Light Speed: Fixed... or Relative? Exploring Einstein's Relativity

reply to post by Arbitrageur


I shall continue with the GPS example before I digress.

I am asking you again - what 'theory of relativity' has to do with the difference in clocks?

The 'theory of relativity' is based on two objects moving closer or moving apart, and a third observer.

I can very easily explain the difference in atomic clocks as potential energy is trapped in atomic vibrations. Remember atoms are suspended in space and vibrate due to energy state. So the potential energy of matter affects atomic vibrations which would affect the clock accuracy.

GargIndia
reply to post by Arbitrageur

 

Let us discuss the example of GPS satellite a bit more.

The issue is why the atomic clock in the satellite shows a different time than the clock on earth.

The gravity on surface of the earth has slight variations. Agreed, as it is due to differences in crust material. But how much variation would be in the gravity at the orbit of the satellite? Please remember that the orbit itself naturally adjusts for this gravitational difference. So why would that make a difference to the clock?

Atomic clocks function on a scale of sensitivity. Material, such as clocks, on earth are traveling through space time at a different velocity then clocks in earths orbit. Matter traveling at different speeds 'experience time differently/their energy decays at different rates' so the atomic nature of what makes the clock work is affected differently, and small tiny changes add up over time.

GargIndia
reply to post by Arbitrageur

 

I shall continue with the GPS example before I digress.

I am asking you again - what 'theory of relativity' has to do with the difference in clocks?

The 'theory of relativity' is based on two objects moving closer or moving apart, and a third observer.

In the case of GPS it's mostly a gravitational effect, which is actually quite a bit larger than the opposing motion effect that you're referring to. There is no motion required in general relativity's gravitational effects, but it's related to acceleration of an object in motion by the equivalence principle

A little reflection will show that the law of the equality of the inertial and gravitational mass is equivalent to the assertion that the acceleration imparted to a body by a gravitational field is independent of the nature of the body. For Newton's equation of motion in a gravitational field, written out in full, it is:

(Inertial mass) x (Acceleration) = (Intensity of the gravitational field) x (Gravitational mass).

It is only when there is numerical equality between the inertial and gravitational mass that the acceleration is independent of the nature of the body.

— Albert Einstein

I can very easily explain the difference in atomic clocks as potential energy is trapped in atomic vibrations. Remember atoms are suspended in space and vibrate due to energy state. So the potential energy of matter affects atomic vibrations which would affect the clock accuracy.

So you move the clock in the lab up one meter and it speeds up, you move it down one meter and it slows down....you can explain that? How? It's not inaccurate, it's changing the speed at which it runs based on elevation (and since gravity varies based on elevation...it's a gravitational effect which is by far the largest effect in GPS clock speeds).

ImaFungi

GargIndia
reply to post by Arbitrageur

 

Let us discuss the example of GPS satellite a bit more.

The issue is why the atomic clock in the satellite shows a different time than the clock on earth.

The gravity on surface of the earth has slight variations. Agreed, as it is due to differences in crust material. But how much variation would be in the gravity at the orbit of the satellite? Please remember that the orbit itself naturally adjusts for this gravitational difference. So why would that make a difference to the clock?

Atomic clocks function on a scale of sensitivity. Material, such as clocks, on earth are traveling through space time at a different velocity then clocks in earths orbit. Matter traveling at different speeds 'experience time differently/their energy decays at different rates' so the atomic nature of what makes the clock work is affected differently, and small tiny changes add up over time.

You are making a statement rather than making a proposition, as if you know for sure what is happening. Do you?

Let me make it very clear to you that there is no space-time. There is space and there is time. Time is a virtual parameter which cannot be measured accurately by any means available to humans.

Your statements are highly ambiguous and reflect the confused state of current theoretical Physics.

reply to post by Arbitrageur


The potential energy is due to movement.

I said earlier that every object on earth is moving with the earth. Every object in Universe is moving and thus has a potential energy.

In case of GPS satellite, it is true that kinetic energy given to satellite to place it in orbit is to counter gravity, thus gravity comes into picture (due to equivalence). However for a ship moving in deep space, gravity is not a significant factor. It will still have significant potential energy, due to which atoms will be excited and your atomic clock will give a different time compared to earth.

