I received an unusual email from, of all people, the Nobel Prize website editor! He was notifying me that the Nobel Prize folks have started a new series of videos where people get a chance to ask questions of Nobel laureates, who will then answer them on YouTube. Pretty cool, and something I heartily approve of. I love it when people get more contact with scientists, especially ones who are doing research that qualifies them for the Nobel!
They started the series off with astronomer John Mather, the Principal Investigator for the James Webb Space Telescope, who won the prize for his work with COBE, the Cosmic Background Explorer. I worked on that project very briefly, and over the next few years had the pleasure of working with John, who is just about as nice as he can be.
Here’s an example of one of the questions — what happened before the Big Bang — with John’s answer:
There are quite a few more, too. If you have an account on YouTube, you can subscribe to the Nobel channel and find out when they will do the next laureate Q&A, too. Very cool.
December 28th, 2009 at 11:30 am
Thank you for the heads up! Absolutely a channel I will be subscribing to. By the way, is there a Bad Astronomer channel there? If not, why?
December 28th, 2009 at 11:57 am
Cue the anti-Obama yokels and their sad misconceptions regarding the Peace Prize AND Big Bang Theory… two things they absolutely despise.
December 28th, 2009 at 12:16 pm
Hey Phil,
Thought I would let you know I got your book for Christmas! My girlfriend knows that I follow your blog and that I was interested in reading it. I’ll let you know when I’m done.
Keep up the good work!
Greg
December 28th, 2009 at 12:25 pm
There used to be a BA podcast, but it seems Phil did not have enough time to keep going with it.
Anyway, he’s getting his own TV show now…
December 28th, 2009 at 12:27 pm
@ Damon:
Actually, I love the Big Bang theory. But I sure as heck would like to ask the Nobel Peace Prize winner a thing or two.
BTW, what are my misconceptions?
December 28th, 2009 at 1:13 pm
My question does not deserve a Nobel laureate answer, I think. Look at the moon when it is half-full. The terminator (the line between the sunlit and dark faces) is then a straight line. Bisect this line, and draw a perpendicular to it. According to MY understanding of optics, this perpendicular should point directly to the source of the illumination – the sun. It does not. Or at least it appears to not point there. It is massively off target, by perhaps 35 degrees. What is going on that what I think should be seen here, is not so ?
December 28th, 2009 at 1:31 pm
Hey, Damon, I LOVE the Big Bang Theory! I mean, seriously, what’s not to like. As for what happened before I really want to know. As for the risible Obama “Peace” Prize, perhaps we could put it to these Nobelists, “Obama’s prize. What’s that about?”
December 28th, 2009 at 2:08 pm
1. Larian LeQuella Says:
Thank you for the heads up! Absolutely a channel I will be subscribing to. By the way, is there a Bad Astronomer channel there?
Of course there’s a “TheBadAstronomer” channel, have it right in my Subscriptions along with Thunderf00t, Monty Python, misterdeity, JamesRandiFoundation, Captain Disillusion, Cinematic Titanic, Shout!Factory, something weird, and obscure movies. (and more)
J/P=?
December 28th, 2009 at 2:39 pm
@ Brian:
Huh?
December 28th, 2009 at 4:46 pm
Brian,
The line at the Moon is a tangent. You need to follow the celestial geodesic, which will be a curved path, an arc, between the Moon and the Sun on the celestial coordinate system.
December 29th, 2009 at 1:15 am
Hey! Whatever happened to “Space-time itself came into existence in the Big Bang, so ‘before the Big Bang’ doesn’t mean anything”? Do we now know for sure that something like the Loop Quantum Gravity theory, which does allow (or even predict (postdict?) that there was) a time before the Big Bang, will replace current theories? Fascinating.
December 29th, 2009 at 4:00 am
Pardon ? The line at the moon is a tangent ? Which line, and a tangent to what arc ? A curved path would be appropriate for the surface of a sphere. That is not what we have here. Light travels in straight lines. I don’t see how a curved line could be explained as being the answer. Do you have a diagram we could all look at that might explain your point ?
December 29th, 2009 at 4:19 am
Light is bent by gravity.
December 29th, 2009 at 6:27 am
Brian, you’re looking at a 2D projection of 3D objects. You can’t assume the geometric rules still hold there as they do in 3D. Consider that a 2D projection of the moon or the sun only tells you they lie somewhere on a line starting from your eye point, and that depending on the position on that line they will be lit differently.
December 29th, 2009 at 7:24 am
Brian,
The light is traveling a straight path (to a close classical approximation). What I’m talking about is the projection on the celestial sphere.
Consider the following. Let’s say the Moon will eclipse the Sun in a couple of weeks. Right now the tangent seemingly points well-away from the Sun, which is way over at another patch of sky. But as the days pass the Moon and the Sun get progressively closer together, and the tangent gets progressively closer to pointing straight through the Sun. At the instant of the eclipse there’s no difference in angle at all.
