Comments on: Don’t Be Fooled by w!

By: How Are We to Make Progress With w? | Cosmic Variance

How Are We to Make Progress With w? | Cosmic Variance — Tue, 02 Aug 2005 12:34:56 +0000

[...] One of my primary research interests over the past six or seven years has been the question of what is driving the accelerated expansion of the universe. As I’ve mentioned before, cosmologists now have a clear and surprising accounting of the energy budget of the cosmos. Multiple techniques provide compelling evidence for (roughly) 5% baryonic matter (the stuff of which you are made, that makes up planets and stars, and which occupies much of the space between them), 25% dark matter (a mysterious, weakly interacting component that clumps together and provides the immense gravitational wells into which regular matter can form and combine with dark matter to make galaxies) and a whopping 70% dark energy, with negative pressure, sufficiently negative to cause the expansion of the universe to accelerate. [...]

By: island

island — Sat, 30 Jul 2005 18:28:52 +0000

The physical effects of the Big Bang created numerous principles and laws that have yet to be broken in spite of a lot of projections and speculation about the eventual and final fate of the usable energy of our expanding universe.

The inevitable heat death of the universe is one of the more obvious projections of an expanding “entropic” universe, but this conclusion doesn’t completely justify the fact that the extremely small positive value of the cosmological constant means the big bang actually resulted in a near perfect balance between runaway expansion and gravitational recollapse, which actually puts the universe about as far away from the tendency toward heat death as you can possibly get, and yet still be heading in that direction. The principle of least action says that it is no coincidence that this near-perfectly symmetrical configuration is also the most energy-efficient means for dissipating energy, because this means that tendency toward “heat-death” is most economically restricted to the most-even distribution of energy possible.

The universe actually expresses a grand scale natural preference toward the most economical form of energy dissipation, so if the second law of thermodynamics is telling us that the entropy of our expanding universe increases with every action, then the anthropic principle is telling us that this will occur by the most energy efficient means possible, since the flatness of the universe is one of the many coincidentally ecobalanced requirements of the principle.

If the second law of thermodynamics points the arrow of time, then the anthropic principle determines that time is maximized.

By: Mark

Mark — Sun, 24 Jul 2005 22:36:34 +0000

erc – I don’t really know; I guess it’s just a convention. when I give talks I usually refer explicitly to students and postdocs with the idea that they will be on the job market and it’s good a) to advertise their work and b) make it clear they will be available (either that year or soon). In the case of my own students in particular, I’m often just plain proud that they are studying with me and at our University (and on some level I guess I want people to know that).

You certainly don’t have to give up the spellings. I think I just got tired dealing with spell checkers that don’t like the UK versions and don’t feel strongly about a “correct” way of writing things.

By: erc

erc — Sun, 24 Jul 2005 20:16:38 +0000

When in doubt, go for “ise”. Also, look out for non-words, like “scrutinization” -heard on the “Today” programme on Radio 4(!), nonetheless (that should be “scrutiny”, for any one in doubt) – where the influence of those across the pond is evident…

What about my first question?
E

By: Clifford

Clifford — Sun, 24 Jul 2005 20:04:31 +0000

erc – See my comment on that very issue in the comments on this thread .

Cheers,

-cvj

By: erc

erc — Sun, 24 Jul 2005 19:59:07 +0000

Two points, both at a tangent to the original post, I’m afraid.

1) Why are students always referred to as such? (..his student, Mark Hoffman..)The relative seniority of anyone else mentioned is never stated. (NB I don’t mean to sound like I have an issue with this; I’m just interested.)

2) Mark, will I _have_ to give up my English spellings when I move to the US? I really hate the replacement of s’s with z’s (that’s ‘zed’ not ‘zee’, by the way).

Regards,
E

By: amanda

amanda — Sun, 24 Jul 2005 12:03:09 +0000

By: Anonymous

Anonymous — Fri, 22 Jul 2005 15:07:45 +0000

I see no harm in calling the dark energy “dubya” since

1) No one understands it
2) It pushes the world apart instead of pulling it together
3) It started dominating recently and may well do so forever

By: Mark

Mark — Fri, 22 Jul 2005 02:33:53 +0000

Like the “u” in “favourite” Trevor. Living in the US and collaborating with lots of US physicists, I’ve gradually given up on these spellings myself, but secretly hate that I’ve done it.

By: Trevor

Trevor — Fri, 22 Jul 2005 02:28:38 +0000

You got me on this one.

Your favourite right-wing commenter