Comments on: M83′s nursing arms

By: DeiRenDopa

DeiRenDopa — Sat, 13 Sep 2008 13:19:16 +0000

@Nathan: I will mention that the “gas” could not “slam” (presuming that’s what’s really going on at all) if it were not ionized; it would just pass right through, because it’s what in the lab we would call a “hard vacuum”, and gas particles barely interact unless they actually collide.

OK, I’ll bite; what’s the mean free path of a gas particle (atom or molecule) in the ISM (interstellar medium)? Just an order of magnitude estimate will do thanks.

Oh, and I checked and Phil’s blog does not use the word “slam” … where did you quote it from, may I ask?

By: Neil Williams

Neil Williams — Thu, 04 Sep 2008 09:55:15 +0000

@ Sirian, diderick – same thing happening with the feedblitz email updates – back to normal please Phil.

By: Nathan Myers

Nathan Myers — Thu, 04 Sep 2008 01:58:48 +0000

@shane: Everybody who reads comments at all knows, now, that Phil’s pulling a fast one. I will mention that the “gas” could not “slam” (presuming that’s what’s really going on at all) if it were not ionized; it would just pass right through, because it’s what in the lab we would call a “hard vacuum”, and gas particles barely interact unless they actually collide. Plasma particles, by contrast, interact at macroscopic distances, so it really matters that, and how much, these “gases” are ionized.

By: diederick

diederick — Wed, 03 Sep 2008 16:53:26 +0000

I’m with Sirian on this. Google reader is a lot more convenient than keeping bookmarks, but if I only get the first few lines of every post I can’t use it. Usually when you change anything on your blog you tell your readers about it and what your reasons are. This is a sudden and unannounced thing, so I’m guessing the Discovery guys are responsible and didn’t tell you. I hope you can change it back.

By: tom

tom — Wed, 03 Sep 2008 16:15:58 +0000

wow.
When Hubble splashes in a few more years, we won’t even need a telescope above the atmosphere!

By: Gary Ansorge

Gary Ansorge — Wed, 03 Sep 2008 13:42:38 +0000

CanadianLiegh:
At the time I read Tau Zero,(two weeks ago) I had just discovered WOWIO and was able to read it online for FREE.!!! A few days later, I received my copy of Greg Bears book City at the End of Time, which posits the exact opposite scenario, in which humans 100 trillion years down the line are struggling to survive the dissolution of all matter, etc. I really liked the juxtaposition of those two points of view,,,

Of course, Andersons book was written long before we discovered the accelerating expansion of the universe. It was based upon the cyclical theory of the universe.
Gregs story wonders what it would be like when that expansion becomes really significant,,,

Cool books!

GAry 7

By: IVAN3MAN

IVAN3MAN — Wed, 03 Sep 2008 09:39:32 +0000

I’ve already given up on the RSS (Really Slow Service!) Feeds because they tend to arrive several hours late at the best of times. Far better to bookmark a direct link to Bad Astronomy on one’s browser toolbar.

By: Turb

Turb — Wed, 03 Sep 2008 08:44:20 +0000

Even galaxies have myspaces.

http://www.myspace.com/m83

By: Sriram

Sriram — Wed, 03 Sep 2008 08:24:38 +0000

Nice Pic.. But Your RSS Feeds don’t show your full posts!! Can you please revert it back the way it used to be so that i can read the full article from my Feed Reader..

Thanks Phil..

By: kuhnigget

kuhnigget — Wed, 03 Sep 2008 05:37:20 +0000

Can we simply agree it’s bloody far away?

Oh, but then again by cosmic standards I suppose it’s not, really.

Never mind.

By: IVAN3MAN

IVAN3MAN — Wed, 03 Sep 2008 04:42:32 +0000

llewelly:

Pshaw. Real physics geeks measure distance using the Planck length. M83 is 9,400,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 Planck lengths away from us.

Pah! Physics geeks are too obsessed with a blackboard & chalk; they ought to get out more with a telescope and do some real stargazing. Furthermore, real astronomers prefer to measure distances between the stars and galaxies in parsecs: 1 parsec = 3.26156 ly. Therefore, the distance of Messier 83 from the Sun/Earth is ~4599026.233 pc.

By: Samu

Samu — Wed, 03 Sep 2008 03:01:20 +0000

llewelly- Actually, real physics geeks measure the distance as 9.4×10^57…. we don’t know the accuracy of that measurement enough to add that many significant digits.

By: shane

shane — Wed, 03 Sep 2008 02:56:32 +0000

I’m surprised that no-one (Nathan) has popped in to say that where the BA mentions gas he means plasma.

CanadianLeigh, I know what you mean about hoarding old books. I have been politely asked to put all my old books into storage. I’m allowed to keep them, just not stacked up around the apartment. So I’m finally getting the chance to catalog some old gems I’d forgotten I’d read including a stacks of Poul Anderson, Asimov, Clarke, Heinlein and other grand masters. Found some crap too. Who new I actually own something by Jackie Collins.

By: shane

shane — Wed, 03 Sep 2008 02:46:16 +0000

What size plank though? 4×2?

By: llewelly

llewelly — Wed, 03 Sep 2008 02:18:22 +0000

Ken B:

in the case of galaxy M83, from 15 million light years away: 150 quintillion kilometers (90 quintillion miles) remote

Those numbers just don’t do it justice. You need to say something like 5,900,000,000,000,000,000,000,000 inches!

Pshaw. Real physics geeks measure distance using the Planck length. M83 is 9,400,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 Planck lengths away from us.

By: kuhnigget

kuhnigget — Wed, 03 Sep 2008 01:31:22 +0000

If you squint really hard, you can just make out the infinite stack of turtles that is supporting that galaxy….

By: Daniel

Daniel — Wed, 03 Sep 2008 01:17:22 +0000

lets see. Creationism + Evolution = The truth lies in the middle. Nice pic

By: Davidlpf

Davidlpf — Wed, 03 Sep 2008 00:29:12 +0000

How about that neutral hydogen.

By: Todd W.

Todd W. — Tue, 02 Sep 2008 23:39:54 +0000

@Davidlpf

Lie down on this couch. Now, tell me about your relationship with your father…

By: Davidlpf

Davidlpf — Tue, 02 Sep 2008 23:38:30 +0000

I hope nobody tries get psychological profile from what I post here.

By: Todd W.

Todd W. — Tue, 02 Sep 2008 23:34:44 +0000

@John

Whom are you addressing?

By: John

John — Tue, 02 Sep 2008 23:34:12 +0000

your = creationists

By: John

John — Tue, 02 Sep 2008 23:33:06 +0000

Your concept of God has nothing to do with reality, it only explains your psychology

By: Davidlpf

Davidlpf — Tue, 02 Sep 2008 23:29:16 +0000

(I have to before someone else does)
I thought this blog was for pretty pictures from space and not making fun of religion.
(now back to the regular posts)

By: Todd W.

Todd W. — Tue, 02 Sep 2008 23:17:14 +0000

@Davidlpf and IVAN3MAN

No, no. You’re getting it wrong again. The Creator has always been and and will always be. He/She/It exists beyond time. There is no need for anyone/anything to create the Creator. You clearly need guidance. Might I suggest paying a visit to your nearest YEC church.