"Quasar clocks" and time running slower long ago

[hkyriazi]

Regarding the new "quasar clock" data showing that time ran more slowly (~5-fold) shortly after the Big Bang: is it all based on the periodic variation in luminosity at various wavelengths of some quasars (and presumably explained by the special relativistic time dilation effect from "spatial expansion")?

 

[berkeman]

Regarding the new "quasar clock" data showing that time ran more slowly (~5-fold) shortly after the Big Bang: is it all based on the periodic variation in luminosity at various wavelengths of some quasars (and presumably explained by the special relativistic time dilation effect from "spatial expansion")?

Please always post links to your references when starting a new thread in the technical forums. Thank you.

 

[Vanadium 50]

What does it even mean for a clock to run slower in the past? How do you compare them?

 

[hkyriazi]

What does it even mean for a clock to run slower in the past? How do you compare them?

I assume the researchers noticed that quasars of a certain type (which have luminosity variations of a certain period) have their luminosity vary 5-fold slower than quasars much closer to us.

 

[hkyriazi]

Please always post links to your references when starting a new thread in the technical forums. Thank you.

Here's a link to a description of the new findings:
https://scitechdaily.com/einstein-v...iverse-was-5x-slower-soon-after-the-big-bang/

 

[PeterDonis]

I assume the researchers noticed that quasars of a certain type (which have luminosity variations of a certain period) have their luminosity vary 5-fold slower than quasars much closer to us.

Yes. And this is exactly what is expected for objects at that redshift. It does not mean time was actually "running slower" back then. It is, as you propose in your OP, the same kind of time dilation as we would see in SR for objects with the same redshift.

 

[Vanadium 50]

Again I ask, "What does it even mean for a clock to run slower in the past? How do you compare them?"

I know how to say two sticks are the same length - put them next to each other and compare where their endpoints are. But what does it mean to say that a second ten years ago is shorter or longer than a second today?

I don't know what paper the Science News authors read, but it sure doesn't sound like the one they referenced. What the paper claims is that quasar variability matches what you expect from redshifts.

 

[PeterDonis]

I don't know what paper the Science News authors read, but it sure doesn't sound like the one they referenced.

Unfortunately this is typical of such articles, even in Science News, where the writers should know better.

 

[Bandersnatch]

Come on, guys. It hasn't even been two months since the last thread on this. You were both there:
https://www.physicsforums.com/threads/cosmological-time-dilation-of-high-redshift-quasars.1053780/

Again I ask, "What does it even mean for a clock to run slower in the past? How do you compare them?"

You use standard candles, if available. Kinda hard to do with quasars unambiguously, but the authors make an effort.

It's Lewis, Brewer; 2023 btw. Link in the other thread.

 

[PeterDonis]

It hasn't even been two months since the last thread on this.

Yes, fair point. And given that that thread and this one both give sufficient responses to the OP's question, this thread is now closed.