would not have a (rest) mass. But according to Einstein, as soon as you have mass, you have energy (E = mc^2, you know… ). Hence due to the Higgs, even particles at rest have energy (so-called “rest energy”); without the Higgs, particles would only have (kinetic) energy when they move. So due to the Higgs, there is more energy and hence more gravity than there would be without it. Was this comprehensible in any way?
Umm .. slightly. Thanks!
“What makes you think the scientists at the LHC are *not* careful enough? After all, they *have* considered the opinions of the “dissenting” scientists - and have found there arguments wanting.
I don’t fully trust them - or any particle or nuclear physicists. Simple as that really.
Why not you ask? Well these are the same people who put our entire planet under the shadow of the Bomb. That told us nuclear energy was fine & dandy and never mind the radioactive wastes. They told us Chernobyl was safe. Sorry Dr Brien Cox and others but after that little list of threats your area has created to our very existence, its going to be very hard to take your reassurances on anything with less than a big pinch of salt.
“And what makes you think there is not enough “checking”? What exactly do you expect them to do?”
I’d like - although I don’t expect - for them to stop experimenting with these particle colliders and find alternatives that use natural cosmic rays as detectors instead. I’m all for observational science, I’m not so keen on the experimentational variety. Not when it comes to the nuclear particle physics area anyhow.
“And do you also suggest ethical reviews when people build new planes and cars? AFAIK, the risk of dying in a car accident or plane crash is far higher than the risk of being eaten by a Black Hole created by the LHC…
No but they are self-evidnetlyvery different cases with consequences that are vastly different. Okay, your car or plane can sometimes crash killing afew people - the LHC could potentially - a very, very remote chance sure but what folks are worried about - destroy our entire planet.
“Comparing this to nuclear bombs or Chernobyl is just silly, sorry. There energies involved in those latter cases was by *many* orders of magnitude greater than the energies which are achieved at the LHC. And as you said: atomic bombs etc. were *consequences* of “splitting the atom” (actually, splitting the atomic nucleus, BTW ). Splitting the nucleus in itself did *not* directly result in these catastrophes - it only paved the way for them. So you could perhaps argue that the things discovered at the LHC could perhaps someday be used to make bigger bombs or something like that - but arguing that the LHC in itself is dangerous does not follow.
I think that that bit I have put in bold from your quote there is something we should consider, yes.
As for it being “silly” to compare the results of nuclear phyisics with the results of sub-nuclear partcile physics - well I don’t think I’m stretching too long a bow there, I really don’t. We’ll just have to agree to disagree on that.
I love astronomy and I’m usually all in favour of science but the LHC is an exception to that general rule - along with using sceince to build bigger and worse nuclear bombs & other WMDs. Science is a double-edged sword and I think we do need to use care in how we weild that sword.
September 22nd, 2008 at 1:09 am
@StevoR I don’t fully trust them - or any particle or nuclear physicists. Simple as that really.
Why trust anybody? Pure research ain’t going to hurt anybody. It is the application of that research that can be misused. In that case blame the engineers (being facetious here - I’m not really suggesting blaming anybody). Add up all the deaths, cancers and mild sickness caused by the nuclear industry including Chernobyl, Nagasaki and Hiroshima and the number will be a small fraction of all the casualties caused by the internal combustion engine. You will never have a scifi story about someone going back in time to waste Herr Benz to prevent the carnage the automobile will cause. I suppose we should probably also halt fusion research because, you know, we could make a binary companion for our star.
BTW, I don’t think anybody ever suggested Chernobyl was safe - not in the west.
September 22nd, 2008 at 7:47 am
@StevoR:
“No but they are self-evidnetlyvery different cases with consequences that are vastly different. Okay, your car or plane can sometimes crash killing afew people - the LHC could potentially - a very, very remote chance sure but what folks are worried about - destroy our entire planet.”
I provided you a link to the Cosmic Variance blog. Did you read the analogy with the jar of tomato sauce there?
September 22nd, 2008 at 8:44 am
@amphiox: “Poking with a stick” was “shane’s” cheap conceit. If you have questions about it, you may ask him directly.