I am telling you clearly that "theory of relativity" (general or special) has no relation whatsoever with atomic clocks. The relationship exists only in the minds of confused scientists.

"So you move the clock in the lab up one meter and it speeds up, you move it down one meter and it slows down....you can explain that? How? It's not inaccurate, it's changing the speed at which it runs based on elevation (and since gravity varies based on elevation...it's a gravitational effect which is by far the largest effect in GPS clock speeds)."

When you run this kind of experiment, you have to be very careful. You must eliminate all external factors that can affect the clock. For me, your statement is very hard to believe, as it runs counter to the purported accuracy of atomic clocks.

GargIndia
reply to post by Arbitrageur

 

I shall continue with the GPS example before I digress.

I am asking you again - what 'theory of relativity' has to do with the difference in clocks?

The 'theory of relativity' is based on two objects moving closer or moving apart, and a third observer.

I can very easily explain the difference in atomic clocks as potential energy is trapped in atomic vibrations. Remember atoms are suspended in space and vibrate due to energy state. So the potential energy of matter affects atomic vibrations which would affect the clock accuracy.

Ok theres actually two that affects the clock there is gravitational time dilation and spacetime itself. I start with the easier of the two gravitational time dilation. It basically states that the less the gravity there is the faster time itself moves. Notice i didnt say the clock the clock works exactly the same at any gravity level only its frame of reference has changed.Any way this deals with what's called gravitational potential or in relativity metric tensors.Picture each point in space having an energy value the higher the energy value the slower time passes. Einstein didnt see gravity as something that pulls on you but as energy directly related to mass a side effect if you will causing space itself to bend.It simply takes energy to warp space Just like on star trek the more you want to warp space the more energy you need.

Now the hard part in relativity speed also effects your reference frames well more correctly yours doesnt change only how others see them does. This is a cosmic magic trick sort of. Two people moving at different speeds time runs slower for one over the other.Like a satellite circling the earth. I know everyone familiar with the closer you get to the speed of light an outside observer sees you as slowing down. The reason is light itself has a speed limit it can't go faster no matter where or who is observing it.But in order for everything to work time needs to slow down or speed up to make sure light travels at the same speed everywhere. Like a car coming at you down a road at the speed of light you still see the head lights first then youll see the car stream by. Now the person in the car still sees the headlights illuminate the road in front even though the car is moving the same speed as light. But we already said light has to be the same speed regardless of frame of reference so here comes the illusion. Those light beams leaving the car fool the driver not by speeding up but by contracting space which affects the time it takes to travel that distance. Picture two dragsters going the exact same speed but one is on a half mile straight away the other a quater mile. The one with less distance to travel wins. Well when moving at the speed of light you could say it shortens the track or road in my example.

reply to post by dragonridr


Do you yourself understand what you write? Goodluck to you and bad luck to humanity if this is the way PHDs are granted these days.

GargIndia
reply to post by dragonridr

 

Do you yourself understand what you write? Goodluck to you and bad luck to humanity if this is the way PHDs are granted these days.

As i said easier with the math involved trying to make it easy to understand was never one of Einsteins strong points nor mine im afraid you almost have to have some background to relate. By the time students get to tackle these questions they have a background to draw on.

GargIndia
When you run this kind of experiment, you have to be very careful. You must eliminate all external factors that can affect the clock. For me, your statement is very hard to believe, as it runs counter to the purported accuracy of atomic clocks.

I just said "clocks"...I never said they were atomic clocks...you made that assumption. To see the clock speed difference at just one meter of elevation difference, they used a type of clock called an "optical clock". And the difference is pretty small so the accuracy of the clocks is still intact, it's just something you'd never notice with a less accurate atomic clock as it would fall into an error bar. Even the more accurate optical clock has its own error bars, but they are really tiny.

www.scientificamerican.com...

Newly developed optical clocks are so precise that they register the passage of time differently at elevations of just a few dozen centimeters or velocities of a few meters per second...

the effects are minuscule: It would take the elevated clock hundreds of millions of years to log one more second than its counterpart, and a clock moving a few meters per second would need to run about as long to lag one second behind its stationary counterpart. But the development of optical clocks based on aluminum ions, which can keep time to within one second in roughly 3.7 billion years, allows researchers to expose those diminutive relativistic effects. "People usually think of it as negligible, but for us it is not," says lead study author James Chin-wen Chou, a postdoctoral research associate at NIST. "We can definitely see it."

