http://krauss.faculty.asu.edu/
http://online.wsj.com/article/SB124597314928257169.html
My practice as a scientist is atheistic. That is to say, when I set up an experiment I assume that no god, angel or devil is going to interfere with its course; and this assumption has been justified by such success as I have achieved in my professional career. I should therefore be intellectually dishonest if I were not also atheistic in the affairs of the world.
— J.B.S. Haldane
“We are all fucked” by Lawrence Krauss
A mistery story… about the “mysterious stuff” that dominates nature.
General theory of relativity was brought forward by Einstein in 1916.
Which basically described how space was not constant but could expand and contract, a dynamic entity, which curves in the presence of matter.
This disagreed against the observation that the universe was static and eternal. Around forever and forever in the future.
Also, similar challenge that the Newtonian’s gravity theory faced against a static universe. Gravity sucks, it never pushes.
Stars would never be at the same spot. Gravity would pull them together at some point.
So. The current observation of a static [Curvature = Energy – Momentum] did not work for Einstein.
He added an extra term to the Curvature part of the equation to make it work in the General Theory of Relativity, an element stated as “The Cosmological Term”, which could explain the dynamic status of space.
[Curvature – The Comsological Term = Energy – Momentum]
This element would produce a small repulsive force through empty space. So small not to have effect at Newton’s law solar systems level, but a gigantic effect at Galaxy level, and keep them apart.
But he soon realized in 1923 this was a problem.
If the universe was expanding already, then you dont need a “The Cosmological Term” cosmological constant to prove the expansion anymore.
Gravity can then probably universally slow down the expansion.
It became evident the question was now. Is the universe expanding. And. In relation. Is there enough gravity to stop the expansion.
Would the universe end crashing on itself in a bang. Or whimpering and expanding away.
But, by 1929 Edward Hubble discovered the universe was indeed expanding, as Einstein predicted.
Looking at the galaxies around us, the ones twice as far away were moving twice as fast. Those three times far away were moving three times as fast. And so on.
Velocity was proportional to distance.
This agreed with observations that could be made theoretically from “outside” our universe.
At any time interval, galaxies would expand in all directions. Even though, for an untrained observer inside any point of the universe, all galaxies would move away from the point of observation in a manner proportional to distance. Making the untrained observer believe he is indeed at the center of the universe.
But. It appears there is no center to the universe. (?)
The way Hubble discovered this expansion is that, same as sound of a moving train, light gets stretched the further it has to reach.
And the longer the light wave, the redder end of the light spectrum shows up. So. The further the galaxies are, the more they appear red shifted to us.
We now knew the universe was expanding somehow and defining the velocity was easy because of the red shift’s analysis.
But how do you know distance?
We can measure distance to a light if we knew the power of a light shining into a light-meter and by analysing the decay of the light when this reaches the light-meter.
As light decays 4 times with the doubling of the distance.
We had to apply this to the universe by finding what was referred to as the holy grail of last century’s cosmology, a “standard candle”. A source of light in the universe with a known brightness.
They finally found one. An exploding star.
Literally “everything” comes from an exploding star. The brightest light in the universe.
We are all star dust. All the elements that matter for evolution were created in the nucleus furnaces of a star. Even the atoms in your left hand could be coming from a different star than the ones in the right hand.
In many ways. The stars died so we could be here today.
Just only one such explosion seem to appear every hundred years per galaxy.
But there are enough galaxy in the sky to see a hundred thousand galaxies inside the shape of a dime you hold in front of the darkest spot of the night sky.
In that region you could 10 lights explode in one night.
For this. After 75 years, we can now deduce the rate of expansion of the universe with a margin of error of 10%.
And extremely accurately, almost to 4 decimal points, deduce the age of the universe to 13.72 billion years.
So. By this time, 1929, Einstein realized “The Cosmological Term” did not relate to the curvature part of the general theory of relativity equation.
He tried to remove it.
But it was not that easy.
“The Cosmological Term” on the curvature side of the equation was a geometric quantity.
Moving it on the energy and momentum side of the equation it became a new contribution to the very energy and momentum of the universe.
[Curvature = Energy – Momentum + The Comsological Term]