# B Is time a true variable in the scheme of things?

#### Suppaman

Summary
We can affect the passage of time by motion or gravity, does this make it just a parameter affected by "things" in the universe? We can make it go faster?
I accept that time can pass at different rates depending on if the applied motion or gravity (both a parameter in some formula) and as a result time passes at a different rate. However, this seems to imply that we have some control over how slow time may pass. So, if that is just a fact of the physical universe, please let us develop a means of speeding up time. The math problems that would take the age of the universe to calculate could be done in a blink of the eye if the appropriate values of attributes were applied to whatever controls the passage of time for an object such as a computer. Since slowing time down does not seem to violate any of the fundamental laws of the universe perhaps speeding time up will work? I did some searching on the web and did not find anything about this.

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#### PeroK

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If you did speed up time, I'm not sure how anyone would notice.

#### Suppaman

A clock would record more time.

#### PeroK

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A clock would record more time.
More than what?

If time sped up. Let's say a year passed in a day, whatever that might mean. Then the Earth would orbit the Sun, we'd all physically be a year older, the clocks would have advanced a year and no one would have noticed any difference from a normal year. Everyone would think a year had passed. And, in a way, it would have. Who would know that only a day had passed?

If a year's worth of physical change has taken place, then isn't that by definition a year?

#### Suppaman

When we measure time passing by clocks at a different distance from a gravitational source we notice the difference. If we had a way to change the speed of time for a clock it could record more time than a reference clock.

#### phinds

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@Suppaman, it's not quite clear but I think you may have a fundamental misunderstanding. No matter where you are in a gravity well, or how fast you are going relative to some frame of reference, your time does NOT go faster or slower. It just chugs along at one second per second. I think you are confusing differential aging with time dilation.

#### PeroK

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When we measure time passing by clocks at a different distance from a gravitational source we notice the difference. If we had a way to change the speed of time for a clock it could record more time than a reference clock.
You just tinker with the mechanism. Then it would run fast. But, that wouldn't be any physical difference. If you want to change all clocks, then everything is a clock. Your body chemistry and biology included. So, if "local time" changed you wouldn't notice it, because you would be changing too.

In terms of gravitational time dilation, that is time somewhere else. If you travel on a relativistic space flight and/or hover close to a black hole then return to Earth, then a long time may have passed on Earth. But, the people on Earth didn't think that their lives passed in a second. They would have lived and experienced normal lives.

#### Suppaman

The clock ten feet higher than where I am is experiencing a different rate of time then I am. A clock on a satellite moving at a faster speed than I am is experiencing a different clock time than I do. If I had a means of affecting whatever controls the rate of time in an object it would be useful. Motion and gravity can do it, perhaps there is a way of speeding time up. Is that against any of the laws of physics? We can slow it down, why not speed it up?

#### phinds

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The clock ten feet higher than where I am is experiencing a different rate of time then I am. A clock on a satellite moving at a faster speed than I am is experiencing a different clock time than I do.
Absolutely not correct. You are, as I assumed, confusing differential aging with time dilation. EVERY clock everywhere, at whatever speed, "experiences" exactly the same rate of time. What is confusing you is that clocks can (a) APPEAR different to a non-local observer and (2) take different paths through space-time so that if two of them are synchronized and then moved apart and then back together they can have experienced a different number of ticks (but again, each at one second per second).

#### PeroK

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The clock ten feet higher than where I am is experiencing a different rate of time then I am. A clock on a satellite moving at a faster speed than I am is experiencing a different clock time than I do. If I had a means of affecting whatever controls the rate of time in an object it would be useful. Motion and gravity can do it, perhaps there is a way of speeding time up. Is that against any of the laws of physics? We can slow it down, why not speed it up?
Those differences are so small that they are of no practical value. It's possible of course, if you wanted to preserve something, you could send it off on a relativistic space flight. But, that's not very practical.

There's no way to speed something up significantly relative to us on Earth, for example. That would be really useful. A computer could run a long program in no time. But, there's no way to do that.

If you put it into space, then technically it's runner faster than an equivalent computer on Earth, but the maximum you can gain from this is very small. The Earth's gravity is too weak.

#### phinds

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If you put it into space, then technically it's runner faster than an equivalent computer on Earth
No, it is not. You are making the same mistake as the OP. It is running at one second per second. It LOOKS like it is running faster and if you bring it back to Earth it will have ticked a different number of times, but it will not have done so at a different rate, it will simply have taken a different path through space-time.

#### PeroK

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No, it is not. You are making the same mistake as the OP. It is running at one second per second. It LOOKS like it is running faster and if you bring it back to Earth it will have ticked a different number of times, but it will not have done so at a different rate, it will simply have taken a different path through space-time.
In practical terms it's running faster.

#### phinds

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In practical terms it's running faster.
No, it's not. In practical terms, you have to account for the fact that is moving through space-time on a different path than an Earth-bound clock, but saying that it is running faster is just wrong.

#### PeroK

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No, it's not. In practical terms, you have to account for the fact that is moving through space-time on a different path than an Earth-bound clock, but saying that it is running faster is just wrong.
If we lived in a universe where gravitational time dilation was significant, then things like computer rooms would be built as high as possible. And, for all practical purposes, they would run faster than computers in the basement.