They published their research so you can review it to see if they were careful or not.

Optical Clocks and Relativity

Observers in relative motion or at different gravitational potentials measure disparate clock rates. These predictions of relativity have previously been observed with atomic clocks at high velocities and with large changes in elevation. We observed time dilation from relative speeds of less than 10 meters per second by comparing two optical atomic clocks connected by a 75-meter length of optical fiber. We can now also detect time dilation due to a change in height near Earth’s surface of less than 1 meter. This technique may be extended to the field of geodesy, with applications in geophysics and hydrology as well as in space-based tests of fundamental physics.

So you might want to review that and then see if you can explain it without relativity. That would be interesting.

GargIndia

ImaFungi

GargIndia
reply to post by Arbitrageur

 

Let us discuss the example of GPS satellite a bit more.

The issue is why the atomic clock in the satellite shows a different time than the clock on earth.

The gravity on surface of the earth has slight variations. Agreed, as it is due to differences in crust material. But how much variation would be in the gravity at the orbit of the satellite? Please remember that the orbit itself naturally adjusts for this gravitational difference. So why would that make a difference to the clock?

Atomic clocks function on a scale of sensitivity. Material, such as clocks, on earth are traveling through space time at a different velocity then clocks in earths orbit. Matter traveling at different speeds 'experience time differently/their energy decays at different rates' so the atomic nature of what makes the clock work is affected differently, and small tiny changes add up over time.

You are making a statement rather than making a proposition, as if you know for sure what is happening. Do you?

Let me make it very clear to you that there is no space-time. There is space and there is time. Time is a virtual parameter which cannot be measured accurately by any means available to humans.

Your statements are highly ambiguous and reflect the confused state of current theoretical Physics.

By space time I meant Gravity field, and I meant to imply with the term space time, that the affects seen on the clocks are due to the affects of the clocks traveling different distances of space, in different rates of time, or at different velocities, therefore the materials the clocks are made of are affected ever so slightly. Time is the transformation of energy, comparing our different measurements of time is comparing the different rates at which systems of energy change (for example rates of decay of a cesium atom in atomic clocks, or the earth revolving around the sun, or the earth rotating around its axis).

Skip to 6:16 ... It is worth checking out imo.

Arbitrageur

GargIndia
When you run this kind of experiment, you have to be very careful. You must eliminate all external factors that can affect the clock. For me, your statement is very hard to believe, as it runs counter to the purported accuracy of atomic clocks.

I just said "clocks"...I never said they were atomic clocks...you made that assumption. To see the clock speed difference at just one meter of elevation difference, they used a type of clock called an "optical clock". And the difference is pretty small so the accuracy of the clocks is still intact, it's just something you'd never notice with a less accurate atomic clock as it would fall into an error bar. Even the more accurate optical clock has its own error bars, but they are really tiny.

www.scientificamerican.com...

Newly developed optical clocks are so precise that they register the passage of time differently at elevations of just a few dozen centimeters or velocities of a few meters per second...

the effects are minuscule: It would take the elevated clock hundreds of millions of years to log one more second than its counterpart, and a clock moving a few meters per second would need to run about as long to lag one second behind its stationary counterpart. But the development of optical clocks based on aluminum ions, which can keep time to within one second in roughly 3.7 billion years, allows researchers to expose those diminutive relativistic effects. "People usually think of it as negligible, but for us it is not," says lead study author James Chin-wen Chou, a postdoctoral research associate at NIST. "We can definitely see it."

They published their research so you can review it to see if they were careful or not.

Optical Clocks and Relativity

Observers in relative motion or at different gravitational potentials measure disparate clock rates. These predictions of relativity have previously been observed with atomic clocks at high velocities and with large changes in elevation. We observed time dilation from relative speeds of less than 10 meters per second by comparing two optical atomic clocks connected by a 75-meter length of optical fiber. We can now also detect time dilation due to a change in height near Earth’s surface of less than 1 meter. This technique may be extended to the field of geodesy, with applications in geophysics and hydrology as well as in space-based tests of fundamental physics.

