Einstein's Cosmological Constant: Push or Pull?

In summary, there is some confusion about Einstein's prediction of the expanding universe and the role of the cosmological constant. Some sources suggest that he inserted the constant to represent a force pushing the universe out, while others claim it was to represent a force pulling it back in. However, it seems that the prediction of General Relativity was that the universe could not be static, leading to the introduction of the cosmological constant. This could be interpreted as stopping contraction or allowing for either expansion or contraction. Some sources credit Einstein for predicting the evolving universe, while others use the term "expanding" loosely.
  • #1
Cycklops
2
0
Was watching some documentaries and got confused about something.

People say that Einstein unintentionally predicted that the universe was expanding, and that he inserted the cosmological constant to represent a force pulling it back in. But other sources seem to imply that the universe was supposed to be collapsing under gravity, and he inserted the cosmological constant to represent a force pushing it out (which is what it seems to represent today).

So which is it? The idea of the cosmological constant being a force pushing against gravity makes the most sense, but that seems to contradict the normal claim that Einstein was the first to find that the universe should be expanding.
 
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  • #2
Cycklops said:
People say that Einstein unintentionally predicted that the universe was expanding, and that he inserted the cosmological constant to represent a force pulling it back in.
What people? Please provide references.

The prediction of GR was that the universe could not be static, which was the reason for introducing the cosmological constant. Had it not been introduced, then a direct consequence would be that the universe either expands or contracts (or is just in the transition between the two).
 
  • #3
Orodruin said:
What people? Please provide references.
One example is this interview with Ed Copeland...

At 0:10, he says "Einstein was really quite resistant to the idea that the universe is expanding, and he worked very hard to stop it."
He then refers to the universe "evolving" instead, but at 10:40 he says "for this to work, for him to stop the universe from expanding..."


The prediction of GR was that the universe could not be static, which was the reason for introducing the cosmological constant. Had it not been introduced, then a direct consequence would be that the universe either expands or contracts (or is just in the transition between the two).
That makes some sense, which would imply then that people are just giving Einstein credit for predicting that the universe would be evolving, and some people use the term "expand" when in actuality the cosmological constant was either something that stopped contraction or something that could stop either one depending on how you define it?
 

1. What is Einstein's cosmological constant?

Einstein's cosmological constant is a term that was added to his general theory of relativity equations in order to account for a static universe. It is typically denoted by the Greek letter lambda (Λ) and has the units of inverse length squared.

2. Did Einstein believe in a static universe?

Initially, Einstein believed in a static universe and used the cosmological constant to account for it. However, after observations by Edwin Hubble showed that the universe is expanding, Einstein abandoned the constant and referred to it as his "biggest blunder."

3. Is the cosmological constant a push or a pull?

This is a debated question and there is no clear consensus among scientists. Some argue that the cosmological constant acts as a repulsive force, pushing galaxies away from each other and causing the universe to expand at an accelerating rate. Others argue that it is a type of gravitational pull, causing matter to clump together and form structures like galaxies and clusters.

4. What is the current understanding of the cosmological constant?

The cosmological constant is now seen as a component of the larger theory of dark energy, which is thought to be responsible for the accelerated expansion of the universe. It is still a subject of ongoing research and there is much that is still not fully understood about its nature and effects on the universe.

5. How does the cosmological constant affect our understanding of the universe?

The cosmological constant has played a significant role in shaping our understanding of the universe, from Einstein's initial attempts to explain a static universe to its current role in the theory of dark energy. Its effects on the expansion of the universe have also led to new questions and theories about the ultimate fate of the universe.

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