Universal constants and time dilation

borgie
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Universal constants and time dilation

Universal constants are supposed to be unchanging. But when time dilation occur (during acceleration or increased gravity) doesn't that change all universal constants for that time reference? If it doesn't, an object in time dilation would break apart because of inconsistencies in its constants; i.e. time is going slower but the other constants have not adjusted accordingly.


 

 


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 The word "constant"

 The word "constant" already implies that they're time-invariant.


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 In a word, no.  You are

 In a word, no.

 

You are asking about special relativity here. I would suggest that you read the original paper “On the Electrodynamics of Moving Bodies” by Einstein.

 

http://www.fourmilab.ch/etexts/einstein/specrel/www/

 

Anyway, what is important to note in this context is that time dilation is a phenomenon which only occurs when you consider measurements taken from two different inertial reference frames. The universal constants as measured from any single reference frame will never change.

 

As an example, let's say that you are is a spaceship traveling at nearly the speed of light. Then you switch on your headlights. Why a spaceship needs headlights is beyond me but we will pretend that it does.

 

Now, as it happens, you have a device with you for measuring the speed of light. When you check what is coming out of your headlights, you will find that it is moving ahead of you at 299,792,458 metres per second.

 

But if you are traveling at 299,700,000 meters per second, how is this possible? Surely there is no headroom for even faster speed?

 

Well, the problem here is that you only did some of the math. You need to do all of the math to get a correct answer.

 

Let's say that your spaceship starts parked in orbit around the earth. You can measure your ship and find out that is is 300 meters long. Some dude with a really good telescope can be in Hawaii and measure your spaceship. He will also find it to be 300 meters long.

 

Now you start the ship up and whip off to Pluto, turn around and whip past the Earth at nearly light speed. Here is where you see what matters. You will once again measure your ship and it will be 300 meters long. However, the guy in Hawaii will see your ship and he will measure it as less than a millimeter in length.

 

You see, you forgot to apply the Lorentz transformation.

 

The fact is that at any speed, the Lorentz transformation means that your ship will appear to an outside observer and shortened by exactly the right amount to make the speed of light equal to the speed of light.

 

All other physical constants will be similarly affected, well, apart from the ones which are not even relevant, such as the charge on an electron. The mass of an electron is affected by your speed though and in exactly the way that the Lorentz transformation says it will be.

 

This has been confirmed by experiments in the particle colliders that we use for various physics experiments.

 

And interesting note here is that the newest collider in the LHC in Europe. In it's first month of operation and well before it was even operating at current power levels, one of the first tests that they did was to recreate the whole of known particle physics. You see, by doing that, they could check to see if there was any new thing that caused some variation in the results. Which is kind of important with new huge physics toys.

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borgie wrote:Universal

borgie wrote:

Universal constants are supposed to be unchanging. But when time dilation occur (during acceleration or increased gravity) doesn't that change all universal constants for that time reference?

No. To say that it is a universal constant is to say that it is time invariant.

borgie wrote:
If it doesn't, an object in time dilation would break apart because of inconsistencies in its constants; i.e. time is going slower but the other constants have not adjusted accordingly.

Objects do not go "in" time dilation. Special relativity is a matter of perspective. Velocity is a matter of perspective.

Time in a reference frame different from your own goes slower. You can never observe your own reference frame slowing down. Universal constant do not "adjust." That is why they're called universal constants.

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Constants of nature

Thanks for your response. I'm well aware of what you and butterbattle have said. Either I didn't explain it right or you're missing my point.

Time slowing down is not just a matter of "perspective." I'm sure you're aware of the experiment done with atomic clocks on planes going around earth and one clock left on the ground.

When the planes landed, their clocks were slower than the one on the ground by precisely the amounts predicted by Einstein. In other words, time actually slowed down for the clocks on the plane -- it didn't just "look like it" from the perspective of someone on earth. The clocks on the planes actually slowed down.

My question, then, is -- when time slowed down on the plane, did all of nature's constants change (in the planes, at that moment when time slowed down) accordingly? They must've.