So you might want to review that and then see if you can explain it without relativity. That would be interesting.

edit on 3-2-2014 by Arbitrageur because: clarification

Thats one of the things people misunderstand Einsteins equations have been proven to be right. They just here the word theory and dont understand what it means in science.

reply to post by swanne


You can't use the classical formula distance = time * velocity in order to calculate the relative speeds of the two lights towards the moving observer.

why don't we see distance as time difference ??
I don't want to explain it with the train example OP posted... but let me put it this way...

let say we have 2 clocks A B, atom clocks, light clocks or whatever is more accurate.
if those clocks together and not moving both show 00:00 and after 12 Hours 12:00 and so on, you can say they are synchronised.
Now the clocks move away from each other, what speed any of those clocks have doesn't matter, all that matters is the relative speed to each other. Let's assume both clocks move away from the Earth as the middle point ( Observer )
After 24 Hours those two clocks are separated by 24 light hours. ( yes, let them separate by the speed of light )

What time is clock A "seeing" on the clock B ? Must be 24 Hours less than A, as it takes 24 Hours for the information to propagate from clock B to A.

What time is clock B "seeing" on the clock A ? Must be 24 Hours less than B, as it takes 24 Hours for the information to propagate from clock A to B.

Both clocks can say the other clock is running late.

What time on Earth ( Observer ) can "see" on this clocks ? 12 Hours difference in every one of the clocks.

Time dilatation is not an physical effect, it's an observation related with distance.
If I, on Earth, look at any of this two clocks as they move, I well observe the time "slow down" in half till 24 Hours later I see 12 Hours difference on the "moving" clock.
For clock A and B they "stop ticking" as the relative speed is C

Loot at Gravity, what is this force doing to matter. It decreases the distance between 2 masses till they get close enough.
( don't want really to discuss how gravity works, it's always just theories and nothing solid )
Where is the source of Gravity force, it is doing work constantly, so where is the plug

more interesting it will become if the two clocks move at 1 C relative to Earth in the middle
those relative speed is 2 C. Clock A is not seeing clock B at all till they stop.

...

reply to post by ImaFungi


Adding to this. I think a great analogy to why a clock raised above the surface becomes non synchronized with the same clock on the surface is; Imagine 2 runners who (hypothetically for thought experiment) can only run exactly 5 mph at all times. Now I know those oval tracks for running races are calibrated so that there is no advantage no matter what lane you are in (the start and finished lines are shifted to be equal distances), but imagine if they werent, and the starting line was straight equal and the finish line was straight equal from the inside lane to the outer lane, the 5 mph runner on the inside lane would beat the 5 mph runner on any non inside lane every time. I believe a similar thing happens when an 'equally running clock' in the same reference 'lane' is removed from that reference lane and place in a more outer one such as elevated, if you imagine the surface of the earth to be the inside lane, and anything above it, increasingly outer.

A question about light. If light does have a definite speed (no matter how fast), dosen't that mean its has mass? If light weighs nothing, why isin't light speed infinite?

Oannes
A question about light. If light does have a definite speed (no matter how fast), dosen't that mean its has mass? If light weighs nothing, why isin't light speed infinite?

Light has no rest mass and it's never at rest. Some school teachers say it has "relativistic mass" but Einstein cautioned against using that concept (some teachers do it anyway).

I'm not sure why the speed of light has the value it has, but Michio Kaku says when we get infinities in physics, it usually means we made a mistake (he was referring to infinite density as an example but he was also generalizing).

I can turn your question around, and ask you, "why would it be infinite?". I don't know of any reason why it should be.

Also the equation E=mc^2 suggests to me that the speed of light c is a very important parameter, since in that equation it helps define matter energy equivalence. It's telling us something very fundamental about the universe.

Maybe if we ever develop a "theory of everything" or even a unified field theory, we might have a better understanding of why some constants like the speed of light have the values they have. But that's not necessarily so, as it's possible even a theory of everything might say "these are the observed values of the fundamental constants, and no deeper explanation of why they have these values has been found".

dragonridr
Thats one of the things people misunderstand Einsteins equations have been proven to be right.

I would say they're consistent with observation. Richard Feynman said no scientific theory can be proven right, they can only be proven wrong by contradictory observations. I think he's probably right.

Ptolemy's model of epicycles comes to mind, where observations were relatively consistent with this model, in Ptolemy's time, but this consistency with observations didn't prove the model as we now know.

