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sdsperth
2018-Mar-19, 10:32 AM
I was always happy with the idea that mass was frozen energy and hence as energy was applied to a particle, it's mass increased.

Now I hear that the mass only "appears" to increase. Wha???

My girlfriend's mass appears to increase although she assures me that it hasn't. Hopefully it's not the same thing.

How can mass appear to increase? Does it mean gravitational force increases? I'm told not because no matter how fast a particle travels, I'm assured it cannot turn into a black hole.

selden
2018-Mar-19, 10:46 AM
Can you provide a reference for this "appears" phenomenon? By itself, your description seems to vague to me to be able to comment in any detail.

The evidence that I'm aware of (specifically, the way that particle accelerators work) indicates that the mass of highly energetic particles does indeed increase as their velocity increases.

Ken G
2018-Mar-19, 11:10 AM
The issue here is what is meant by "mass." In the equation E = mc2, mass is "relativistic mass," which increases like the Lorentz gamma factor times the "rest mass." Rest mass is invariant and does not increase. Modern preferences say mass is always "rest mass," the mass in the frame of the object, which is an innate property and does not change. Relativistic mass used to get used a lot because it allows the equations to retain their Newtonesque form, nowadays it is regarded as more important to stress that there is an invariant property there than it is to retain Newtonesque form. Forward looking rather than backward looking, essentially.

ShinAce
2018-Mar-19, 12:14 PM
Honestly, the concept of rest mass is flawed. Most of the mass of your own body is relativistic mass.

A proton is about 2000 times as heavy as an electron, yet the three quarks inside the proton have masses similar to an electron. So 5+5+10 = 2000. The other 1980 electrons worth of mass is relativistic mass.

plphy
2018-Mar-19, 12:34 PM
Presumably, in this context the term "apparent" refers to the fact that the mass increase is different in different reference systems.

For example, if you observe a rocket passing by the Earth at high speed and you determine the mass of the astronaut's suitcase (or some other object in the rocket), you will find a relativistically increased mass of the suitcase. The astronaut, on the other hand, will measure only the rest mass of her suitcase.

So in your reference system (where the Earth is at rest), the suitcase has increased mass while at the same time in the astronaut's reference system (where the rocket is at rest) the suitcase has only rest mass. There is no contradiction here because mass is a quantity which depends on the reference system in which it is measured. Measurements with respect to different reference systems may give different results.

This dependence on reference systems occurs often and is not a specifically relativistic concept. For example, wind speed and direction as measured on a moving boat are different from wind speed and direction as measured by an observer on land. Sailors call this effect the "apparent wind" (https://en.wikipedia.org/wiki/Apparent_wind).

Bye,
Thomas

Shaula
2018-Mar-19, 12:52 PM
Honestly, the concept of rest mass is flawed. Most of the mass of your own body is relativistic mass.

A proton is about 2000 times as heavy as an electron, yet the three quarks inside the proton have masses similar to an electron. So 5+5+10 = 2000. The other 1980 electrons worth of mass is relativistic mass.
As my focus has always been particle physics I'd say exactly the opposite. The concept of relativistic mass is flawed and only rest mass really makes sense. Relativistic mass is just energy, scaled while rest mass is an invariant property.

As Ken says, relativistic mass is used as a shortcut to carry on using Newtonian like equations in domains where you should be using relativistic ones. It induces far less confusion just to ditch the concept of relativistic mass and use the right equations!

Ken G
2018-Mar-19, 01:50 PM
Honestly, the concept of rest mass is flawed. Most of the mass of your own body is relativistic mass.I know what you're saying, but a proton is a system that does have an invariant rest mass. That's its rest mass in any coordinate system and reference frame. But no one said that rest mass had to be the sum of the rest masses of its elementary constituents. So the problem is not with the rest mass concept, it is with the incorrect supposition that rest masses are simply additive over the constituents of a particle. Put differently, the concept is really rest energy. So we have not lost the concept of the equivalence of mass and internal energy, what we've done away with is the idea that mass is a concept that should be regarded as frame dependent.

But there are still some ambiguities in the language. For example, if we take a bowling ball, it has an invariant rest mass. But if we heat up the bowling ball at rest, its mass increases due to the equivalence of mass and energy. Should we then say that the hot bowling ball has a higher rest mass? If that mass is invariant to reference frame, I would say yes. Then for the proton, if the proton is not in its internal ground state, but rather is in some kind of internal excited state, does it have a higher rest mass? The language is a bit unclear there, perhaps we should speak of "ground rest mass", meaning the mass of a proton in its ground state in its own reference frame. But the lifetimes of internal excited states are so short that I think people normally consider excited states as being part of interactions between particles moreso than intrinsic to the particle itself, so the issue doesn't really come up in the common parlance.

