Was the flow of time slower in the early universe?

In summary, the question of whether extra gravity in the early universe caused time to run slower is better suited for the relativity forum, as time dilation is relative to the observer. Multiple links are provided that discuss observed time dilation and the use of comoving time in the FLRW metric to measure the history of the universe. The consensus is that the early universe was more dense and time may have run slower for the average observer, but the effect would be undetectable. The density of the universe during the Plank and GUT epochs may have been high enough for time dilation, but it is uncertain and not enough for an external observer to see. The creation of cosmic background radiation would not have affected time dilation due to the gravitational potential of
  • #1
jalak7
7
0
When the universe was young, and everything was closer together, did the extra gravity cause time to run slower than it does now?
 
Space news on Phys.org
  • #2
This question is better suited in the relativity forum. Your going to need to define from which observer? Time dilation is relative to the observer. This link is from our observer perspective.

http://www.newscientist.com/article/dn13792-cosmic-time-warp-revealed-in-slowmotion-supernovae.html

here is another link that has several links to observed time dilation

http://www.astro.ucla.edu/~wright/cosmology_faq.html#TD

When you see the history of the universe plotted against time, the time used is the comoving time i.e. the time measured by a clock that is at rest with respect to the universe around it. This is the time co-ordinate used in the FLRW metric, which is a solution to the equations of GR that, as far as we can tell, gives a good description of the universe back to very early times.
 
Last edited:
  • Like
Likes Thelamon
  • #3
Quite logically from what we know the simple answer would be yes.And considering that the early universe was much more dense , in fact a lot more dense I would say that time run slower for every average observer no matter where one would be in the early universe.
As it expanded it became more and more like the universe we know today with planets and black holes with huge mass and hence gravity around them and then with a lot of "empty" space between with quite small gravitational potential.
 
  • #4
If all clocks run more slowly what effect would that have? It would be undetectable. Gravitational redshift is vanishingly small unless you are very near a compact object. The universe is not a compact object.
 
  • #5
Crazymechanic said:
Quite logically from what we know the simple answer would be yes.And considering that the early universe was much more dense , in fact a lot more dense I would say that time run slower for every average observer no matter where one would be in the early universe.
It seems you are talking about 'proper' time, the time your wristwatch is showing. By no means can you tell that the time it shows runs slower.
In contrast, if you watch a Galaxy in the early universe, then its redshift is due to cosmic time dilatation caused by the expansion of the universe. But then we talk about coordinate time.
 
  • #6
Crazymechanic said:
Quite logically from what we know the simple answer would be yes.And considering that the early universe was much more dense , in fact a lot more dense I would say that time run slower for every average observer no matter where one would be in the early universe.
As it expanded it became more and more like the universe we know today with planets and black holes with huge mass and hence gravity around them and then with a lot of "empty" space between with quite small gravitational potential.

The only era in the past that might (key word might) be dense enough to dilate time would be prior to the inflationary era. We would never be able to see this far back. Due to the shroud of
darkness. Here is one of the furthest objects we can see and why.

http://www.newscientist.com/mobile/article/dn22611-hubble-sees-earliest-known-galaxies-through-cosmic-fog.html
 
  • #7
Mordred said:
The only era in the past that might (key word might) be dense enough to dilate time would be prior to the inflationary era.
I'm not sure there's actually any time dilation at all from the average matter density.
 
  • #8
To be honest with you neither am I. Granted I also cannot find any reliable source with an estimate of the density of the Planch and GUT epoch. Some of the older particle physics articles covering the TOE aspects of these epochs. Place the density around 10^78 gm/cm^3. The article is reliable in regards to particle physics. If one accepts TOE. However its calculations are based on a far older inflationary model. Still doubt that would be enough for time dilation. Assuming we have a magic telescope to allow us to be an outside observer lol.
 
  • #9
Mordred said:
To be honest with you neither am I. Granted I also cannot find any reliable source with an estimate of the density of the Planch and GUT epoch. Some of the older particle physics articles covering the TOE aspects of these epochs. Place the density around 10^78 gm/cm^3. The article is reliable in regards to particle physics. If one accepts TOE. However its calculations are based on a far older inflationary model. Still doubt that would be enough for time dilation. Assuming we have a magic telescope to allow us to be an outside observer lol.
I'm pretty sure this can be solved by comparing the time coordinate in FRW to proper time. For an observer stationary with respect to the background, those two are the same thing. So yes, there is no time dilation from the expansion.
 
  • #10
I agree on that, considering that was one of the higher estimates in any non pop/mass media article I've come across. I've got a huge collection of them as I'm currently self studying early particle physics.
 
  • #11
When cosmic background radiation was created the time flow throughout the universe was pretty much the same everywhere, right? So if we made a clock based on that and called it a universal clock, then would the flow of time in the early universe be slower relative to the universal clock than time flow is today, because of the difference in gravity?
 
  • #12
No the gravitational density isn't sufficient to dilate time. Gravitational density time dilation only occurs around massive bodies or near relativistic velocities.
We would see redshift due to expansion which from our observer would look dilated but not due to to the gravitational potential of the radiation era. Remember time dilation is seen by an external observer, time flows normal for an observer in the massive gravitational well.
 
