Share Your Thoughts: An Idea to Consider

[filegraphy]

This really is just an idea, but I want to hear what you think.

 

[Fredrik]

The solutions of Einstein's equation that describe an expanding universe are the same ones that describe a universe in which matter is distributed homogeneously and isotropically. (FLRW solutions). The universe is only approximately homogeneous and isotropic at scales much larger than galaxies. At smaller scales, spacetime is much better described by other solutions. For example, near the sun, spacetime is approximately a Schwarzschild solution, in which there is no expansion.

Since Einstein's equation isn't linear, we can't just add these solutions to get the correct one, but I think we can expect the most accurate solution that describes spacetime near the sun to be a lot like Schwarzschild and a little bit like FLRW, with a local expansion that's non-zero, but many, many orders of magnitude smaller than the cosmological expansion (what the FLRW solution predicts).

So never mind elementary particles. Even galaxies (which contain hundreds of billions of stars) are too small for expansion to be relevant.

 

[filegraphy]

In that is non-zero that can mean that the objects are expanding. Thanks it is more clear now.

 

[Academic]

But if they are bound then I think the forces just pull the object back together.

 

[sweet springs]

Hi, filegraphy.
Yes, for massless particles e.g. photon. The expansion of universe cause expansion of wave length of photon as Hubble discovered. I am not sure of it for particles with mass.
Regards.

 

[filegraphy]

Is that what red shift is? When the photon wave is stretched out, causing it to have a lower frequency. This causing the waves in the electromagnetic spectrum to be moving towards the red side. Or am I mistaken? Thank you for your help also.