Grey
2018-Mar-19, 04:17 PM
Then for the proton, if the proton is not in its internal ground state, but rather is in some kind of internal excited state, does it have a higher rest mass? The language is a bit unclear there, perhaps we should speak of "ground rest mass", meaning the mass of a proton in its ground state in its own reference frame. But the lifetimes of internal excited states are so short that I think people normally consider excited states as being part of interactions between particles moreso than intrinsic to the particle itself, so the issue doesn't really come up in the common parlance.In some circumstances, we do consider this not only a different mass, but an entirely different particle. For example, the Delta+ (https://en.wikipedia.org/wiki/Delta_baryon) is made up of two up quarks and a down quark, just like a proton. Really, it's just a higher energy excitation of a proton (it's got a 3/2 spin as well, instead of a 1/2 spin). But in particle physics, it's usually treated as a separate particle, with its own rest mass and other properties. Similarly, the Delta0 is essentially an excited state of a neutron (there are also the Delta++ and the Delta-, which don't have lower energy analogs), and there are other baryons that are excited states of lower mass baryons.

grant hutchison
2018-Mar-19, 04:27 PM
How can mass appear to increase? Does it mean gravitational force increases? I'm told not because no matter how fast a particle travels, I'm assured it cannot turn into a black hole.This is another rich source of confusion, I think. In GR, the gravitational effect of a moving object does increase - it just doesn't look the same as the gravitational field of a stationary object with the same mass+energy. Which is why you can't make something into a black hole by accelerating it.
The event horizon that forms around a black hole is an invariant property of spacetime - every observer must have the same understanding of which photon trajectories can escape to infinity, and which will hit the singularity. So we can't have a situation in which a stationary observer sees no black hole event horizon, but an observer in relative motion sees a black hole event horizon. What the observer in relative motion sees is the gravitational field of a moving object, not the gravitational field of a stationary object of increased mass.

Grant Hutchison

Ken G
2018-Mar-19, 07:50 PM
In some circumstances, we do consider this not only a different mass, but an entirely different particle. For example, the Delta+ (https://en.wikipedia.org/wiki/Delta_baryon) is made up of two up quarks and a down quark, just like a proton. Really, it's just a higher energy excitation of a proton (it's got a 3/2 spin as well, instead of a 1/2 spin). But in particle physics, it's usually treated as a separate particle, with its own rest mass and other properties. Similarly, the Delta0 is essentially an excited state of a neutron (there are also the Delta++ and the Delta-, which don't have lower energy analogs), and there are other baryons that are excited states of lower mass baryons.
That's interesting, you are managing to avoid the concept of "ground rest energy" by regarding excited states as different particles! So every particle is in its ground state by convention. Of course this is not the convention for atoms! Perhaps the difference is that atomic excited states represent tiny increases in mass-energy, but that is not the case for the excited states you are talking about. This leads us to the question, how much of a change in the rest energy is needed before we regard something as a new particle? (I always enjoy pointing out how intimately our arbitrary choices of language are related to what we regard as the "true reality" in physics, here the reality of the "different particle" concept.)

ShinAce
2018-Mar-20, 02:56 AM
I know what you're saying, but a proton is a system that does have an invariant rest mass. That's its rest mass in any coordinate system and reference frame. But no one said that rest mass had to be the sum of the rest masses of its elementary constituents. So the problem is not with the rest mass concept, it is with the incorrect supposition that rest masses are simply additive over the constituents of a particle. Put differently, the concept is really rest energy. So we have not lost the concept of the equivalence of mass and internal energy, what we've done away with is the idea that mass is a concept that should be regarded as frame dependent.


I would agree that we would agree if talking about it over a pint.

Let me ask you, what is the difference between the charge of an electron and the bare charge of an electron? Isn't the bare charge invariant, while the charge is dependent upon the energy of interaction? Isn't the bare mass invariant, while the mass is dependent upon the energy of interaction? Is the charge of the electron truly increasing as we collide it at higher speeds? Is the mass of the proton increasing as we collide it at higher speeds?

Allow me to rephrase it. Rest mass is defined as the mass of something at rest. Nothing more and nothing less. It is not a specific and well defined property other than what is observed. The same can be said of the relativistic mass. It is what is observed.

Ken G
2018-Mar-20, 12:51 PM
I would agree that we would agree if talking about it over a pint.

Let me ask you, what is the difference between the charge of an electron and the bare charge of an electron? Isn't the bare charge invariant, while the charge is dependent upon the energy of interaction? Isn't the bare mass invariant, while the mass is dependent upon the energy of interaction? Is the charge of the electron truly increasing as we collide it at higher speeds? Is the mass of the proton increasing as we collide it at higher speeds?

