Gravity & Dark Energy: Newton, Einstein & Beyond

In summary, the discussion revolves around the mystery of gravity and dark energy, and the lack of understanding on how gravity forces mass and energy to follow geodesic lines. The question also delves into the speculation that the existence of matter/energy may lower the pressure of dark energy, causing space-time to flow towards matter similar to a gas moving towards a low pressure region. However, personal theories and speculation are not allowed for discussion.
  • #1
Dennis Plews
36
4
TL;DR Summary
Are Gravity and Dark Energy the same?
What gravity is, as pointed out by Newton and Einstein, is still a mystery. Adding to that conundrum is dark energy which continues to inflate the cosmos. Both Newton and Einstein, and every one else as far as I am able to discern, assume that gravity works by drawing massive bodies together through space-time warping. I have not yet been able to find any writer who can explain how gravity forces mass and energy to follow geodesic lines.

Adding to my confusion is the finding that dark energy causes space-time to expand, most rapidly in the intergalactic voids and at the edge of our ability to see. It’s opposite sign to that of gravity may be explained by the Friedman equations but I have a speculation that I have not seen addressed or posited anywhere.

In one of the science books I have read I recall that Einstein is quoted as having said that “matter is lumpy bits of space time.” Assuming that to be true and adding the ideal gas law to the mix, I have wondered whether the existence of matter/energy lowers the pressure of dark energy in its immediate vicinity so that space-time moves towards the matter in a flow akin to that of a gas moving to a low pressure region from a high pressure region. Can anyone direct me to a paper that addresses this speculation?
 
Physics news on Phys.org
  • #2
Dennis Plews said:
Summary:: Are Gravity and Dark Energy the same?

What gravity is, as pointed out by Newton and Einstein, is still a mystery. Adding to that conundrum is dark energy which continues to inflate the cosmos. Both Newton and Einstein, and every one else as far as I am able to discern, assume that gravity works by drawing massive bodies together through space-time warping. I have not yet been able to find any writer who can explain how gravity forces mass and energy to follow geodesic lines.
Adding to my confusion is the finding that dark energy causes space-time to expand, most rapidly in the intergalactic voids and at the edge of our ability to see. It’s opposite sign to that of gravity may be explained by the Friedman equations but I have a speculation that I have not seen addressed or posited anywhere.
In one of the science books I have read I recall that Einstein is quoted as having said that “matter is lumpy bits of space time.” Assuming that to be true and adding the ideal gas law to the mix, I have wondered whether the existence of matter/energy lowers the pressure of dark energy in its immediate vicinity so that space-time moves towards the matter in a flow akin to that of a gas moving to a low pressure region from a high pressure region. Can anyone direct me to a paper that addresses this speculation?

You could start here:

https://www.physicsforums.com/insights/inflationary-misconceptions-basics-cosmological-horizons/

Most of your questions are based on misunderstanding modern cosmology.
 
  • #3
Dennis Plews said:
Both Newton and Einstein, and every one else as far as I am able to discern, assume that gravity works by drawing massive bodies together through space-time warping.

That's not how Newton said gravity works. He said gravity was a force.

Einstein's General Relativity includes solutions in which massive bodies are attracted to each other because of the spacetime geometry caused by their mass, but those aren't the only solutions it includes.

Dennis Plews said:
I have not yet been able to find any writer who can explain how gravity forces mass and energy to follow geodesic lines.

You must be joking. Do you know how many GR textbooks there are?

Dennis Plews said:
dark energy causes space-time to expand

No, it doesn't. Spacetime doesn't expand or contract. It just is.

The effect of dark energy is sometimes described as causing an accelerated expansion of space, but this is only a heuristic picture and can be misleading if taken too literally.

Dennis Plews said:
It’s opposite sign to that of gravity may be explained by the Friedman equations

For "may be" read "is".

Dennis Plews said:
I have a speculation that I have not seen addressed or posited anywhere.

Please review the PF rules regarding personal speculation. We do not discuss personal speculations here.

Dennis Plews said:
In one of the science books I have read I recall that Einstein is quoted as having said that “matter is lumpy bits of space time.”

Please give a specific reference (and to me by PM, since this thread is going to be closed). Just a vague allusion to "one of the science books I have read" is not sufficient.
 
  • #4
The OP question is based on personal speculation and is off limits for PF discussion. Thread closed.
 
  • #5
Dennis Plews said:
Both Newton and Einstein, and every one else as far as I am able to discern, assume that gravity works by drawing massive bodies together through space-time warping. I have not yet been able to find any writer who can explain how gravity forces mass and energy to follow geodesic lines.
You won't be able to - that answer does not exist. We could try explaining why mass follows geodesics in spacetime by saying it's just a restatement of Newton's first law, but that just leads the next "why?" question: Why does Newton's first law work? The only answer to that question is "Because that's the way the universe we live in works". Physics is about knowing what laws govern the behavior of the universe, not why the universe behaves according to those laws.

The forum rules do not allow discussion of personal theories and speculation, so this thread is closed.
 
  • #6
Nugatory said:
You won't be able to - that answer does not exist.

To be clear: the question you're responding to is "why"; but the OP asked "how". GR does explain how the trajectories of objects are determined. It just doesn't explain why (because, as you note, physics doesn't answer those kinds of "why" questions).
 

Related to Gravity & Dark Energy: Newton, Einstein & Beyond

1. What is gravity?

Gravity is the force that attracts objects with mass towards each other. It is responsible for keeping planets in orbit around the sun and for keeping objects on Earth's surface.

2. How did Newton contribute to our understanding of gravity?

Isaac Newton's theory of gravity, known as the law of universal gravitation, states that every object in the universe is attracted to every other object with a force that is directly proportional to their masses and inversely proportional to the square of the distance between them.

3. What is Einstein's theory of general relativity?

Einstein's theory of general relativity explains gravity as the curvature of spacetime caused by the presence of mass and energy. This theory has been proven to be more accurate than Newton's theory in extreme conditions, such as near massive objects or at high speeds.

4. What is dark energy?

Dark energy is a hypothetical form of energy that is believed to make up about 68% of the universe. It is thought to be responsible for the accelerated expansion of the universe and its exact nature is still unknown.

5. How are gravity and dark energy related?

Gravity and dark energy are both fundamental forces that affect the behavior of the universe. While gravity is responsible for the attraction between objects with mass, dark energy is believed to be the force driving the expansion of the universe. However, the exact relationship between these two forces is still not fully understood.

Similar threads

  • Special and General Relativity
Replies
7
Views
1K
  • Special and General Relativity
Replies
6
Views
1K
Replies
1
Views
348
  • Special and General Relativity
Replies
9
Views
1K
  • Special and General Relativity
Replies
1
Views
1K
  • Special and General Relativity
Replies
29
Views
3K
  • Special and General Relativity
Replies
4
Views
1K
  • Special and General Relativity
Replies
18
Views
1K
  • Special and General Relativity
Replies
6
Views
2K
  • Special and General Relativity
Replies
2
Views
886
Back
Top