Re: Analyse This!


Igor wrote:
me wrote:
Tom Roberts wrote:
Ahmed Ouahi, Architect wrote:
More or less reflexively, he dropped into his equations something called the
cosmological constant, which arbitrarily counterbalanced the effects of
gravity, serving as a kind of mathematical pause button.

Books on the history of science always forgive Einstein this lapse, but it
was actually a fairly appalling piece of science and he knew it. He called
it ' the biggest blunder of my life '. "

From today's perspective this was not a blunder at all. Thinking
abstractly, one cannot eliminate from the Lagrangian any terms that
satisfy the symmetries required of the theory (chiefly general
covariance). If one restricts the terms to those with no derivatives
higher than the second, and requires linearity in those second
derivatives, one obtains the Lagrangian that yields the Einstein field
equation, with cosmological constant. It is the simplest non-trivial
Lagrangian that obeys the necessary symmetries.

It is, of course, up to experiments to determine the value of the
cosmological constant. Until rather recently, the value was "quite
small, consistent with zero"; with improved techniques we now measure it
to be nonzero. Einstein originally favored zero, because then the
Newtonian limit comes out correct; with a very small value, however,
deviations from Newtonian mechanics would not be detectable.


Tom Roberts

if it is consistent with zero, who is expanding the universe


thank you for this email

You don't need a cosmological constant to provide expansion. In fact,
Einstein originally used it to pull the universe back together, but

whay, was the gravity not strong enuff?

when the universe was found to actually be expanding,.he discarded it.
Or haven't you been paying attention?

is it pushed from inside or is it pulled from outside?

It's the result of the big bang.

from inside or from outside?


this because there should be more vacum and empty space
outside than it is here inside

Where's this outside that you're talking about? GR models the universe
as an open or closed spacetime manifold. There is no outside.

i tell you what, is somthing bigbang is exploding then
expanding, it does it against the outside

an imploding and contraction does it against inside

dont you know it? where have you been?


another question I have is about the big bang

if by using powerful telescopes
1. we can detect the primitive bigbang light and radiation
2. we can detect that everywhere in 3D
3. the distance to the bigbang light is increasing because expansion

are we inside the bigbang now?

In a sense. We see the effects of the big bang all around us, but the
temperature of the universe has cooled to just under 3 K.

thanks, now that you agree with inside, then an outside must
exists


because if we reverese the expantion, then we have no choice, but
being inside the bigbang

That's called the big crunch, essentially running the big bang in
reverse. It was once thought that it might be the ultimate fate of the
universe if there was sufficient total mass for gravity to overcome the
outward expansion and pull everything back together again. But it
doesn't look like it will happen due to the accelerated expansion that
we now see.

what is better, to expand or to impand?

.