Allow me to rephrase it. Rest mass is defined as the mass of something at rest. Nothing more and nothing less. It is not a specific and well defined property other than what is observed. The same can be said of the relativistic mass. It is what is observed.I agree that ultimately, clarity is all that is required-- one can use the terms rest mass and relativistic mass as much as one likes, as long as the meaning is clear. But I think the modern preference for rest mass over relativistic mass stems from a desire to place quantities that are frame and coordinate independent into a different box, and regard them in some sense as "more real" than what is affected by the reference frames of the various observers looking on. One then interprets relativity as a kind of list of invariant quantities along with the rules for how they will be observed in different reference frames, where the former gets interpreted as what "really is" and the latter gets interpreted as some kind of "observer bias." No doubt that approach reflects a spirit of rationalism over empiricism, similar to models that say that we orbit the Sun instead of what our observations appear to show (that the Sun orbits us). I would say modern science has a rather schizophrenic relationship between rationalist tendencies to elevate models into what is, and empiricist tendencies to stick to the facts ma'am. I've heard people say that when comparing observations to some theory, one should leave the observations as they are and "bring the theory to them," yet when we find theories in textbooks they usually precede the observations used to validate them-- if we even get the observations at all.

sdsperth
2018-Mar-21, 03:59 AM
Presumably, in this context the term "apparent" refers to the fact that the mass increase is different in different reference systems.

For example, if you observe a rocket passing by the Earth at high speed and you determine the mass of the astronaut's suitcase (or some other object in the rocket), you will find a relativistically increased mass of the suitcase. The astronaut, on the other hand, will measure only the rest mass of her suitcase.

So in your reference system (where the Earth is at rest), the suitcase has increased mass while at the same time in the astronaut's reference system (where the rocket is at rest) the suitcase has only rest mass. There is no contradiction here because mass is a quantity which depends on the reference system in which it is measured. Measurements with respect to different reference systems may give different results.

This dependence on reference systems occurs often and is not a specifically relativistic concept. For example, wind speed and direction as measured on a moving boat are different from wind speed and direction as measured by an observer on land. Sailors call this effect the "apparent wind" (https://en.wikipedia.org/wiki/Apparent_wind).

Bye,
Thomas

Thanks Thomas. So will a rocket flying by at immense speed measure the mass of the earth to be increased? I must have this wrong as those on earth will measure a low mass rocket flying by and a tiny resultant increase in gravitational attraction, but those on the rocket will measure an enormous mass planet flying by with a gigantic increase in gravitational attraction. Please set me straight.

sdsperth
2018-Mar-21, 04:00 AM
Thankyou all for this wonderful discussion. I have learned much, but sadly it seems my girlfriend's mass will remain a mystery.

Ken G
2018-Mar-21, 09:44 AM
Thanks Thomas. So will a rocket flying by at immense speed measure the mass of the earth to be increased? I must have this wrong as those on earth will measure a low mass rocket flying by and a tiny resultant increase in gravitational attraction, but those on the rocket will measure an enormous mass planet flying by with a gigantic increase in gravitational attraction. Please set me straight.That's what grant hutchison was telling you, it is not straightforward to consider the gravity of a huge planet that is nearing the speed of light relative to your rocket. You could not simply take the relativistic mass and otherwise treat the gravity as if that's all that was different about it. You would do much better by simply taking the rest mass of the planet, not its relativistic mass. (In fact, it is often said that Newtonian gravity is only wrong by a factor of 2 when calculating its effect on light.) However, if the planet was incredibly hot, so it had lots of randomly directed motions within it, then all that internal energy would indeed increase the rest mass of the planet and would show up pretty simply in the gravity. So it really depends on what you mean by "relativistic mass," you don't want to just take the rest mass and multiply by the gamma factor of relative motion, if it is the gravity you are interested in.

Ken G
2018-Mar-21, 09:46 AM
Thankyou all for this wonderful discussion. I have learned much, but sadly it seems my girlfriend's mass will remain a mystery.
I'm certain you did not intend for this remark to come out sounding sexist.

Shaula
2018-Mar-21, 12:17 PM
You would do much better by simply taking the rest mass of the planet, not its relativistic mass.
Or better yet forget relativistic mass entirely and actually use GR because this is a case that clearly falls within its domain of applicability and not the domain of applicability of some pseudo-Newtonian bodge involving a messy attempt to hide relativistic effects with a simple scaling factor. The warp you would see is related to the stress-energy-momentum tensor, of which rest mass is just a component.

plphy
2018-Mar-21, 10:43 PM
So will a rocket flying by at immense speed measure the mass of the earth to be increased?