@DRD: Your pose is slipping. I suppose it had to, eventually, when you find yourself defending a former scientist turned internet clown who calls anyone he disagrees with an “antiscientist”. (It makes me wonder about poor Mr. Randi.) Please let me know when you have any technical questions.
September 22nd, 2008 at 10:29 am
@Nathan Myers
Might I make a suggestion for your future comments criticizing Dr. Plait’s posts:
1) Provide a clear argument of where he is incorrect.
2) Provide evidence to support that argument.
3) Provide links to that evidence.
4) Leave the ad hominems at home.
I lost track of the thread I asked this in, but I’m still curious: what exactly is your beef with Phil? Even where you are not making any specific criticism of the science behind his posts, you come out all snarky and derisive about anything, even grammar. So, what’s up? If you don’t like his stuff, then don’t read it.
September 22nd, 2008 at 10:46 am
@Nathan: I have no idea what you’re talking about!
I am neither “defending” nor attacking Phil, nor anyone else!!
May I ask how you came to that conclusion?
As for questions, I note that there are quite a few, nearly all technical, that I have asked you (respectfully, I hope) that you have not yet answered.
Here is the last direct questions, in this blog:
>”Nathan, would you be kind enough to explain, as clearly as you can, what you see as the key criteria for assessing “evidence”, in astrophysics, and the extent to which there are distinct classes of certainty wrt conclusions?
For example, the distance to an eclipsing binary, the mass of the plasma component of the inter-galactic medium of a nearby rich cluster of galaxies, the energy spectrum of ultra-high energy cosmic rays.”<
In my next comment I’ll rephrase some of the content of some other, recent, comments of mine into the form of direct, technical questions concerning what you have written here.
September 22nd, 2008 at 11:00 am
If 13.6 billion years ago there was “singularity” and .8 billion years after the “big bang” a GRB occurs, where were we (or at least the matter we are comprised of) at that time, in relation to the GRB? It would seem that the light from the GRB would have long ago shined past us. Isn’t the universe larger now then it was then? How fast is it expanding? Its not anywhere near the speed of light, is it? Can these questions be answered or can’t I understand the answer?
September 22nd, 2008 at 11:12 am
Nathan said: “It’s a simple fact that all the detectable mass in the universe, save planet(oid)s, is plasma, partially or fully ionized, high-density or low. It’s a simple fact that the mass of low-density plasma far, far out-masses all the mass in stars and planets.”
@Nathan: how were these “simple facts” established, to your satisfaction?
Specifically, what tools and techniques of astronomy or astrophysics were used to “demonstrate” them?
Also, given that you cannot think of anything that offers the opportunity to demonstrate anything positive in cosmology, may I ask how you would go about attempting to explain the following?
* why the night sky is dark (Olbers’ paradox)
* why nothing seems to be older than ~10 billion years
* why the CMB has a SED (spectral energy distribution) that is a ~3K blackbody (to within 1 part in ~1000) overlaid by a dipole
* why estimated distance correlates so well with redshift, for all objects beyond a few Mpc
* why there seems to be so little mass in the form of elements Li to U, compared with mass in the form of H and He.
September 22nd, 2008 at 12:58 pm
@Nathan: here’s another question I asked you earlier, which you have not yet answered (or, if you did, I missed it; apologies - would you mind repeating your answer?)
“So if you don’t mind, let’s consider the Sun … processes by which the Sun produces, and releases, the energy we detect in the form of photons and neutrinos here on Earth, at the rate we detect it, can be found in many textbooks.
In the Nathan Myers view of how science is done, what would constitute “demonstrat[ing] that such process[es are] actually” producing and releasing in the case of the Sun?”
I’d appreciate reading your answer to this question.
September 22nd, 2008 at 1:01 pm
@shane: do you mind if I ask what it is about the exchanges between DRD and Nathan Myers on other threads that you find most insightful?
And is there anything in what DRD wrote that you think could have been better expressed?
September 22nd, 2008 at 1:16 pm
Nathan said: “@DRD: Do you pretend to know what exactly produces these gamma-ray bursts, and how they go about doing it? It’s one thing to imagine a process that might release enough energy, and entirely another to demonstrate that such a process is actually doing it in this case. In a real science, your colleagues would expect the latter.”