December 29th, 2009 at 9:02 am
Brian, I’ve just compared the position and appearance of the moon to where it should be, and, guess what ? It is really there. At the correct position in the taurus constellation. Size, color rotation and shadow is also correct. I suppose you’d better learn how to measure angles properly before you start asking silly questions
December 29th, 2009 at 9:41 am
Okay! Okay! I confess! I was secretly testing my Moon-o-Matic™ Space Illuminator the other night and sort of messed up the natural lighting arrangement. Sorry. Won’t happen again.
BTW, tomorrow I will be trying out my Flat Earth-o-Tron™, so…you might want to hold off on any long-distance travel. That last step is a doozy.
December 29th, 2009 at 10:23 pm
I thought it was a very reasonable question, Brian. Just sayin’.
In other news, John Mather rox my astronomy lovin’ sox.
December 30th, 2009 at 4:35 am
Tangent ? What tangent ? I asked this once already and have not had a response. A tangent is a straight line that touches an arc at one point but does not cross it. What arc ? Some of the responses here lead me to believe the authors have not bothered to look into the sky to see what I described. As for the 3D versus 2D, at the scale involved, any 3D effects are minute. Yes, gravity does bend light, but only over a massive distance, and there is no object heavy enough in the solar system out as far as the earth-moon pair that would bend light by 35 degrees. As an experiment, set up a point source light down a long, darkened hallway, position a small sphere (e.g. a basketball at the same height as the light source) at an intersecting hallway, and stand in the intersecting hallway so you can see the basketball but not the point source of light. See if you can manipulate any part of the environment so that the terminator on the basketball is not at 90 degrees to the floor of the hallway, and therefore to the beam of light.
December 30th, 2009 at 8:04 am
Well, Brian, we’re at the point were you need to explain how you measured the angle.
December 30th, 2009 at 9:52 am
See if you can manipulate any part of the environment so that the terminator on the basketball is not at 90 degrees to the floor of the hallway, and therefore to the beam of light.
Uh…..if you do your own experiment, you will see the terminator on the basketball appears as an ARC curving around the surface of the ball at every viewing angle except when you are at 90° to the ball/light.
So I guess your thought experiment has just answered your original post? It’s all about the viewing angle.
December 30th, 2009 at 11:03 am
kuhnigget,
He’s not talking about the shape of the terminator. He means that the illumination doesn’t appear to be falling directly from the Sun, but rather from off to one side of the Sun.
December 30th, 2009 at 1:42 pm
@ TEL:
Maybe so, but that’s not what his thought experiment proves. It will show that the “terminator” is an arc whose degree of curvature depends on the angle from which you view it. Which tends to make his “What arc?” question kind of dubious.
His original post asked about the direction of the light source, based on the appearance of the terminator as a straight line. But as others have correctly pointed out, he is treating the geometry of the situation as if it were a flat, 2-d plane, when in order to explain why the sun is indeed the source of the moon’s illumination (as opposed to what? no one has politely asked) you need to consider the 3-dimensional space in which we’re viewing the two objects.
But I suspect our friend Brian has something else going on, and just hasn’t got around to “enlightening” us as to its nature.
Brian?
December 30th, 2009 at 2:53 pm
kuhnigget,
Brian only used the half-Moon terminator for its simplicity. It conveniently paints the Moon’s pole-to-pole line segment without undue elaboration. The segment is present even for phases before and after the second quarter; it’s just a matter of connecting the cusps. From this Brian stipulates bisecting the segment with another, orthogonal line. The orthogonal line, he says, doesn’t point straight toward the Sun.
I personally think it’s just an artifact of projection if it’s anything at all (otherwise, where does Brian think the light is coming from?); but at this point it’s up to him to show how he came by this.
December 30th, 2009 at 3:34 pm
The orthogonal line, he says, doesn’t point straight toward the Sun.
Yes, that would be the effect of my Space Illuminator. Again, I do apologize for the confusion/mental anguish.
December 30th, 2009 at 8:48 pm
Kuhnigget, is your Moon-o-matic a reproduction of the device NASA used to fake the shadows on the moon-landing pictures?
Oh, yeah, I would try to explain it to Brian, but my brain always hurts when I try to visualize 3D stuff. Then it explodes.
December 30th, 2009 at 9:42 pm
@ Buzz:
NASA stole my designs. Then they launched a big conspiracy to cover it up and plant rumors that I was nothing but a crank who hangs out on internet blogs, annoying people and generally causing trouble.
Where’s my tinfoil, dammit?
March 4th, 2010 at 7:24 am
We have a new YouTube session of “Ask a Nobel Laureate” now with Albert Fert, awarded the Nobel Prize in Physics 2007 for his discovery of Giant Magnetoresistance, which forms the basis of the memory storage system found in your computer and mp3 players. Deadline for questions is March 19, 2010. http://www.youtube.com/thenobelprize