 


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borgie wrote:Thanks for your

borgie wrote:

Thanks for your response. I'm well aware of what you and butterbattle have said. Either I didn't explain it right or you're missing my point.

Time slowing down is not just a matter of "perspective." I'm sure you're aware of the experiment done with atomic clocks on planes going around earth and one clock left on the ground.

When the planes landed, their clocks were slower than the one on the ground by precisely the amounts predicted by Einstein. In other words, time actually slowed down for the clocks on the plane -- it didn't just "look like it" from the perspective of someone on earth. The clocks on the planes actually slowed down.

My question, then, is -- when time slowed down on the plane, did all of nature's constants change (in the planes, at that moment when time slowed down) accordingly? They must've.
 

Time slowing down due purely to relative velocity is purely a matter of perspective, in accordance with  Special Relativity. And ironically, in view of your OP, the apparent changes in Time and Length were calculated precisely to preserve one of those very important constants, the measured velocity of light in a vacuum.

The measured changes in time you describe are a consequence of gravity and acceleration, as per General Relativity, and are indeed 'real' as you describe.

No fundamental constants changed, such as electronic charge, just the rate at which time passed, as measured by regular events such as clock ticks or atomic vibration.

Did you have any particular constants in mind, which you think might appear to change under such circumstances?

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constants

No constant in particular. I'm referring to all constants; they all must change. Time can't go slower or faster with no other constants being involved.


 


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borgie wrote:Please

I know that stuff, and said as much. That is mainly a consequence of the effects of gravity and acceleration - constant acceleration is equivalent to a uniform gravitational field.

Net Special Relativistic time effects cannot apply to a clock brought back to the same frame of reference at which it started, otherwise we would have a paradox. And you cannot leave a location and return without experiencing acceleration. I think there are further mathematical subtleties in terms of changing of inertial frames of reference.

SR effects do apply to a clock in orbit, or in flight, while it is still in motion relative to the observer, of course, as well as the any gravitational and velocity change GR effects.

You haven't mentioned what constants you think might be affected.

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Just in case you don't get

Just in case you don't get it, borgie, you have things backwards.

Time Dilation is not so much a discovered effect that might change the values of Universal Constants, it was proposed by Einstein, in combination with length contraction, as NECESSARY to make one of the most important of those constants, namely the speed of light in a vacuum, really constant for observers in all inertial frames of reference, regardless of their relative motion. That constancy had been measured by the Michelson-Morley experiment.

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BobSpence1 wrote:Net Special

BobSpence1 wrote:

Net Special Relativistic time effects cannot apply to a clock brought back to the same frame of reference at which it started, otherwise we would have a paradox.

 


I don't get how you can say this.

Here's a quote from http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/airtim.html#c2 (an exeperiment quoted in many places):

"In 1971, experimenters from the U.S. Naval Observatory undertook an experiment to test time dilation . They made airline flights around the world in both directions, each circuit taking about three days. They carried with them four cesium beam atomic clocks. When they RETURNED and compared their clocks with the clock of the Observatory in Washington, D.C., they had gained about 0.15 microseconds compared to the ground based clock."

Again, I'm not talking about any particluar constant. I'm refrring to all constants.
 


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borgie wrote:BobSpence1

borgie wrote:

BobSpence1 wrote:

Net Special Relativistic time effects cannot apply to a clock brought back to the same frame of reference at which it started, otherwise we would have a paradox.

 


I don't get how you can say this.

Here's a quote from http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/airtim.html#c2 (an exeperiment quoted in many places):

"In 1971, experimenters from the U.S. Naval Observatory undertook an experiment to test time dilation . They made airline flights around the world in both directions, each circuit taking about three days. They carried with them four cesium beam atomic clocks. When they RETURNED and compared their clocks with the clock of the Observatory in Washington, D.C., they had gained about 0.15 microseconds compared to the ground based clock."

Again, I'm not talking about any particluar constant. I'm refrring to all constants.
 

That experimental result was due to gravitational effects of General Relativity, not the pure effects of Special Relativity which is what I was referring to.