Even Einstein was working on a unified theory that was more comprehensive than relativity, so he didn't think it was complete. It's a very useful model, and people that think they have a better idea to replace relativity will soon find there is a lot more evidence supporting relativity than they think.

Oannes
A question about light. If light does have a definite speed (no matter how fast), dosen't that mean its has mass? If light weighs nothing, why isin't light speed infinite?

Because it is 'something that actually exists'. Stating that something that exists speed can 'regularly' be infinite is a bit, strange and/or impossible. Anything that ever exists in any way will be limited in some way and some sense. It appears that light is the upper limit as to how fast a 'somethingness' in the universe can move.

This insinuates (I think perhaps) that EM field/light field is a fixed medium of sorts. But back to you saying why isnt light speed infinite, because define infinite, would it have a value, or would there be no upper bound limit as to how fast light could travel, surely the hypothetical upper limit would be (if light could travel at differing speeds in 'vacuum') taking all the energy that exists besides one little area of light field, and using all that energy to accelerate the light, would that make that light go infinite speed according to your definition of the terms? But then it wouldnt truly be infinite right, because that would be a limit.

You say, if light does have a definite speed no matter how fast. There is no question of matter how fast, it is always as fast as light, it is a constant speed (very supposedly). You know the EM spectrum, X rays and micro waves and radio waves and etc.? Those are all the same phenomenon in terms of an electron which is coupled to the EM field being accelerated, the difference of which between them is not their speed of propagation, but the energy frequency and wavelength associated with the energy that was involved with accelerating the electron.

It would be as if you were hovering over a pond, and any time you touched your finger to the pond, or dropped a rock into the pond, big or small, throwing hard or gently, the waves of water emanating from the point of mass contact, would propagate outwardly at the same speed. But the intensity at which you forced contact with the medium would cause the waves to take the forms of different frequency. The EM field (which I dont know much about) is different then this in the sense that its supposed not a 2d surface like this water example (though from my questioning of those in the know, it seems that EM radiation does propagate similar to the surface example, like a 2d plane, rather then a 3d sphere) but a 3d field, and the explanations of which are whacky and baffling and defy logic, but I suggest you look up about them none the less.

Light is said to have no mass because while it exists as light it has no mass maybe, hm, I think it has to do with masses definition regarding resistance to acceleration, where as light does not resist, and it is not even accelerated, it is automatic reaction of light velocity.

If we have an apple and you throw it at my face, after it hits my face most likely the apple will still exist, this is because it is an object composed of many objects which all have mass/rest mass and therefore the apple has mass. Einsteins reletivity and equivalence principle that famous equation, states that there is a relationship between an increase of energy of a rest mass, and the affect then of that rest mass being more massive. This is why an apple rested up against my face causes less force of sensation and detection and impact, then an apple thrown at my face, the energy of the arm transfers to the apple, at which point if that apple weighed 1/4 of a pound, depending on how fast it was thrown perhaps it would have the impact of a mass that weighed 2 pounds.

Light only exists at its speed, and when it hits your face it ceases to exist. The exact energy associated with the light field carrying the force from the accelerated electron/s go from electrons at point A, to electrons at point B, the EM radiation is the force carry, just as when you listen to the radio there is a point A of creation of light, and point B of reception, the moment it is received the light ceases to exist, it does not add mass to an object like smushing two apples together adds mass to the original apple, but it is a transfer of energy.

The frequency that the original electron is caused to vibrate at, is sent at the speed of light (through vacuum) to surrounding electrons, which then take on that frequency of vibration, the electron does not gain mass, in the sense of rest mass, but it does gain energy, which can be related to mass I suppose. So I hope someone else answers you, because I dont know.

Oannes
A question about light. If light does have a definite speed (no matter how fast), dosen't that mean its has mass? If light weighs nothing, why isin't light speed infinite?

light is not a mass ( physical object like Atom, Proton or Electron )
light, Microwave, Radio... all Electro - Magnetic phenomena is "just" a disturbance in the EM field.
There is nothing that actually moves, what looks like movement is the change in the tension on the EM field and it propagates with the speed we measure.
This change in the EM field is what cares the signal you call light.

