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Vincent Neave
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We are told that space is expanding and that the rate of expansion is speeding up. However, as relativity shows that space and time are inextricably linked, does this mean that time is expanding too?
Vincent Neave said:However, as relativity shows that space and time are inextricably linked, does this mean that time is expanding too?
Vincent Neave said:We are told that space is expanding
Vincent Neave said:relativity shows that space and time are inextricably linked
Vincent Neave said:does this mean that time is expanding too?
Vincent Neave said:this article is interesting and bears on my question
karthik kamath said:If the universe stops expanding, will time come to a standstill?
Niwrad said:1. If you pay very special attention you will discern that there is no definition for space.
Niwrad said:No one can give you a non mathematical definition of space.
Niwrad said:2. Still if space came to a standstill there would still be a time between points.
Niwrad said:Space/time will prove to be the Bandersnach (no good) of Physics.
Based on my understanding of the relativity of simultaneity, I believe time has elapsed the same at all points in the universe, and will continue to do so unless expansion somehow reverses course and compresses at a higher rate.Vincent Neave said:We are told that space is expanding and that the rate of expansion is speeding up. However, as relativity shows that space and time are inextricably linked, does this mean that time is expanding too?
stoomart said:Based on my understanding of the relativity of simultaneity, I believe time has elapsed the same at all points in the universe
My logic comes from the Minkowski diagram in the link and my understanding of the special principle of relativity:PeterDonis said:What is your logic here?
stoomart said:My logic comes from the Minkowski diagram in the link and my understanding of the special principle of relativity
That was my initial assumption from intuition, which comes from another assumption that there are infinite inertial frames or points in the universe.PeterDonis said:How does this get you to "time has elapsed the same at all points in the universe"?
stoomart said:That was my initial assumption from intuition
stoomart said:which comes from another assumption that there are infinite inertial frames or points in the universe
No argument here, just stating my opinion based on my understanding of this stuff.PeterDonis said:But then it isn't a logical argument based on anything, let alone the Minkowski diagram and SR.
My understanding comes from the concept of absolute time described by Newton:I don't understand how this gets you to "time has elapsed the same at all points in the universe" either. Coordinate time is different in each frame; it's not the same in all frames. And in any case, spacetime in our actual universe is curved, so there are no global inertial frames, only local ones.
stoomart said:My understanding comes from the concept of absolute time
Khashishi said:What does it mean for time to be expanding? For time to be bigger at later times makes no sense.
stoomart said:That was my initial assumption from intuition, which comes from another assumption that there are infinite inertial frames or points in the universe.
My understanding is relativity and all its complexities is only necessary for an observer to accurately perform measurements; but like the tree falling in the woods thought experiment, the absence of observation does not negate the existence of an absolute time/simultaneity, it just makes it of little practical value to science.PeterDonis said:Sorry, absolute time isn't a valid concept in relativity. We're talking about relativity here, not Newtonian physics.
stoomart said:My understanding is relativity and all its complexities is only necessary for an observer to accurately perform measurements
stoomart said:the absence of observation does not negate the existence of an absolute time/simultaneity, it just makes it of little practical value to science
stoomart said:I think we could agree that at any given moment, any two CMB radiation waves that decoupled simultaneously have existed for exactly the same duration, regardless of their energy level or traveled path.
I wasn't aware we had direct observations of time dilation, which I agree does seem damning for the idea of absolute time/simultaneity. Going back to your post #3, is it accurate to say expansion affects the passage of time for any observer relative to another across the universe?PeterDonis said:We don't just have an "absence of observation" of absolute time. We have direct observations that contradict absolute time. If absolute time were correct, "twin paradox" type observations would be impossible, but we have such direct observations.
stoomart said:I wasn't aware we had direct observations of time dilation, which I agree does seem damning for the idea of absolute time/simultaneity.
Thanks Drakkith, the Hafele and Keating experiment was the most understandable and convincing to me.Drakkith said:Here are a few experimental tests. All of them agree with SR/GR.
http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html#Tests_of_time_dilation
stoomart said:I wasn't aware we had direct observations of time dilation
stoomart said:is it accurate to say expansion affects the passage of time for any observer relative to another across the universe?
The expansion of space and time refers to the continuous increase in the size and duration of the universe. This concept is based on the theory of the Big Bang, which proposes that the universe began as a singularity and has been expanding ever since.
Scientists have observed the expansion of space and time through various methods, such as measuring the redshift of distant galaxies and observing the cosmic microwave background radiation. These observations provide evidence that the universe is expanding and that space and time are expanding along with it.
The exact cause of the expansion of space and time is still a topic of ongoing research and debate among scientists. However, the most widely accepted explanation is the theory of dark energy, which suggests that there is a mysterious force pushing the universe apart at an accelerating rate.
Based on current scientific understanding, it is unlikely that the expansion of space and time will ever stop. In fact, it is believed that the expansion may continue indefinitely, leading to a "heat death" of the universe where all matter and energy are spread out and the universe reaches a state of maximum entropy.
The expansion of space and time has very little impact on our daily lives because the expansion happens at a scale that is much larger than what we can perceive. However, it has significant implications for the future of the universe and the ultimate fate of our planet and all life within it.