A Serious Question from an Educated Layman

[El Hombre Invisible]

Objects A and B both simultaneously travel at half the speed of light in exact opposite directions and stop exactly one light year away. They then make the trip back to point "x" and compare notes.

There is no difference in this scenario and any other scenario with A being stationary and the size of a planet and B being in relative motion and the size of a meteor or spacecraft .

There's a huge difference. In the former scenario, neither A nor B can be at rest in one frame of reference - both require two different frames to describe themselves at rest: one for the outward journey, one for the return. In the latter scenario, A may be described as being at rest for the whole trip in a single frame of reference but B cannot. The two scenarios are entirely different.

 

[AgnosticPriest]

All the scenarios I've read about simultaneity, length contraction, time dilation, and twin paradox rely upon acceleration and deceleration, and they don't bother to point out that no experiment has been done yet outside the influence of magnetic and gravitic fields.

My argument remains that without the effects of inertia to consider, and without the interference of magnetism and gravity, time dilation and length contraction should not occur. All unchanging states of motion being relative, there is no reason why it should!

 

[εllipse]

My argument remains that without the effects of inertia to consider, and without the interference of magnetism and gravity, time dilation and length contraction should not occur. All unchanging states of motion being relative, there is no reason why it should!

In that case, what makes you think length contraction will even occur under a gravitational field? Einstein argued how gravity would affect space-time by using the equivalence principle and length contraction due to velocity (under special relativity). If you ignore length contraction in inertial frames, such arguments no longer hold for gravitation.

 

[El Hombre Invisible]

All the scenarios I've read about simultaneity, length contraction, time dilation, and twin paradox rely upon acceleration and deceleration, and they don't bother to point out that no experiment has been done yet outside the influence of magnetic and gravitic fields.

My argument remains that without the effects of inertia to consider, and without the interference of magnetism and gravity, time dilation and length contraction should not occur. All unchanging states of motion being relative, there is no reason why it should!

Simultaneity, length contraction and time dilation do not rely on acceleration. They can in principal be observed in inertial frames in which the subjects are also inertial. The resolution of the twins paradox relies on a change of reference frame, but that's a given - the twin's paradox is stated as having a change of reference frame... it isn't actually a paradox in SR. There would be no paradox at all if the traveling twin continued away from his bro forever at a constant velocity. Both twins would then observe time passing more slowly for the other, and as they do so in different reference frames this is not a paradox. Only when the traveling twin turns around (change of reference frame 1) and then stops back on Earth (change of reference frame 2 to match the other twin's) does the paradox occur because they end up in the same reference frame, but that's only because we are using SR theory to describe a series of events that SR was not intended to cover - changes in inertial frames (which in real terms means acceleration).

You seem to be saying that the lack of experiment of SR conclusions under SR conditions means that the phenomena would not occur under real SR conditions. This is a strange attitude. Real SR conditions are unlikely, as everything is subject to some acceleration/gravity. The conclusions of SR were arrived at using special inertial cases that do not reflect real life - hence 'special' - but arrived at via SR nonetheless. Only from SR were these phenomena found to be inevtiable - it makes no sense whatsoever to accept these phenomena and then say that SR isn't the reason. I know too little about GR to fully argue, but I would assume that the conclusions of SR are incorporated into it. If the cause of these phenomena in GR turned out to be different (i.e. due to acceleration) then that would be one hell of a coincidence.

 

[AgnosticPriest]

It seems to me that just about everyone here is saying the same thing. "It just is" doesn't cut it for me. I'm a "show me why and how" type of guy. I accept things as they are so long as they fit into the box of logic and reason. This is why I'm naturally drawn to science and shy away from philosophy and religion. What surprises me the most is that many physicists are beginning to sound like eastern mystics.

Things don't "just happen". There is a force at work in everything. When an effect is observed there is a reasonable and traceable explanation for it. Just because we haven't discovered it yet doesn't mean it doesn't exist. This is supposed to be the basis for all scientific interests. Where religious fanatics declare the unknown to be "god's territory" the true scientists are thrusting their noses deep into those areas and proving that it is NOT.

I understand that according to mathematical calculations when object A travels relatively away from object B at near light speeds and then returns, object A has experienced time dilation and length contraction. Based on even the limited amount of raw data on this theory I can accept that under normal circumstances this remains an undeniable fact.

However, what I cannot accept yet is that given a scenario where there is no inertia, there is no gravity, and there is no magnetism to influence the traveler these facts would apply as well. No one has yet experimented with it. All experiments thus far have been within the grasp of these influences. These influences taint the experiment and the data one gets is unreliable when viewing things from a universal perspective.

It's akin to someone in caveman times declaring that the world is flat and all things that go up will universally come down. All experiments the caveman is capable of performing will prove these facts and all who listen to him will be learning to follow a false doctrine based on the inability to see beyond their noses. The fact is not all things that go up will ever come down again, and the world is most definitely not flat.

And light is not necessarily the fastest speed in the universe.

Find a way to place a spacecraft outside the influences of gravity, magnetism, and inertia, supply the spacecraft with a form of propulsion which is capable of reaching and breaching the speed of light, and the craft will probably succeed with no ill effects. This is impossible to prove or disprove at this juncture in our technological age, and I have yet to see any definitive rebuttal. As long as I get responses that are just echoes of what other physicists SAY as opposed to raw data which has PROVEN me wrong, I am lead to believe there is a chance I could be right.