Okay you could quibble that its time that is running faster, not the computer; and then you could quibble that time is inherently running at the same rate in the attic and the basement, it's just different relative to each other. But, in the end, if one program finishes long before another then it must have run faster - relative to the end user if nothing else!

#### Nugatory

Mentor
The clock ten feet higher than where I am is experiencing a different rate of time then I am. A clock on a satellite moving at a faster speed than I am is experiencing a different clock time than I do. If I had a means of affecting whatever controls the rate of time in an object it would be useful. Motion and gravity can do it, perhaps there is a way of speeding time up. Is that against any of the laws of physics? We can slow it down, why not speed it up?
Careful here.... you are making an assumption that is so natural that you probably are not aware of making an assumption, but that cannot be justified. We have two clocks at different heights and we claim that time is passing more slowly for the lower clock. What exactly are we saying here?
At the same time that the lower clock reads $T$, the upper clock reads $T'$.
Later the lower clock reads $T+\Delta{T}$ and at the same time the upper clock reads $T'+\Delta{T}'$.
$\Delta{T}'\gt\Delta{T}$ so we say that time is passing more slowly for the lower clock.

But look at what we're saying more closely. The claim depends on how we determine $\delta{T}$ and $\delta{T}'$, and that in turn depends on the vital and dangerously slippery phrase "at the same time". What exactly does it mean to say that two things are happening "at the same time" at two different points in space?

You are making the assumption that "happens at the same time" is an absolute property of a pair of events, and when you look more closely at that assumption (by trying to answer the "How exactly?" question above) you will find it harder to justify than you expect. In fact, it cannot be justified at all - it is simply false, as shown by Einstein's classic train thought experiment on the relativity of simultaneity.

#### Suppaman

Not really, the clock keeping time for both are identical and keep time very well. Move one up the hill and it no longer keeps the same time as the lower clock. An often repeated experiment. I do not have to compare events in the clock as to when they happen. The difference is how fast the clock runs.

#### phinds

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Not really, the clock keeping time for both are identical and keep time very well. Move one up the hill and it no longer keeps the same time as the lower clock. An often repeated experiment. I do not have to compare events in the clock as to when they happen. The difference is how fast the clock runs.
Persisting in this incorrect point of view will never make it correct.

Also, it will prevent you from understanding the physics of what is actually happening.

#### Suppaman

Is there a question about the two clocks giving different time depending on their same position on the earth surface but at a different height?

My original question concerned making a clock go faster, not slower.

#### phinds

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Is there a question about the two clocks giving different time depending on their same position on the earth surface but at a different height?

#### Suppaman

I just did, I was not talking about things happening at the same time. Only that the clocks at different heights recorded different elapsed time. No comparison was intended to relate events between the two clocks.

#### PeroK

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Motion and gravity can do it, perhaps there is a way of speeding time up. Is that against any of the laws of physics? We can slow it down, why not speed it up?
Actually, I can give you a better answer. We on Earth are are almost following a natural path through spacetime. The defining property of a "natural path" or "geodescic" is that it maximises the time you experience. There is a more precise definition of what this means, but that should do for now. No other path than recrosses the a geodesic can have a greater elapsed or "proper" time than along a geodesic.

1) If you could move something to a higher gravitational potential, then it would age faster relative to you. But, as we are at a high potential already there is not much to be done.

2) As we are close to a geodesic path then generally any deviation will result in ageing slower. The options for experiencing less time are much more limited. The best you could do is perhaps move to the north pole, where you are essentially in free fall around the Sun. Again, the differential ageing for someone at the pole is negligibly less than for someone at the equator.

The short answer is, therefore, that there is no path through spacetime where you would return to Earth significantly older than someone who stays on Earth. But, there are paths where you would return significantly younger than those who stayed on Earth.

#### russ_watters

Mentor
When we measure time passing by clocks at a different distance from a gravitational source we notice the difference. If we had a way to change the speed of time for a clock it could record more time than a reference clock.
A reference clock where? What would this get us?

I suppose if you want a reference clock to record more time than a second clock you could send the second clock on a high-speed trip to the nearest black hole and back. I'm not sure why we'd want to do that though.
Motion and gravity can do it, perhaps there is a way of speeding time up. Is that against any of the laws of physics? We can slow it down, why not speed it up?
Sure, you just reverse which clock you call the "reference".

#### Suppaman

Let me give an example. Say we had a means of generating some "field" that caused something within that field to experience a different rate of elapsed time. To be able to do in the lab what currently requires a trip in space at a high speed or in a stronger gravitational field. We can not do this but the concept is valid as we know time can be manipulated. This is accepted.

Now, my question is there any way to speed up time for an object? What would that do for us? Well if you could control this locally it would make for faster computers. If a computer had to run for a week now to get a result if the computer was in a room where time was accellerated it might do a weeks calculation in a second rather than a week. The concept of a slower clock for our near light speed trip is accepted.

Is there any physics rule that would prohibit us from finding a way to speed up time? If time can be slowed, why not made faster?

#### PeroK

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Is there any physics rule that would prohibit us from finding a way to speed up time? If time can be slowed, why not made faster?
See post #21.

#### Suppaman

I just did and there was no mention of anything that prohibited it. You talked about a path through spacetime, that is not my question area.

"Is time a true variable in the scheme of things?"

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