It is important to appreciate that in physics some quantities depend on the reference system which is used to describe them, and descriptions referring to different reference systems may appear contradictory but aren't. This is not only true in relativity, it is already true in classical mechanics and all other branches of physics.

Some quantities do not depend on a reference system. The "number of objects" is an example. If you count eight eggs in your basket, every other observer will count eight eggs as well, regardless of their state of motion with respect to you.

Other quantities must refer to a reference system. For example, much of classical physics is concerned with describing trajectories of objects subjected to some force. The trajectories are usually described by giving the objects' coordinates as a function of time, and in order to give coordinates, you first have to define a coordinate system (or more generally: a reference system).

Suppose you want to describe the position of your house. You choose some specific reference system and you find that the house happens to be on the x-axis at x = 3 km. Your girlfriend does the same but uses a different reference system (which is as good as yours) and finds x = 10 km. Who is right? The house cannot be in two places at the same time! It's not, we just have two descriptions which are different because they refer to two different reference systems. There are methods to convert a description from one reference system to the other, and using such a method you find that if you convert your description to the reference system used by your girlfriend, you find precisely her description. (In classical mechanics, the conversion method is simply to add a certain offset to the coordinates; in relativity, the method is slightly more complicated.)

Now let's consider speed. You are standing at a train station, a train with your girlfriend and her suitcase is passing by at 100 km/h. You observe that her suitcase moves at 100 km/h. Your girlfriend on the other hand is entitled to consider herself at rest and she insists that her suitcase has speed zero. Again, there is no contradiction between her suitcase being at rest and moving at the same time: these are two different descriptions referring to different reference systems (in classical mechanics, speed is converted from one reference system to the other by adding the speed difference of the reference systems; in relativity, the method is slightly more complicated.)

Now consider the kinetic energy of the two suitcases. Your girlfriend insists that her suitcase has kinetic energy zero, while you insist that it has a few kilojoules of kinetic energy. Again, no real contradiction exists.

If we switch reference systems, a suitcase which had zero kinetic energy now suddenly has non-zero kinetic energy. This does not mean that energy has appeared out of nothing, it only means we have changed from one possible description to a different one, and each one is consistent in itself. In particular, energy conservation is not violated. In the first system (which we used previously), the kinetic energy was zero and remains zero. In the other system (which we then started to use), the kinetic energy was non-zero and remains non-zero.

Some people ask: Is the change in energy real or not real? But this question is beside the point and both answers are misleading. To say that the change is real would imply that the energy of the suitcase has really changed, which is not the case (only the description has changed). To say that the change is not real would imply that we are somehow mistaken about there being an energy difference. There definitely is a difference, but it is only a difference in descriptions. It is more appropriate to say: kinetic energy is a reference system dependent quantity. It can have different values in different reference systems at the same time.

Sometimes this is also expressed by saying: the difference is apparent. Here "apparent" is not meant in the sense of "unreal" or "deceiving", but simply in the sense of "as observed / measured / described by the respective observer".

Everything said so far is true in classical mechanics as well as in relativity (only the methods used to convert descriptions between reference frames are different). One major difference between classical mechanics and relativity is: Some quantities which are reference system dependent in classical mechanics are not in relativity. For example: In classical mechanics all speeds are reference system dependent (we saw an example above). In relativity this is also true, but with the exception of light speed: An object which moves with light speed in one reference system also moves with light speed in all other reference systems.

On the other hand, there are quantities which are not reference system dependent in classical mechanics but which are reference system dependent in relativity. For example, the lengths of objects. In different reference systems one and the same object is described as having different lengths. Again, the question whether the length contraction of a moving object is real or not is misleading. It is not real in the sense of the object having been compressed by some force acting on it. But it is also not unreal in the sense that we are somehow mistaken when we state that there is a difference. Length is a reference system dependent quantity.

Another example is the length of time intervals: Different observers describe the same time interval as "dilated" to different degrees.

And finally: In relativity mass is a reference system dependent quantity. It has different values in differently moving reference systems. The difference between a mass at rest and a moving mass is not real in the sense that energy has somehow condensed onto the mass.

If you want to know how a mass which you measured in your own reference system is measured and described in a different reference system, you need to "change reference systems" by applying the relevant relativistic formulas. The result is: If you are at rest on Earth and watch a rocket passing by at very high speed, you find the mass of the rocket increased by a certain factor with respect to identical rockets being at rest on Earth. The mass of the Earth is, well, one Earth mass. At the same time your girlfriend in the rocket determines that the mass of the Earth has increased (by the same factor you observed for the rocket), while the mass of her rocket is simply the mass these rockets usually have. This result agrees with the premise that all (inertial) reference systems are equivalent: Everyone measures their own masses as remaining constant and all the moving masses as increased. This sounds weird but it is logically consistent.