What I, DRD, personally think, or am prepared to say I know (whether “exactly” or not) is surely pretty irrelevant, isn’t it? (rhetorical)
Surely the pertinent question, regarding the nature of long GRBs, is how the scientists who study them have come to conclude that they originate as certain kinds of supernovae (within the usual bounds of uncertainty associated with all such research)?
My thanks to Don Alexander, whose recent post in the BAUT Forum lead me to this 2006 paper:
The Supernova Gamma-Ray Burst Connection, by S.E. Woosley and J.S. Bloom. Here’s the abstract:
“Observations show that at least some gamma-ray bursts (GRBs) happen simultaneously with core-collapse supernovae (SNe), thus linking by a common thread nature’s two grandest explosions. We review here the growing evidence for and theoretical implications of this association, and conclude that most long-duration soft-spectrum GRBs are accompanied by massive stellar explosions (GRB-SNe). The kinetic energy and luminosity of well-studied GRB-SNe appear to be greater than those of ordinary SNe, but evidence exists, even in a limited sample, for considerable diversity. The existing sample also suggests that most of the energy in the explosion is contained in nonrelativistic ejecta (producing the supernova) rather than in the relativistic jets responsible for making the burst and its afterglow. Neither all SNe, nor even all SNe of Type Ibc produce GRBs. The degree of differential rotation in the collapsing iron core of massive stars when they die may be what makes the difference.”
Here is its entry in ADS (note that it has already been cited 151 times (caveats apply), so it seems to be pretty well regarded by other astrophysicists): http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:astro-ph/0609142
Perhaps, if you can see flaws in this work, you could write a paper describing those flaws and submit it to ApJ or MNRAS?
September 22nd, 2008 at 2:31 pm
@Nathan: I’m a bit slow today …
This is what you wrote: “[Phil] calls anyone he disagrees with an “antiscientist”.” Yes, truly you did!
Now either you’re getting way too carried away, or you didn’t mean it.
Why?
Because in this very page Don Alexander disagreed with Phil, quite directly and openly (”One might say the Bad astronomer is commiting Bad astronomy”).
Did Phil call Don Alexander an “antiscientist”? I don’t think so. Of course, DA disagreeing with the BA is not the same as the BA disagreeing with DA, but I’m pretty sure any reader could find examples of Phil disagreeing with someone without calling them an antiscientist; in fact, in my reading of the Discovery blogs, the only person I can recall Phil calling an antiscientist is you (but perhaps my memory is not entirely accurate …).
September 22nd, 2008 at 10:01 pm
DeiRenDopa, I’ve found your exchanges with Nathan to be polite, informative, clear and coherent. So far you haven’t fallen into the trap of snarkiness that some of us (myself included) fall into when faced with obtuseness.
September 22nd, 2008 at 10:38 pm
I did refer to Nathan as antiscienists, and that was after several direct questions that all he answered back with were insults.
September 23rd, 2008 at 8:19 am
The key here isn’t “far, far away”, it’s “long, long ago”. That’s more reassuring
September 23rd, 2008 at 8:31 am
@Weird stuff:
“If 13.6 billion years ago there was “singularity” and .8 billion years after the “big bang” a GRB occurs, where were we (or at least the matter we are comprised of) at that time, in relation to the GRB?”
As I already outlined earlier (September 20th, 2008 at 5:48 am), we were at a distance of about 3.7 billion light years to the star when the GRB happened.
“It would seem that the light from the GRB would have long ago shined past us.”
I don’t see how you arrive at that conclusion, sorry.
“Isn’t the universe larger now then it was then?”
Yes, it is larger by a factor of about 7.7, see the comment mentioned above.
“How fast is it expanding?”
About 7% every billion years; in the past, that rate was higher, in the future, it won’t change much (if the expansion is dominated by Dark Energy).
“Its not anywhere near the speed of light, is it?”
It makes little sense to compare the expansion “speed” of the universe with light speed. In order to say that the universe increases x kilometers per billion years, you’d first have to know its momentary size. But we don’t don’t that size - it could even be infinitely large! Hence the only thing we can say is by how many % it increases per billion years.
