APOD: Four Quasar Images Surround a Galaxy... (2017 Feb 27)

[neufer]

...
(And I had to go and get that darn wine glass all over again.)

And I had to empy mine again.
But the distortions in the light get easier to see the more often I empty the glass -- I think.

The things we must endure for science

[Gregrrr]

Is it possible that different parts of the universe expand at different rates?

[Chris Peterson]

Is it possible that different parts of the universe expand at different rates?

Well, that's a tricky question. The Universe is four-dimensional (spacetime), which is why we essentially see back in time when we view more distant objects. And the evidence is quite strong that the part of the Universe we see far away is expanding at a different rate than what we see nearby. But in just the three spatial dimensions? There is no observational evidence to suggest that different regions are expanding at different rates (except to the extent that expansion is reduced or eliminated by gravity- the spacetime that contains galaxies, for example, isn't expanding because gravity is holding it together). And current theory doesn't suggest different regions will expand at different rates, either.

So is it possible? Yes. Does anything support the hypothesis? No.

[Fred the Cat]

-- is acting like a choppy gravitational lens. A perhaps even odder thing is that by watching these background quasars flicker, you can estimate the expansion rate of the universe.

I don't suppose the universal clock is a Timex rather than a Rolex and the amount time expands depends on your state of mind.

Wait a minute - my watch says La La Land

You must have been lensed into a pocket of alternative time!

Beam me up, Scotty!

Ann

I noticed this in my Quora e-mail box today. It's difficult me to fathom a universe with different time zones but there are areas where gravity fluctuates immensely.

[sallyseaver]

Thank you Ann, Bruce, Neufer, and Chris for all the good discussion and information about lensing, the Hubble constant and dark matter. I know that it takes time, and you may not realize the value of your contributions live on for many people...even after the day of the APOD image.

Sincerely,
Sally