Sorry for being so long-winded. I'm afraid it won't help you to really understand at an intuitive level how the mass increase comes about, but I hope it's useful to clear up a few potential misunderstandings.

Regards,
Thomas

sdsperth
2018-Mar-22, 03:58 PM
If you want to know how a mass which you measured in your own reference system is measured and described in a different reference system, you need to "change reference systems" by applying the relevant relativistic formulas. The result is: If you are at rest on Earth and watch a rocket passing by at very high speed, you find the mass of the rocket increased by a certain factor with respect to identical rockets being at rest on Earth. The mass of the Earth is, well, one Earth mass. At the same time your girlfriend in the rocket determines that the mass of the Earth has increased (by the same factor you observed for the rocket), while the mass of her rocket is simply the mass these rockets usually have. This result agrees with the premise that all (inertial) reference systems are equivalent: Everyone measures their own masses as remaining constant and all the moving masses as increased. This sounds weird but it is logically consistent.


Thanks Thomas. I'm happy with this explanation - it makes perfect sense to me that both measure the same mass increase in the other. Can you point me to the relativistic formulas that will tell me how much that increase is please.

grant hutchison
2018-Mar-22, 04:51 PM
You'll find the relevant equation on the Physics FAQ page "Does Mass Change With Velocity? (http://www.phys.ncku.edu.tw/mirrors/physicsfaq_old/Relativity/SR/mass.html)" (third equation). The page also rehearses most of the arguments given here for why relativistic mass is a potentially misleading concept that most physicists avoid using.
And it's perhaps worth repeating that the gravitational effect of a moving object is not the same as the gravitational effect of a static object with mass equal to the "relativistic mass" of the moving object. Which is another reason to avoid the concept of relativistic mass.

Grant Hutchison

trinitree88
2018-Mar-22, 06:30 PM
Thanks Thomas. I'm happy with this explanation - it makes perfect sense to me that both measure the same mass increase in the other. Can you point me to the relativistic formulas that will tell me how much that increase is please.

sdsperth try:https://arxiv.org/abs/1803.07909

pete

grant hutchison
2018-Mar-22, 07:13 PM
sdsperth try:https://arxiv.org/abs/1803.07909Mass as a tensor rather than a scalar?
That seems like the type specimen of a solution being more complicated than the problem it's trying to address.

Grant Hutchison

wd40
2018-Mar-23, 11:53 AM
Remarkable that all these time dilation, mass increase, length shortening and paradox calculations have to be made because of the null result of one experiment!

Strange
2018-Mar-23, 12:01 PM
Remarkable that all these time dilation, mass increase and length shortening calculations have to be made because of the null result of one experiment!

That isn't really the reason. And there are multiple experiments that confirm special and general relativity.

wd40
2018-Mar-23, 12:08 PM
That isn't really the reason. And there are multiple experiments that confirm special and general relativity.

As Hawking RIP said:

"If General Relativity is wrong, why have all experiments thus far supported it? The reason that we haven’t yet noticed any discrepancy with observation is that all the gravitational fields that we normally experience are very weak." (Briefer History of Time p102)

Grey
2018-Mar-23, 01:27 PM
As Hawking RIP said:

"If General Relativity is wrong, why have all experiments thus far supported it? The reason that we haven’t yet noticed any discrepancy with observation is that all the gravitational fields that we normally experience are very weak." (Briefer History of Time p102)Here (https://books.google.com/books?id=DiBjCUibQo4C&pg=PA102&lpg=PA102&dq=%22If+General+Relativity+is+wrong,+why+have+all +experiments+thus+far+supported+it?+The+reason+tha t+we+haven%E2%80%99t+yet+noticed+any+discrepancy+w ith+observation+is+that+all+the+gravitational+fiel ds+that+we+normally+experience+are+very+weak&source=bl&ots=Jl4ajF0Yfl&sig=PdIK9bmMQeB-cDPibhHdH-Fqzzs&hl=en&sa=X&ved=0ahUKEwi02vrJxILaAhVrw4MKHct7Du0Q6AEIJzAA#v=on epage&q=%22If%20General%20Relativity%20is%20wrong%2C%20w hy%20have%20all%20experiments%20thus%20far%20suppo rted%20it%3F%20The%20reason%20that%20we%20haven%E2 %80%99t%20yet%20noticed%20any%20discrepancy%20with %20observation%20is%20that%20all%20the%20gravitati onal%20fields%20that%20we%20normally%20experience% 20are%20very%20weak&f=false)'s the context around that quote. It looks like Hawking is just referring to our expectation that general relativity probably does need to be modified when we get down to a scale where quantum effects are involved. He's not casting any doubt on the validity of general relativity in its normal domain (including, say, stellar mass black holes).

