Comments on: Avignon Day 4: Dark Matter

By: PONT Workshop in Avignon | The Oskar Klein Centre blog

PONT Workshop in Avignon | The Oskar Klein Centre blog — Wed, 27 Apr 2011 12:31:08 +0000

[...] Posted on April 27, 2011 | by Lars | No Comments Last week I was in Avignon, France, giving a talk at the PONT Workshop there. Among the people there was Sean Carroll, who some of you may remember (he visited us some 6 or 7 years ago). He runs an interesting physics blog since many years. You can find his report from the workshop here. [...]

By: m. bora cilek

m. bora cilek — Tue, 26 Apr 2011 12:50:03 +0000

hi there everyone,
finally I have solved the dark matter problem..this is no joke, believe me..
just good-old (proven) laws of physics from Newton and Einstein..no new models, funny concepts or cumbersome mathematics…I will soon post an article in one of the e-print archives..the important part is only one or two paragraphs, rest will be references etc. as that is the norm for this kind of write-ups.. you will be amazed to see how long humanity have spent in the wrong direction..very embarrassing indeed..
just note my name and wait for another 2-3 weeks..in the meantime I need your suggestions for alternative sites, to publish the article online simultaneously..
cheers.

By: Populär Astronomi - » Kommer AMS att säkra rymdfärjans plats i historieböckerna?

Tue, 26 Apr 2011 10:00:30 +0000

[...] expertbloggaren Sean Carroll skriver på Cosmic Variance kan partiklarna bakom den mörka materian komma att upptäckas inom de närmaste åren, eller så dröjer det ordentligt. Blir det snart finns goda chanser på att det blir AMS-02 som [...]

By: Matthew Saunders

Matthew Saunders — Sat, 23 Apr 2011 20:44:44 +0000

“Also, few people have strong feelings about non-gaussianities or neutrinos, but many people have strong feelings about reductionism.”

Perhaps people are more interested in what they have emotional investment in? Perhaps more people (more than scientists) can have an emotional investment in ‘reductionism’ than the other two?

(maybe it’s because Discover Mag is owned by a publisher that loves railroads?

By: Sili

Sili — Sat, 23 Apr 2011 15:54:27 +0000

But ask them what’ll happen when you shine light on a gadget with vanes that are black on one side and white and the other, in a perfect vacuum, and suddenly they’re completely quiet!

Assuming friction can be ignored, the white sides will receive a net push forward, since they reflect light – admittedly diffusely, so the push won’t be as big as with mirrors.

Of course, I’m a failed chemist, so what do I know.

ETA: Not much, I guess, now that I’ve followed the link.

By: Charon

Charon — Sat, 23 Apr 2011 04:51:27 +0000

The Greenwood Space Travel Supply Co. (Seattle) sells dark matter in a can. You should recommend some of the experimentalists go get a sample there. (Or check to see if the can is labelled with ingredients.)

By: Albert Zweistein

Albert Zweistein — Sat, 23 Apr 2011 01:36:01 +0000

Dark Matter? Moderately difficult problem.

Some hints:

Particle-LIKE? – Definitely
Very dense? – You betcha
Fit in a breadbox? – No way
Problem with assumptions? – You wouldn’t believe

Bonus hint: Ask yourself, what could produce the ARCADE-2 6x radio excess?

Game on!
Albert Z

By: Trevor

Trevor — Fri, 22 Apr 2011 12:56:32 +0000

Sean, I was thinking about your slides on entropy, and maybe the answer is in your book (purchased, but unread as of yet!), but how does the entropy calculation depend on what you take as the “closed” system? That is, the horizon today is not the same as the horizon ever was, so the entropy within the horizon today may not necessarily be reflective of an ever-increasing process.

As an example, assuming w=-1, in the far future we will be left in our “island Universe” Milkomeda (to borrow Loeb’s term for it), with scant evidence that the Universe was much larger than our patch of it. Someone doing the entropy calculation at that time would calculate a number reduced by a factor ~10^11 compared to what it would be in what we call the observable Universe today.

So can we be sure that our Universe had low entropy at early times? Could we just not be counting it all?

By: Blake Stacey

Blake Stacey — Fri, 22 Apr 2011 12:21:54 +0000

Ask people what they think about quantum gravity — or a theory of everything based on the Lie group E8 — and everyone has a strong opinion. But ask them what’ll happen when you shine light on a gadget with vanes that are black on one side and white and the other, in a perfect vacuum, and suddenly they’re completely quiet! — John Baez

By: Eugene

Eugene — Fri, 22 Apr 2011 11:47:56 +0000

Cuz you can’t calculate reductionism, but you can calculate non-Gaussianities and neutrino abundances?

By: Sean

Sean — Fri, 22 Apr 2011 09:58:14 +0000

No videos, sorry. Slides are available.

By: Paul

Paul — Fri, 22 Apr 2011 09:43:33 +0000

You’ll have to excuse me if the link is there and I’m missing it, but is the video available online?

By: Sean

Sean — Fri, 22 Apr 2011 09:28:37 +0000

Fix’d!

By: B

Fri, 22 Apr 2011 08:29:23 +0000

Intriguing!

(Small typo: “it’s” should be “its”.)