# The 4% Universe

I’ve written a review of Richard Panek’s quite good new book The 4% Universe, which has appeared at the Wall Street Journal. The main topic of the book is the supernova searches that led to what seems to be a non-zero value of the cosmological constant. It also discusses the astronomical evidence for dark matter, as well as on-going searches for a dark matter particle.

One of the most interesting themes of the book is that of the encounter between the two different cultures of particle physics and astronomy. Astronomers have begun to worry not only about a new culture of large collaborations, but about the danger of an over-emphasis on certain specific measurements of fundamental significance. For more about this, see the article by Simon White from a few years ago Fundamentalist Physics: why Dark Energy is bad for Astronomy. Now that cosmologists have their own highly successful Standard Model, they’re starting to take a look at what happened after the arrival of the Standard Model in particle physics, and worry that they too may someday become victims of their own success.

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### 12 Responses to The 4% Universe

Medieval astronomers knew that the universe is a mechanical clockwork with at least 13 epicycles.

The point is that Nature’s answers depend on how the question is posed. If you ask her about epicycles, she will answer with epicycles, even if that has little to do with the correct dynamics. And if you ask her about dark matter and dark energy, she will answer in terms of dark matter and energy. Perhaps this is the right framework. But perhaps it is not.

2. Noname says:

“Now that cosmologists have their own highly successful Standard Model, they’re starting to take a look at what happened after the arrival of the Standard Model in particle physics, and worry that they too may someday become victims of their own success.”

Really? I’d say this is rather your misinterpretation.

3. Mitch Miller says:

The White article is pretty interesting…. though I imagine some high energy experimentalists will be offended as he basically said that creative and talented people would not go into it.

It pretty much comes down to the LHC it seems. If only a single Higgs field is found astrophysics could potentially be the only possible experimental input for high energy theorists for the foreseeable future and that will have a large impact on astrophysics whether the current practioners like it or not.

4. Peter Woit says:

noname,

You’re right, I could be wrong. It’s quite possible that astronomers the world over are wetting their pants in anticipation of changing the way they work, on the experimental side joining collaborations of 3000 others to work on a $10 billion dollar piece of equipment that takes 20 years to build, and possibly measuring only one new number, while the more theoretically minded work on mind-numbingly complex and unsuccessful models, in between writing science fiction and trying to pass it off as science. Then again, maybe not. 5. Marcus says: Peter congratulations on your WSJ book review–and on the broadening of scope it represents. It would be great if you applied your informed intelligence and judgment to a wider range of topics, and would enrich what you have to say on the home topic. I’m just stating the obvious, not news to you! This is a good paragraph–saying in concentrated irony what was the overall takeaway message of Simon White’s excellent article: “…It’s quite possible that astronomers the world over are wetting their pants in anticipation of changing the way they work, on the experimental side joining collaborations of 3000 others to work on a$10 billion dollar piece of equipment that takes 20 years to build, and possibly measuring only one new number, while the more theoretically minded work on mind-numbingly complex and unsuccessful models, in between writing science fiction and trying to pass it off as science.”

So congratulations on several things (around the time of NEW #1000) and keep on truckin’

-Marcus

PS. I think Nature is more generous and holds more astrophysics surprises than collider, so it mightn’t come down to the grinding semi-stall of your ironical vision. But that’s not the point.

6. Peter Woit says:

Thanks Marcus,

Unfortunately I’m not so optimistic about astronomical evidence helping to solve the fundamental problems of particle physics. The big open issue to me seems to be understanding the origin of electroweak symmetry breaking and I don’t see astrophysics helping there. Maybe this will change, but to be clear, right now the difficult path HEP experimentalists are following seems to me the only viable one.

7. Noname says:

I can see the point of White but I don’t understand your rant about huge collaborations working on very complex experiments. When you consider the LHC, your lack of vision and appreciation is simply astonishing. I wonder why you chose Particle Physics at all. You must have been very confused. If the time comes when Astrophysics is over (not any time soon anyway) too bad for astrophysicists and so much the better for science.

8. Peter Woit says:

Noname,

Since you don’t understand my “rant”, I’ll spell it out for you:

The fantastic success of the Standard Model has made life extremely difficult for particle physics. Improving on the SM is very hard, and the LHC is the only plausible way forward. It’s a fantastic project and what people are doing there is great. But I don’t think other sciences are looking at what is going on and thinking “gee, I wish my science was in that situation with those constraints and our job was more like theirs”.

Another thing I can assure you about astronomers and others outside particle physics is that they read things like what you write here and think: “My, what a bunch of arrogant nitwits there are in particle physics, thank God my science so far has relatively few people like that.”

9. Noname says:

Thanks for your clarifications. I don’t think anybody considers the situation in your terms, though. If there is something people from other sciences might envy of particle physics is the content, not the means.

Concerning your last remarks, I don’t understand why anybody would interpret what I wrote like you did (unless they are affected by some kind of paranoia). I’d write exactly the same as above with astrophysics replaced by any other branch of science, particle physics included. You on the other hand seem to consider that the real use of science is to offer jobs to the scientists.

10. steve newman says:

i like what Thomas Larsson wrote-

“Medieval astronomers knew that the universe is a mechanical clockwork with at least 13 epicycles.

The point is that Nature’s answers depend on how the question is posed. If you ask her about epicycles, she will answer with epicycles, even if that has little to do with the correct dynamics. And if you ask her about dark matter and dark energy, she will answer in terms of dark matter and energy. Perhaps this is the right framework. But perhaps it is not. ”

I think his remark is relevant to the the 2 big ‘mysteries’- dark matter, dark energy.
The analogy is Big Bang model = mechanical clockwork with epicycles.

Dark matter is not mysterious because it is dark, (lots of matter doesnt shine like stars) — but because it is presumed to be non-baryonic. If it were baryonic, it would not be a mystery.
The gravitational mass of spinning galaxies is deemed non-baryonic only because being baryonic would contradict the limit on baryonic mass imposed by the big bang theory of nucleogenesis.

So for no other reason but to save the big bang ‘standard model’ , there needs to be 6 times as much non-baryon mass as ordinary matter..

Likewise, to save the big bang standard model from its many ‘problems’ (horizon, flatness,…) requires accepting the Inflation ‘Scenario’ (scenario,since its not quite a theory).
This in turn requires the density of the universe to be the ‘critical’ density ( omega=1), and so 73% of the universe mass must be something beyond the 4% baryon and 24% dark stuff.

“And if you ask her (nature) about dark matter and dark energy, she will answer in terms of dark matter and energy. Perhaps this is the right framework. But perhaps it is not.”

————–
Similar remarks about ‘cultural’ and ‘foundational’ obstacles to progress in physics and cosmology
were made by P.M. commenting on your book review of Yau’s “inner space”.
PM says:
September 20, 2010 at 9:23 am
….

best wishes and thanks for your reports and reviews.

11. neo says:

So what is it? “Wonderful” or “quite good”?

12. cormac says:

Nice taut review Peter, I must get the book. The only thing I might have done differently is to emphasise why there has been this astonishing convergence of the study of the world of the v large with that of the v small in recent years…but that’s cos I love this theme!