KrzYma

Oannes
A question about light. If light does have a definite speed (no matter how fast), dosen't that mean its has mass? If light weighs nothing, why isin't light speed infinite?

light is not a mass ( physical object like Atom, Proton or Electron )
light, Microwave, Radio... all Electro - Magnetic phenomena is "just" a disturbance in the EM field.
There is nothing that actually moves, what looks like movement is the change in the tension on the EM field and it propagates with the speed we measure.
This change in the EM field is what cares the signal you call light.

Thats a nice description. The curiosity I cant help but having in regards to those statements, is it implies the EM field is "somethingness (energy/matter/something)". If the entire EM field exists,and can have its tension changed, doesnt this imply that the EM field is an object or substance or material or energy of sorts? Does the EM field have a rest mass, a rest tension so to speak, a homogenous energy value when not disturbed?

ImaFungi

Oannes
A question about light. If light does have a definite speed (no matter how fast), dosen't that mean its has mass? If light weighs nothing, why isin't light speed infinite?

Because it is 'something that actually exists'. Stating that something that exists speed can 'regularly' be infinite is a bit, strange and/or impossible. Anything that ever exists in any way will be limited in some way and some sense. It appears that light is the upper limit as to how fast a 'somethingness' in the universe can move.

This insinuates (I think perhaps) that EM field/light field is a fixed medium of sorts. But back to you saying why isnt light speed infinite, because define infinite, would it have a value, or would there be no upper bound limit as to how fast light could travel, surely the hypothetical upper limit would be (if light could travel at differing speeds in 'vacuum') taking all the energy that exists besides one little area of light field, and using all that energy to accelerate the light, would that make that light go infinite speed according to your definition of the terms? But then it wouldnt truly be infinite right, because that would be a limit.

You say, if light does have a definite speed no matter how fast. There is no question of matter how fast, it is always as fast as light, it is a constant speed (very supposedly). You know the EM spectrum, X rays and micro waves and radio waves and etc.? Those are all the same phenomenon in terms of an electron which is coupled to the EM field being accelerated, the difference of which between them is not their speed of propagation, but the energy frequency and wavelength associated with the energy that was involved with accelerating the electron.

It would be as if you were hovering over a pond, and any time you touched your finger to the pond, or dropped a rock into the pond, big or small, throwing hard or gently, the waves of water emanating from the point of mass contact, would propagate outwardly at the same speed. But the intensity at which you forced contact with the medium would cause the waves to take the forms of different frequency. The EM field (which I dont know much about) is different then this in the sense that its supposed not a 2d surface like this water example (though from my questioning of those in the know, it seems that EM radiation does propagate similar to the surface example, like a 2d plane, rather then a 3d sphere) but a 3d field, and the explanations of which are whacky and baffling and defy logic, but I suggest you look up about them none the less.

Light is said to have no mass because while it exists as light it has no mass maybe, hm, I think it has to do with masses definition regarding resistance to acceleration, where as light does not resist, and it is not even accelerated, it is automatic reaction of light velocity.

If we have an apple and you throw it at my face, after it hits my face most likely the apple will still exist, this is because it is an object composed of many objects which all have mass/rest mass and therefore the apple has mass. Einsteins reletivity and equivalence principle that famous equation, states that there is a relationship between an increase of energy of a rest mass, and the affect then of that rest mass being more massive. This is why an apple rested up against my face causes less force of sensation and detection and impact, then an apple thrown at my face, the energy of the arm transfers to the apple, at which point if that apple weighed 1/4 of a pound, depending on how fast it was thrown perhaps it would have the impact of a mass that weighed 2 pounds.

Light only exists at its speed, and when it hits your face it ceases to exist. The exact energy associated with the light field carrying the force from the accelerated electron/s go from electrons at point A, to electrons at point B, the EM radiation is the force carry, just as when you listen to the radio there is a point A of creation of light, and point B of reception, the moment it is received the light ceases to exist, it does not add mass to an object like smushing two apples together adds mass to the original apple, but it is a transfer of energy.

The frequency that the original electron is caused to vibrate at, is sent at the speed of light (through vacuum) to surrounding electrons, which then take on that frequency of vibration, the electron does not gain mass, in the sense of rest mass, but it does gain energy, which can be related to mass I suppose. So I hope someone else answers you, because I dont know.

Well as usual im going to muddy the waters actually light can travel faster weve done it has to do with its wave function. Here ill let you read the article.

abcnews.go.com...