Last edited:
  • #13
jalak7 said:
When cosmic background radiation was created the time flow throughout the universe was pretty much the same everywhere, right? So if we made a clock based on that and called it a universal clock, then would the flow of time in the early universe be slower relative to the universal clock than time flow is today, because of the difference in gravity?
I think the problem is that there isn't any way to compare relative time dilation between two different points in time.
 
  • #14
Simply put there wouldn't be.

https://www.physicsforums.com/showthread.php?
p=4367783#post4367783

the above thread is similar to this one. Timmdeeg gave a good correlation. One I had completely missed lol.
 
  • #15
I would think that in the early universe time ticked at the same rate for all clocks, coordinate time was the only time. As the duration of the universe increased the difference between coordinate time of the universe and the proper time of matter began to differ as they aged at about the same rate. The simultaneous moment of coordinate time, one clock for the universe, as compared with the simultaneous motion of a single clock within it.
 
  • #16
timmdeeg said:
To my understanding even much higher matter density of the universe in the past wouldn't cause gravitational time dilation, because in contrast to Schwarzschild metric the gravitational potential in the FRW model is isotropic. May be this wording isn't correct. What I mean is that as long as we keep the picture that the redshift is due to expansion the density plays no role.

If a particular De-Sitter (matter removed) time slice has no gravity wells to cause a redshift. That lack of dilation cannot be seen in another time slice. So the only measurable difference in regards to redshift would be due to expansion. Also keep in mind the universal energy-density at any time after the inflationary epoch is not enough to cause a dilation. Not that it matters given the above.
 
  • #17
Mordred said:
If a particular De-Sitter (matter removed) time slice has no gravity wells to cause a redshift. That lack of dilation cannot be seen in another time slice. So the only measurable difference in regards to redshift would be due to expansion. Also keep in mind the universal energy-density at any time after the inflationary epoch is not enough to cause a dilation.
Hi Mordred, the cosmological redshift/time dilation is directly related to the scale factor and to the special relativistic Doppler formula in the empty case, resp. Thus we fortunately don't have to care about things like time slices, energy density and a certain epoch. Indirectly yes, as the dynamics depend on energy density, pressure and lambda.
 
  • #18
petm1 said:
I would think that in the early universe time ticked at the same rate for all clocks, coordinate time was the only time. As the duration of the universe increased the difference between coordinate time of the universe and the proper time of matter began to differ as they aged at about the same rate. The simultaneous moment of coordinate time, one clock for the universe, as compared with the simultaneous motion of a single clock within it.
I think the distinction proper time vs. coordinate time is not related to how in which epoch the universe develops. As soon as there is a distance, there is relativity, means there is proper time, which is invariant and coordinate time, which isn't.
 
  • #19
At some point in the smaller denser hotter past all the makings for all of our clocks were local and ticking at the same rate.
 
  • #20
petm1 said:
At some point in the smaller denser hotter past all the makings for all of our clocks were local and ticking at the same rate.
I am not sure, what you want to say. Perhaps this is of some help. Coordinate/proper time is not related to density.
 
  • #21
Entropy of the universe goes from the order of one simultaneous event, the same for all future clocks, to the disorder of differences between clocks, as viewed via photons, counting their own simultaneous existence.
 

1. What evidence supports the idea that time was slower in the early universe?

The main evidence for the slower flow of time in the early universe comes from the observed cosmic microwave background radiation. This radiation is believed to be the leftover energy from the Big Bang and its pattern closely matches that of a blackbody, indicating a uniform and hot early universe. The fact that the cosmic microwave background has a uniform temperature across the sky also suggests that the universe was expanding and cooling at a consistent rate, which is a key factor in determining the speed of time.

2. How does the theory of relativity contribute to our understanding of time in the early universe?

Albert Einstein's theory of relativity states that time is relative and can be affected by factors such as gravity and velocity. In the early universe, both of these factors were much stronger compared to the present day. This means that time would have passed at a slower rate in the early universe due to the high gravitational forces and the rapid expansion of space.

3. Could time have been completely different in the early universe?

Based on our current understanding of physics, time is an essential component of the universe and cannot be completely different in different regions or eras. However, the rate at which time flows can vary based on the conditions present. Therefore, while time may have been slower in the early universe, it still existed and followed the laws of physics.

4. Is there any way to directly measure the speed of time in the early universe?

Unfortunately, there is no direct way to measure the flow of time in the early universe as we cannot observe it directly. However, by studying the cosmic microwave background and other astrophysical phenomena, scientists can make precise calculations and predictions about the rate of time in the early universe.

5. How does the concept of entropy play a role in understanding the flow of time in the early universe?

Entropy is a measure of disorder and is closely related to the flow of time. In the early universe, the high energy and high temperatures meant that the universe was in a state of low entropy, meaning it was highly ordered. As the universe expanded and cooled, the entropy increased, indicating that time was passing. This concept is known as the second law of thermodynamics and helps us understand the direction of time's flow in the early universe and beyond.

Similar threads

Replies
8
Views
1K
Replies
2
Views
444
  • Cosmology
Replies
8
Views
1K
Replies
5
Views
1K
  • Cosmology
Replies
17
Views
2K
Replies
26
Views
3K
Replies
5
Views
1K
  • Cosmology
Replies
11
Views
1K
Replies
6
Views
2K
  • Cosmology
Replies
1
Views
1K
Back
Top