Ok, if you are concentrating on the way higher gravitational fields cause clocks to run slower, as well as all other physical processes, that is also related, in a more complex way than with Special Relativity, to maintaining the speed of light constant. So that is one of the fundamental constants that explicitly does not change under those conditions.

As to other constants, why would you expect the charge on the electron to change in high gravity/time dilation?

Or the gravitational constant defining the value of the force of gravitational attraction between two masses at a specified distance apart?

Or the force of attraction between magnets?

Or the rest mass of fundamental particles?

And so on...

Those are a selection of fundamental, universal constants. Most of them are like that.

Why would they be necessarily affected by Gravitational Time Dilation?

The universal constants are normally measured by the ration between two observed quantities. If one is affected by Time Dilation, what happens is that the other is also affected to the same degree, either directly by the gravitational field, or by some other factor that does change as part of the same scenario, so the ratio does not change. That is what happens when we observe something moving at a steady velocity relative to ourselves - the combination of Time Dilation and Lorentz Contraction mean that we all still measure the speed of the same beam of light as the same, regardless of what speed we are traveling at.

That is the basic reason why real universal constants do not change due to Time Dilation effects.

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time dilation

My issue is not necessarily with how time slows down or speeds up, but the fact that it does. When the clocks return to earth and are compared to the clock on earth, there is a difference in time. Whether it was the speed or the gravity is immaterial. The point that I'm making is that in the period when the clocks flying in the planes speed up (whenever it is that that happens), it's inconceivable that no other constant was affected by that speeding up of time. For example, the atomic activity would have to speed up too. Granted, when the planes land back on earth their clocks are again in sync with our time reference. But when they're still in the air and time their is running faster, other constants have to also be running at a faster speed.

In other words, if electrons are spinning at their normal rate of X per second, and time speeds up, then the electrons would have to spin faster. Yes, they'd still be spinning at the rate of X per second within that time reference. But since that time reference is moving at a faster clock-speed then everything in that time reference, including their subatomic components, would have to pick up speed to be consistent with that higher-speed time reference. That's all I'm saying.

 


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borgie wrote:My issue is not

borgie wrote:

My issue is not necessarily with how time slows down or speeds up, but the fact that it does. When the clocks return to earth and are compared to the clock on earth, there is a difference in time. Whether it was the speed or the gravity is immaterial. The point that I'm making is that in the period when the clocks flying in the planes speed up (whenever it is that that happens), it's inconceivable that no other constant was affected by that speeding up of time. For example, the atomic activity would have to speed up too. Granted, when the planes land back on earth their clocks are again in sync with our time reference. But when they're still in the air and time their is running faster, other constants have to also be running at a faster speed.

In other words, if electrons are spinning at their normal rate of X per second, and time speeds up, then the electrons would have to spin faster. Yes, they'd still be spinning at the rate of X per second within that time reference. But since that time reference is moving at a faster clock-speed then everything in that time reference, including their subatomic components, would have to pick up speed to be consistent with that higher-speed time reference. That's all I'm saying.
 

But those things you refer to are not Universal Constants. The natural frequencies of electrons do change, that is an event in the same class as a ticking clock, like other vibrations of particles. It is actually used to make highly accurate clocks. We use the change in the frequency of light emitted by electrons as a measure of the gravitational field they are in.

So yes, everything vibrating in someway analogous to a pendulum, a spring and balance wheel, a quartz crystal, a tuning fork, the rates at which chemical reactions proceed, will all slow down to the same extent. The amount of change will itself be determined by calculations employing some actual universal constants.

OTOH, the rate of radioactive decay appears to be independent of gravitational field, which I will admit I don't quite understand, although it gets into quantum effects, which haven't been fully reconciled with Relativity.

BTW, there are no cases I am aware of where time speeds up compared to what it is in the absence of gravity or in an inertial frame of reference.

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I think we're on the same

I think we're on the same page now.

I wasn't aware of "the rate of radioactive decay appears to be independent of gravitational field". I'll have to read up on that.

Thanks for your input.