Ken G
2018-Mar-23, 03:08 PM
Indeed, it's ironic that he uses our experiences of weak gravitational fields to explain why GR works even though theoretical physicists expect it to break down somewhere, because actually the fields are so weak that our experience generally doesn't even require GR at all-- Newtonian gravity almost always serves. But the point is the same, and is repeated over and over throughout history: we only experience a small corner of the phenomena that our technology ultimately allows us to explore, so our theories will inevitably become more and more sophisticated (and often, more and more outrageous!) with time. This progress mirrors our own evolving mathematical sophistication to keep pace. (Consider that the mathematics that Newton needed to invent to describe his revolutionary theory is today taught to clever high-school kids.)

wd40
2018-Mar-25, 05:39 AM
That isn't really the reason.

What other reason was there for STR other than to explain MM?

Geo Kaplan
2018-Mar-25, 07:33 AM
What other reason was there for STR other than to explain MM?

Maxwell's equations, for one, with frame-independent c.

Hornblower
2018-Mar-25, 11:06 AM
What other reason was there for STR other than to explain MM?

What is STR? If it appears in this thread, the clunky search function is not helping me in finding it.

wd40
2018-Mar-25, 01:06 PM
Maxwell's equations, for one, with frame-independent c.

Einstein had to demonstrate how to fit a moving Earth into MM. Rather than allow the speed of light to vary, Einstein opted to vary time, mass and space.

In 1912 Einstein wrote:

“To fill this gap, I introduced the principle of the constancy of the velocity of light, which I borrowed from H. A. Lorentz’s theory of the stationary luminiferous ether” (The Collected Papers of Albert Einstein, Vol. 4. Doc. 8, p. 131).

“The term relativity refers to time and space. This led the Dutch professor, Lorentz, and myself to develop the special theory of
relativity” (Lorentz - The Einstein Theory of Relativity, Brentano, 1920, p11).

And in 1935, Einstein stated:

“The Lorentz transformation, the real basis of the special relativity theory, in itself has nothing to do with the Maxwell theory.” (“Elementary Derivation of the Equivalence of Mass and Energy”, Bulletin of the American Mathematical Society, Series 2, Vol. 41, 1935, p. 230).

slang
2018-Mar-25, 01:50 PM
What is STR? If it appears in this thread, the clunky search function is not helping me in finding it.

I assume special theory of relativity (https://en.wikipedia.org/wiki/Special_relativity). I guess it comes from trying to understand (or attack) science using quotes only, as was the sad standard when creationists attacked biology. Perhaps they still do, I stopped caring.

Strange
2018-Mar-25, 02:19 PM
What other reason was there for STR other than to explain MM?

For one thing there wasn’t “one experiment”.

Einstein’s motivation was mainly philosophical: that the principle of relativity was correct.


his thinking was influenced by the empiricist (https://en.m.wikipedia.org/wiki/Empiricism)philosophers David Hume (https://en.m.wikipedia.org/wiki/David_Hume) and Ernst Mach (https://en.m.wikipedia.org/wiki/Ernst_Mach). Regarding the Relativity Principle, the moving magnet and conductor problem (https://en.m.wikipedia.org/wiki/Moving_magnet_and_conductor_problem) (possibly after reading a book of August Föppl (https://en.m.wikipedia.org/wiki/August_F%C3%B6ppl)) and the various negative aether drift experiments were important for him to accept that principle — but he denied any significant influence of the most important experiment: the Michelson–Morley experiment.[70] (https://en.m.wikipedia.org/wiki/History_of_special_relativity#cite_note-stach-71)
https://en.m.wikipedia.org/wiki/History_of_special_relativity

Ken G
2018-Mar-25, 02:34 PM
The special theory of relativity. So the way science works is, there's an observation that motivates a new theory, and then the new theory gets tested all over the place in thousands of other experiments. I would have thought wd40 would already know this, on a science forum, so the question is puzzling.

grant hutchison
2018-Mar-25, 03:48 PM
Maxwell's equations, for one, with frame-independent c.
...
“The Lorentz transformation, the real basis of the special relativity theory, in itself has nothing to do with the Maxwell theory.” (“Elementary Derivation of the Equivalence of Mass and Energy”, Bulletin of the American Mathematical Society, Series 2, Vol. 41, 1935, p. 230).That quote doesn't mean what you seem to want it to mean. It's simply a non sequitur to Geo Kaplan's remark.

