Living in Interesting Times
Eighty five years ago our universe
Consisted of a single galaxy, our Milky Way.
Now we know there are over 400 billion galaxies!
The three pillars of the big bang, are
(1) The Hubble Expansion,
(2) The existence of the CMB radiation, and
(3) Observations of the abundance of light elements.
Because of cosmic acceleration,
All galaxies outside of our
Own bound cluster will disappear.
With no galaxies there will be
No tracers of the Hubble expansion.
Interestingly, with no such tracers,
All evidence of the existence of dark energy,
And an accelerating universe will also disappear.
The only period when dark energy is detectable is now.
At much earlier times it had a negligible effect upon the expansion,
And at late times it drives out all tracers of the expansion.
The CMB becomes unobservable even in principle,
As the peak wavelength is driven
To a length larger than the horizon.
The final key bit of evidence for the Big bang
Rests crucially on the fact
That relic abundances of deuterium
Remain observable at the present day…
But, by then, both the QSOs and the Lyman- Systems
Will have redshifted outside of the horizon.
What will observers of the far future infer then?
Their picture of the universe
Will not be significantly different
Than that which Einstein had
When he developed general relativity:
A static universe in which our galaxy
Was surrounded by eternal empty space.