Comment by carterac | Hacker News Reader

Comment by carterac | Hacker News Reader

Reasons I am skeptical: the conclusions have extremely profound implications for physics yet this hasn't appeared on my radar through an established journal.

Reasons this is believable: It answers two major questions I have with the current model.

1. Cosmic acceleration. This has been written off as the result of "dark energy." A total cop out, and worst of all, it violates the laws of thermodynamics since energy is being added to the system.

2. The concentration of positive amounts of mass during early stages of the universe should have created a black hole.

Overall I'm still skeptical, but on the other hand, this is a more believable theory that addresses those questions than I have heard so far. I'm very curious if anyone else thinks it may have merit on this basis. I would also love to know if anyone can independently validate the accuracy of the simulations.

The expansion of the universe does not violate energy conservation. Energy conservation says \del_b T^ab = 0, where T is the stress-energy tensor. The metric tensor in Einstein's field equations is covariantly constant (\del_b g^ac = 0), and the cosmological constant obviously isn't going anywhere either, so adding the extra term doesn't have any effect with regards to energy conservation. Any reasonable textbook on general relativity will have a proof of this pretty early on.

IANAP.

The article says the simulations took 60 hours on a "486/DX-33". That brings back memories. Anyone could rerun the simulations on a modern PC by writing about 50 lines of code and 10 minutes of runtime.

While it is easy to criticize odd-ball theories, I think it is more fun to try to think of tests that might support them or disprove them.

I decided to try just that (with html canvas). Its probably WAY off, but it was fun to mash up. http://thecowch.com/media/demo/index.html

edit: just a disclaimer, im no genius at physics and Ive probably misinterpreted the OP's post or made some other gross flaw in this sim.

Note that pure Einsteinian General Relativity does not conserve energy -- even without a cosmological constant. Sometimes people fake it using tortuous analogies that only hold if their spacetimes are nearly flat, but it fails to hold in the presence of curvature.

The first link on Google for the relevant keywords is http://www.phys.ncku.edu.tw/mirrors/physicsfaq/Relativity/GR..., which lays it out nicely.

Yes, I think it has merit.

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