Grant Hutchison

Geo Kaplan
2018-Mar-25, 03:55 PM
Einstein had to demonstrate how to fit a moving Earth into MM. Rather than allow the speed of light to vary, Einstein opted to vary time, mass and space.

And in 1935, Einstein stated:

“The Lorentz transformation, the real basis of the special relativity theory, in itself has nothing to do with the Maxwell theory.” (“Elementary Derivation of the Equivalence of Mass and Energy”, Bulletin of the American Mathematical Society, Series 2, Vol. 41, 1935, p. 230).

You are engaging in disingenuous revisionism through selective quoting, wd40.

A fuller quote from that same paragraph in the BAMS paper provides the honest context for the partial quotation you provided. Einstein explicitly precedes that quote by saying:

"The special theory of relativity grew out of the Maxwell electromagnetic equations."


The rest of the paper you cite merely talks about how one could derive the Lorentz transformation independently of Maxwell, but that's irrelevant when we are talking about history. You made the false claim that SR was built on a single experiment. It was not. Indeed, Einstein repeatedly stated throughout his life that MM played essentially no role in stimulating the development of SR, citing Maxwell's equations as among the inspirations.

Geo Kaplan
2018-Mar-25, 04:15 PM
The special theory of relativity. So the way science works is, there's an observation that motivates a new theory, and then the new theory gets tested all over the place in thousands of other experiments. I would have thought wd40 would already know this, on a science forum, so the question is puzzling.

Extremely puzzling, especially in combination with the quote-mining. How SR came to be has been so thoroughly documented that it takes a certain skill and determination to get the history wrong.

grant hutchison
2018-Mar-25, 04:28 PM
Extremely puzzling, especially in combination with the quote-mining. How SR came to be has been so thoroughly documented that it takes a certain skill and determination to get the history wrong.A search on the three quotes presented by wd40 produces a unique link to a geocentrist tract entitled Galileo Was Wrong: The Church Was Right (http://www.academia.edu/35814658/Galileo_Was_Wrong_The_Church_Was_Right_Vol_1_12th_ Edition).
There is a cottage industry of out-of-context quote-mining among geocentrists and anti-relativists. Someone, somewhere, at some time, pulled these quotes cynically out of context, but after that the echo chamber takes over.

Grant Hutchison

ultramaryna
2018-Mar-25, 09:54 PM
The relativistic mass is a quite real thing, not apparent only, despite many of fantastic claims in this context.
This quantity has been directly visible - observed for decades in the experiments with accelerators, and many others.

And a situation is even rather opposite - contrary to these fantastic claims about invariability of the so-called proper - gravitational mass.

A simple sketch:

m = m_0\sqrt{1-2M/r} this means a mass is not invariant in the gravity, but it decreases simply in the gravity.

And now a simple mathematical proof of this fact.

1. during a free fall in a gravity the energy is conserved, thus:

m0 = const

2. but a speed of the falling mass grows, thus:
m = m gamma(v) = m0 = const

3. therefore, using the fact about a mass in a gravity, we get an equation to solve:

m_0 \frac{\sqrt{1-2M/r}}{\sqrt{1-v^2}} = m_0

thus:
\sqrt{1-2M/r} = \sqrt{1-v^2}

hence:
2M/r = v^2

And this is correct result, because this is the speed of a free falling body in the gravity - the so-called escape speed.

Ken G
2018-Mar-25, 10:14 PM
A search on the three quotes presented by wd40 produces a unique link to a geocentrist tract entitled Galileo Was Wrong: The Church Was Right (http://www.academia.edu/35814658/Galileo_Was_Wrong_The_Church_Was_Right_Vol_1_12th_ Edition).
There is a cottage industry of out-of-context quote-mining among geocentrists and anti-relativists. Someone, somewhere, at some time, pulled these quotes cynically out of context, but after that the echo chamber takes over.
Busted.

Geo Kaplan
2018-Mar-26, 04:40 AM
A search on the three quotes presented by wd40 produces a unique link to a geocentrist tract entitled Galileo Was Wrong: The Church Was Right (http://www.academia.edu/35814658/Galileo_Was_Wrong_The_Church_Was_Right_Vol_1_12th_ Edition).
There is a cottage industry of out-of-context quote-mining among geocentrists and anti-relativists. Someone, somewhere, at some time, pulled these quotes cynically out of context, but after that the echo chamber takes over.