“Can these questions be answered or can’t I understand the answer?”
I hope you understood my answer.
September 23rd, 2008 at 12:23 pm
@Bjoern, Thank You. I really appreciate your comments. Sorry for not reading the entire thread before posting.
If I may clarify one thought, however, it would be the following.
” It makes little sense to compare the expansion “speed” of the universe with light speed.”
I guess what I was thinking was that if part of our galaxy’s movement through space is attributable to universe expansion, then can that portion of movement be expressed in terms of “speed”? If so, then what is that speed? Then if we knew that rate of speed and made an assumption that we and the GRB are moving in the exact oppisite direction then how long would it take for something traveling at or near the speed of light to reach us?
As for this comment “It would seem that the light from the GRB would have long ago shined past us.”
I just made that up. Mostly to give perspective to my inquiries.
Thanks again.
September 23rd, 2008 at 1:00 pm
@weird stuff:
“I guess what I was thinking was that if part of our galaxy’s movement through space is attributable to universe expansion,…”
But that’s not true. *No* part of our galaxy’s movement through space is attributable to universe expansion. Space expands and carries all galaxies, including our own, along with it. The usual analogy here is that space corresponds to an expanding balloon, and the galaxies to coins glued to the surface of that balloon. The coins stay in place, they don’t move across the surface of the balloon. If one coins looks at another, it seems as if the other coin is moving away - but that’s not due to the coin moving on its own, but simply due to the part of the balloon between the coins stretching.
(Well, in reality, galaxies *do* move around - but none of that movement is due to the expansion of the universe.)
September 23rd, 2008 at 1:15 pm
Re Nathan’s comments on astronomy.
While it is, clearly, too early to yet form a definitive picture of ‘where Nathan is coming from’, wrt astronomy, I see the following common aspects:
* with the exception of ‘within our solar system’, it seems that the only consistent stance Nathan can take is that astronomy (and astrophysics and cosmology) is not within the scope of science
* one basis for this stance seems to be a demand that all phenomena (’reality’, if you will) be demonstrable in a lab setting, preferably a lab on (or near) the surface of the Earth, with in situ space probes a possible acceptable secondary setting; active testing (as ‘demonstration’) is also preferred, within lab settings, to passive observation
* alternatively, or perhaps just overlapping this, extrapolations to physical regimes not yet examined in labs are at best highly suspect and at worst completely verboten
* however there are, it seems, different classes of extrapolation; for example, classical electromagnetism can be extrapolated far beyond the range of regimes tested in labs, but gravitation, especially General Relativity, cannot
* the EB and press releases may be regarded as primary sources, wrt scientific veracity and authority.
For those interested in exploring this worldview further, I invite you to read my (or DRD’s, if you have a particularly conservative view re “know”) posts in the JREF Forum’s Science, Mathematics, Medicine and Technology section. One thread I started has already been reference in these blogs (on the observational evidence of cold dark matter), as has another to which I posted heavily (on whether Plasma Cosmology is woo or not - I did not start that thread); there is also a long thread on Halton Arp’s ‘intrinsic redshift’ claims, at least for quasars.
Nathan: I welcome your comments on my tentative summary above, and I would be particularly pleased to read clear expositions of your worldview wrt the extent to which astronomy (astrophysics, cosmology), beyond the solar system, is science.
September 23rd, 2008 at 1:21 pm
Added for clarity: the worldview explored in the JREF Forum posts is that which I have summarised in the first four bullets. I do not know if it’s Nathan’s worldview or not. It is not my (or DRD’s) worldview. A great many of my posts in the JREF Forum are about the consistency of this worldview (or lack of it), in terms of both its internal logic and with good, independently verified, objective experimental results and observations.
September 23rd, 2008 at 3:12 pm
@DeiRenDopa
For God’s sake, call him a name already! It will make you feel better. I fear for your health if you don’t.
September 23rd, 2008 at 6:10 pm
@Jose: please read what shane wrote; I have no intention whatsoever of calling Nathan any name; however, the ideas he presents should stand on their own feet (so to speak).
