Re: How can I become an expert anti-relativist?

From: N:dlzc D:aol T:com \(dlzc\) (net_at_nospam.com)
Date: 10/30/04 

Date: Fri, 29 Oct 2004 20:16:16 -0700

Dear Bill Hobba:

"Bill Hobba" <bhobba@rubbish.net.au> wrote in message
news:edCgd.3334$K7.2230@news-server.bigpond.net.au...
>
> "Bill Hobba" <bhobba@rubbish.net.au> wrote in message
> news:mHBgd.3296$K7.1112@news-server.bigpond.net.au...
>>
>> "MP" <pet.antispam@onlinehome.de> wrote in message
>> news:cltt9g$7fp$2@online.de...
...
>> > As the scalefactor of the universe is always positive, it is
>> > easy to see, that if the acceleration is positive (accelerating
>> > universe), rho + 3 P must be negative, and the strong
>> > energy condition is violated. It is as simple as that.
>>
>> Equation 5.2.13 says second derivative of
>> a/a = - 4 Pi /3 (rho + 3 P) and as Wald points out later
>> (page 99) the second derivative must be negative (ie the
>> universe is expanding at a faster rate the further we go back
>> in time) thus the LHS is negative and fully compatible with
>> the strong energy condition. Yes I see how during inflation
>> when the expansion was accelerating it was violated - but
>> during that period are we sure that even GR was true.
>
> Ahhh. I think I see where the poster is coming from now.
> He is referring to the new evidence we have that the
> expansion may be speeding up rather than slowing down.
> Note the analysis giving equation 5.2.13 is based on a
> zero cosmological constant - all this implies is that the
> cosmological constant is probably not zero. Thus the
> positive energy condition can still be satisfied.

You guys are way over my head but, here is some evidence that expansion may
have currently slowed...
URL:http://arxiv.org/PS_cache/astro-ph/pdf/0302/0302008.pdf

I think it is refreshing that you get to have a solid discussion about
something other than other peoples fantasies, Bill.

David A. Smith

David A. Smith

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