Grant Hutchison

Nice sleuthing, Grant!

wd40
2018-Mar-26, 05:32 AM
A search on the three quotes presented by wd40 produces a unique link to a geocentrist tract entitled Galileo Was Wrong: The Church Was Right (http://www.academia.edu/35814658/Galileo_Was_Wrong_The_Church_Was_Right_Vol_1_12th_ Edition).


Are vols II & III on line?

Ken G
2018-Mar-26, 06:46 AM
A simple sketch:All you are saying is that if you want to use E = mc2, then m must be the "relativistic mass." The point is, however, many people don't use E = mc2 squared any more, because the m in that formula is not invariant to the coordinate system or reference frame. For example, particle accelerator physicists routinely use mass in energy units, rather than energies in mass units, expressly because when they want to conserve energy, they want to be talking about energy rather than mass. When they talk of rest mass, they will also use energy units, but that's because they regard the rest mass as a contribution to the energy, not as the entire energy.

Shaula
2018-Mar-26, 12:21 PM
All you are saying is that if you want to use E = mc2, then m must be the "relativistic mass."
Or you could use the correct, whole equation for energy momentum equivalence...

grant hutchison
2018-Mar-26, 03:00 PM
Nice sleuthing, Grant!It's not the first time (https://forum.cosmoquest.org/showthread.php?161009-Is-Lorentz-Contraction-Real&p=2352109#post2352109).
Nor is the first time we've been around the houses with wd40's misconception about the relationship between Michelson-Morley and SR (https://forum.cosmoquest.org/showthread.php?108434-Relativistic-farrago).

Grant Hutchison

ultramaryna
2018-Mar-26, 03:43 PM
All you are saying is that if you want to use E = mc2, then m must be the "relativistic mass." The point is, however, many people don't use E = mc2 squared any more, because the m in that formula is not invariant to the coordinate system or reference frame. For example, particle accelerator physicists routinely use mass in energy units, rather than energies in mass units, expressly because when they want to conserve energy, they want to be talking about energy rather than mass. When they talk of rest mass, they will also use energy units, but that's because they regard the rest mass as a contribution to the energy, not as the entire energy.

Any mass is a type of energy only.
In other words: this indestructible substance, which creates matter, doesn't exists at all.

ultramaryna
2018-Mar-26, 05:13 PM
Some direct consequences of the mass variability in a general case.

The Newtonian acceleration is correct for the free falling scenario from infinity only:
v^2 = 2M/r then: g(r) = -M/r^2, exactly.

but for any other case: v^2 <> 2M/r, the acceleration is different already!

especially for any orbital motion:
g(r) < -M/r^2, because v^2 < 2M/r, in this case,

thus the acceleration is now a little bigger than the Newtonian one,
and because of that fact the whole orbit precesses -
that is the real cause of the Mercury's apsidal precession.

Ken G
2018-Mar-26, 07:59 PM
It is well known that the concept of "relativistic mass" involves some conveniences, that's why it's called "relativistic mass" in the first place. Nevertheless, invariant mass is normally used instead, and the "conveniences" of relativistic mass are simply embedded into how the invariant mass interacts with the reference frame to produce the non-invariant quantity known as energy. Obviously people who like the energy concept are going to try to treat it as a fundamental quantity, but it's not an invariant quantity, making it an improper quantity for use in relativistic transformations.

ultramaryna
2018-Mar-27, 04:31 PM
It is well known that the concept of "relativistic mass" involves some conveniences, that's why it's called "relativistic mass" in the first place. Nevertheless, invariant mass is normally used instead, and the "conveniences" of relativistic mass are simply embedded into how the invariant mass interacts with the reference frame to produce the non-invariant quantity known as energy. Obviously people who like the energy concept are going to try to treat it as a fundamental quantity, but it's not an invariant quantity, making it an improper quantity for use in relativistic transformations.

The invariant masses exists in the Newtonian mechanics only.

The general equation for any motion, including the gravity filed, looks like this:
E = m_0 \frac{\sqrt{1-2M/r}}{\sqrt{1-v^2}} = const

https://en.wikipedia.org/wiki/Two-body_problem_in_general_relativity

"which is equivalent to a particle moving in a one-dimensional effective potential:
https://wikimedia.org/api/rest_v1/media/math/render/svg/210d1d65afe4074bce8b7cd49a7b6a65dc43b125

and this is in fact a second order approximation of the simple general equation only:
\sqrt{1-x} = 1 - 1/2 x + ...

grant hutchison
2018-Mar-27, 11:23 PM
The invariant masses exists in the Newtonian mechanics only.
...It's probably worth pointing out that this statement is immediately contradicted by the two equations that follow it, both of which contain invariant mass as a constant - m0 and m, respectively.

Grant Hutchison