Further, as this part of the internet is subtitled “Science, Technology, and The Future”, the worldview within which we should judge those ideas is that of modern science … or so I reckon.
September 23rd, 2008 at 9:38 pm
@DeiRenDopa
I know. I’m just starting to think you’re some kind of superhuman. Or maybe a robot. Do you eat old peoples medicine for food?
September 24th, 2008 at 5:21 am
DRD: There’s no need to concoct anything exotic.
* When Todd W demanded documentary support for commonplace facts, I offered the Encyclopedia Britannica as a source he would be likely to trust. I don’t imagine anything “primary” about it.
* Electromagnetics needs to work familiarly (at least under most circumstances) out to remotest reaches for light to behave familiarly there and to get here.
* All phenomena are “within the scope of science”, to the degree they can be observed. However, not all phenomena cooperate to make investigation easy, and not everyone observing them behaves with the discipline rigorous science demands. (Historically, failures within entire branches of science, lasting decades, are legion.) Laboratory phenomena allow more rigorous examination because they can be repeated and studied in many different ways. It’s nobody’s fault that some phenomena are harder to study, and admit less confidence in one’s results, but that doesn’t alter the fact. Solid-state physicists still can’t model high-temperature superconduction, but they don’t pretend.
* Explanation of galactic-scale motion by assuming that only gravitation can possibly be at work has well-known problems; working around these problems (via variant gravity or “dark matter”) seems to be central to much of current astronomical study.
All five of your conclusions are fundamentally faulty.
Do you feel that because cosmological and astronomical results have no domestic consequences, unlike e.g. metallurgy, meteorology, and medicine, standards of evidence ought be relaxed relative to those fields? How much exposure do you have to how science is conducted in fields distant from astronomy, particularly those that have consequences outside the literature?
September 24th, 2008 at 6:57 am
@Nathan Myers: You have written lots of stuff, but I still haven’t see anywhere what *you* would consider to be enough evidence so that one could say with confidence what causes a GRB. Please explain what exactly you are expecting.
“However, not all phenomena cooperate to make investigation easy, …”
Please explain what that is supposed to mean.
“Solid-state physicists still can’t model high-temperature superconduction, but they don’t pretend.”
That’s a bad analogy, since astrophysicists *can* model GRBs.
September 24th, 2008 at 7:38 am
@Nathan: you said “There’s no need to concoct anything exotic”. I’m very pleased to read that.
However, I’m also puzzled.
You see, the words you wrote about Phil’s blog (several of them actually) seemed to me to be extremely harsh, vitriolic, and quite unambiguous.
For example, about his use of the word “gas” where you thought he should use the word “plasma”.
For example, about his depiction of a (long) GRB as a core-collapse supernova (or similar) where you said such depiction was unscientific.
Yet, as I hope I have shown all readers as well as you, neither extreme charge seems valid.
For example, the relevant astrophysics literature is replete with the use of the word “gas” where the context makes clear “plasma” is being discussed; and thousands of astrophysics papers contain detailed examination of observations from the perspective of plasma physics.
For example, a highly-cited paper, published in 2006, presents a strong case for a (long) GRB-supernova connection.
(I should add that there is at least one Nathan Myers comment which seems to suggest consistency, to the effect that all astronomers are equally unscientific unless they append their conclusions with words about ’suspecting’ rather than ‘knowing’).
But perhaps more curious, or worrying or frustrating, is the continuing inconsistencies in the content of what you write, wrt astronomy.
For example, there are no nuances or uncertainties about the “simple fact” of the prevalence of plasma in the observable universe, and no “an honest [commentator] might announce that he or she suspects” (that “all the detectable mass in the universe, save planet(oid)s, is plasma”) caveat anywhere in sight.
Can you please clear up these apparent inconsistencies?
September 24th, 2008 at 7:43 am
Nathan wrote: “* When Todd W demanded documentary support for commonplace facts, I offered the Encyclopedia Britannica as a source he would be likely to trust. I don’t imagine anything “primary” about it.”
Indeed.