 


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borgie wrote:Universal

borgie wrote:

Universal constants are supposed to be unchanging. But when time dilation occur (during acceleration or increased gravity) doesn't that change all universal constants for that time reference? If it doesn't, an object in time dilation would break apart because of inconsistencies in its constants; i.e. time is going slower but the other constants have not adjusted accordingly.

What about the relative nature of time changes constants not contingent upon time? I think you're going in circles here...

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Google "Lorentz

Google "Lorentz Invariance."

 

There's a heck of a lot of stuff in physics which is Lorentz Invarient.  This means that a Lorentz Transformation (which is the mathematical representation of what happens when you go into a different inertial reference frames) leaves it unchanged.  Things like this include the speed of light, but also the dot-product between the E and B fields in electromagnetism (as well as the difference of the squares of their magnitude).  Other things like proper time are defined in a particular problem-dependent reference frame (generally the "proper" attribute is the one measured in a co-moving frame, or a frame in which the matter in question appears at rest).

 

In short, relativistic physics is built on things that don't change when you go hopping from reference frame to reference frame.

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Zaq wrote:Google "Lorentz

Zaq wrote:

Google "Lorentz Invariance."

 

There's a heck of a lot of stuff in physics which is Lorentz Invarient.  This means that a Lorentz Transformation (which is the mathematical representation of what happens when you go into a different inertial reference frames) leaves it unchanged.  Things like this include the speed of light, but also the dot-product between the E and B fields in electromagnetism (as well as the difference of the squares of their magnitude).  Other things like proper time are defined in a particular problem-dependent reference frame (generally the "proper" attribute is the one measured in a co-moving frame, or a frame in which the matter in question appears at rest).

 

In short, relativistic physics is built on things that don't change when you go hopping from reference frame to reference frame.

 

THanks, but yoi miss the point. The very fact that everything looks "normal" in every reference frame, yet time does go at different speeds, that means everything else, all constans of naure, eyc., change in the same proportion as time.

 


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No offense, but I don't

No offense, but I don't think I'm the one missing the point.

 

The speed of light does not change when you change reference frames.

The scalar product between E and B does not change when you change reference frames.

The proper time between two events does not change when you change reference frames.

The categories of spacelike, timelike, and lightlike curves are identical in all reference frames.

Plank's constant is the same in all reference frames.

Etc.

 

The point is that relativistic physics is built on these typse of things.  Things that change from reference frame to reference frame do not form the foundations of relativistic physics.  These things may be treated as constant when velocities are much smaller than the speed of light, in order to simplify the problem.  But physicists recognize that doing this is a (often highly accurate) approximation.

Correct me if I'm wrong, but you seem to be asking how physics still "works" when the constants change.  The answer is that the constants we build the theory on don't change.  There is enough frame-independent stuff that we can build a coherent physics that works in all reference frames.

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"...you seem to be asking

"...you seem to be asking how physics still 'works' when the constants change..."

No, this is not what I'm asking. But your assumption actually verifies what I'm driving at. For reasons I can't explain here, I'm trying to verify that physics does in fact work in any reference frame although the constants have changed.
 


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borgi wrote:"...you seem to

borgi wrote:

"...you seem to be asking how physics still 'works' when the constants change..."

No, this is not what I'm asking. But your assumption actually verifies what I'm driving at. For reasons I can't explain here, I'm trying to verify that physics does in fact work in any reference frame although the constants have changed.

And you're verified this because of what someone just wrote on an online forum?

 

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You have a point there. My

You have a point there. My logic is that if enough people come to the same conclusion I came to, there may (not necessarily, though) be some truth to it.

 


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borgi wrote:I'm trying to

borgi wrote:

I'm trying to verify that physics does in fact work in any reference frame although the constants have changed. 
 

 

Then the answer's the same.  The constants don't change.  Yeah, some things we thought were constants change, but there are plenty of things that really are constant regardless of reference frame that physics isn't fazed.  Once you hit relativistic speeds, you use relativistic theories, and the only things those theories treat as constant are the things that don't vary between reference frames.  Things like c and hbar and 4-vector dot products.

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