However, when I politely asked you for the specific EB references you used, following your statement that you had used them (re the definition of plasma and the source of your “simple fact” assertions), you seemed to completely ignore my request.
Further, when I pressed you - politely - for what you meant by your use of the term “dark matter”, you referred me to press releases (not papers published in relevant peer-reviewed journals).
So, would you please clarify this once and for all?
What do you regard as the primary sources for contemporary astronomy and astrophysics, as science?
September 24th, 2008 at 7:51 am
Nathan wrote: “* Electromagnetics needs to work familiarly (at least under most circumstances) out to remotest reaches for light to behave familiarly there and to get here.”
First, would you mind explaining what you mean by “electromagnetics”?
Second, how familiar are you with the lab and space-probe experiments showing that General Relativity provides a framework for accurately describing the path of ‘light’ to within the limits of the testing (’null geodesics’)? If you are not familiar, please say so and I will provide links to the relevant papers presenting the findings of the relevant lab and space-based experiments.
This is important because a consistent, and equally important, corollary to your statement would be something like “gravity needs to work familiarly (at least under most circumstances) out to remotest reaches for light to behave familiarly there and to get here.”
Third, and in advance of your answer to my first question, to what extent do you consider quantum theory needs to “work familiarly […] out to remotest reaches for light to behave familiarly there and to get here”?
September 24th, 2008 at 7:59 am
Nathan wrote: “Explanation of galactic-scale motion by assuming that only gravitation can possibly be at work has well-known problems”.
First, I have read statements about astrophysicists “assuming that only gravitation can possibly be at work” (in this context), many of them, on crackpot websites and in posts by those attacking and critiquing contemporary astrophysics. I would like to ask you to clarify this part of your comment: to what extent are you claiming that astrophysicists do not test these assumptions?
Second, do you know of any explanations of the relevant astronomical observations, that purport to be scientific, which involve assumptions other than (or in addition to) gravitation? If so, would you be kind enough to share them with readers here?
Third, what are these “well-known problems”?
September 24th, 2008 at 8:18 am
@Nathan: “Do you feel that because cosmological and astronomical results have no domestic consequences, unlike e.g. metallurgy, meteorology, and medicine, standards of evidence ought be relaxed relative to those fields? How much exposure do you have to how science is conducted in fields distant from astronomy, particularly those that have consequences outside the literature?”
Second question first: the same, very direct and personal, exposure that most of us who live in developed economies have - my PC, my internet connection, my food, my health, the transportation I use (and so on).
First question: an interesting question, but also I think a misleading one, or one more for philosophers than scientists.
Here’s one concise statement concerning “standards of evidence”: theories are the engine room of science. The key criteria for assessing a theory are:
*its internal consistency;
* its consistency with other, well-established, theories where the respective domains of applicability overlap;
and above all:
* consistency with all relevant, good observational and experimental results within the theory’s domain of applicability.
(the usual caveats apply)
Oh, and “cosmological and astronomical results” may very well “have domestic consequences”! For example, some of them made millions for certain Hollywood studios (”Deep Impact” and another film too awful to even name spring to mind), and I’m sure you’d be among the first to agree that the premise on which some of these films is based is one with “domestic consequences” well worth spending a few million euros to study, scientifically.
September 24th, 2008 at 7:33 pm
@DRD: Thank you for your extensive replies. I fear I will not be able to match you for volume. In reverse order…
I would be very impressed if you succeeded in relating cosmology to a Deep Impact event, historical or potential.
Your reply to my question, “Do you feel that because cosmological and astronomical results have no domestic consequences, unlike e.g. metallurgy, meteorology, and medicine, standards of evidence ought be relaxed relative to those fields?” didn’t actually address it. Making an exception for earth-orbit-crossing objects (which I think you will agree amount to a negligible part of present astrophysical science practice; it’s engineering now, in any case), please try again.
I shall take your reply to my question about your exposure to the practice of science in fields removed from astronomy to mean “little or none”. That’s OK, we’re all forced to specialize. My own experience is of much greater skepticism in other fields, even in those not subject to laboratory study.
The well-known problems with gravitation-only galactic- and larger scale dynamics? Disingenuity on this topic does not aid discussion. I don’t