So, again, I plead my case, and thank all for their input with due respect...but still am left with my original request: Prove me wrong. Please. If I'm wrong, I want to know why.

 

[arildno]

However, what I cannot accept yet is that given a scenario where there is no inertia, there is no gravity, and there is no magnetism to influence the traveler these facts would apply as well.

What ARE you talking about?
What do you mean by "no inertia"??

 

[AgnosticPriest]

What ARE you talking about?
What do you mean by "no inertia"??

in·er·tia
n.
Physics. The tendency of a body to resist acceleration; the tendency of a body at rest to remain at rest or of a body in straight line motion to stay in motion in a straight line unless acted on by an outside force.

 

[selfAdjoint]

in·er·tia
n.
Physics. The tendency of a body to resist acceleration; the tendency of a body at rest to remain at rest or of a body in straight line motion to stay in motion in a straight line unless acted on by an outside force.

So, since in your simplistic view of physics inertia is undoubtedly an inherent property of matter, how, and more importantly WHY, should tests of relativity be done in its absence?

 

[El Hombre Invisible]

It seems to me that just about everyone here is saying the same thing. "It just is" doesn't cut it for me. I'm a "show me why and how" type of guy. I accept things as they are so long as they fit into the box of logic and reason. This is why I'm naturally drawn to science and shy away from philosophy and religion. What surprises me the most is that many physicists are beginning to sound like eastern mystics.

Woah woah woah! Wait a minute! No-one is saying the effect you describe is as it is because 'it just is'. You're the one suggesting "time dilation and length shortening of objects approaching the speed of light only occur because the things we have observed and experimented with were passing through magnetic and gravitic fields", a theory with no experimental evidence or mathematical model, and seems to pass only your criteria for a valid philosophical conjecture.

The effects of SR you describe, such as time dilation, were predicted by Einstein, previously unobserved, as a result of his theory based on two universal principals. Not only that, but it explained WHY those principals will always be true. Subsequent experimental evidence confirmed that Einstein's predictions were correct. That's far from 'it just is'. Give the guy some credit.

However, what I cannot accept yet is that given a scenario where there is no inertia, there is no gravity, and there is no magnetism to influence the traveler these facts would apply as well. No one has yet experimented with it. All experiments thus far have been within the grasp of these influences. These influences taint the experiment and the data one gets is unreliable when viewing things from a universal perspective.

I won't pretend to be even a novice at GR, but even I can see the flaw in this. Take two paths followed by two different particles. One is effected by a gravitational field, the other is free from any force or curvature whatsoever. Now, when the gravitated particle follows its path, it travels in what is to it (were it possible to have such a perspective) a straight line. What do you think the path of the unaccelerated particle would look like to it? If you figure this out, you figure out why an 'absolute' inertial frame is not logical. You only have to look at expansion to see that, even if you can determine an inertial frame within, say, a galaxy treated as a closed system, this galaxy is still relatively accelerating away from all other galaxies, and acceleration means non-inertia.This is why a true, absolute inertial frame is not feasible. I can quite easily come up with two frames that are inertial with respect to each other, but they are not absolutely inertial.

"Find a way to place a spacecraft outside the influences of gravity, magnetism, and inertia, supply the spacecraft with a form of propulsion which is capable of reaching and breaching the speed of light, and the craft will probably succeed with no ill effects."

By the sounds of it, you haven't quite grasped the basics of relativity. When you describe a body to be moving with some non-zero velocity, you imply a reference frame relative to which that object is moving - i.e. is not at rest. Within this reference frame, it is not possible for that body to reach the speed of light, because the faster that body moves the more energy is required to accelerate it further (its inertia increases). Note that energy (mass, kinetic, etc.) is also relative. The body itself (say, a ship with a passenger) will observe none of the predicted effects of relativity from itself, because in its frame of reference it is at rest - always.

So, again, I plead my case, and thank all for their input with due respect...but still am left with my original request: Prove me wrong. Please. If I'm wrong, I want to know why.

Prove what wrong? You have offered no formal theory to assess. You have an undeveloped idea that you think will supersede the works of many great, learned physicists, and by the sounds of it you will not accept any explanation as to why you're wrong. Look, I'm not trying to bum you out, but before trying to rewrite relativity, both special and general, why don't you study them first so you know what you're dealing with? Right now you're asking people whether a philosophically sound, experimentally verified and now universally accepted theory based on observed universal laws you don't fully understand but a lot of very clever people have worked very hard do is wrong, and your contradicting theory with no formulation, with no experimental evidence or any means to prove or disprove otherwise is right, but by an amazing coincidence comes out with the exact same results. You can believe whatever you want to believe and that's not necessarily a bad thing, but you're not really giving anyone anything to go on. I can ask you to prove I'm not 38 years old - you can't. That doesn't make it true.

 

[AgnosticPriest]

So, since in your simplistic view of physics inertia is undoubtedly an inherent property of matter, how, and more importantly WHY, should tests of relativity be done in its absence?

To rule it out as a cause, of course. Or to determine that it is the cause. Why test the speed of light in a vacuum? Because you don't want air interfering with the experiment. Same thing.

The effects of SR you describe, such as time dilation, were predicted by Einstein, previously unobserved, as a result of his theory based on two universal principals. Not only that, but it explained WHY those principals will always be true. Subsequent experimental evidence confirmed that Einstein's predictions were correct. That's far from 'it just is'. Give the guy some credit.

I'm giving the guy credit. How could he have possibly considered all the factors when he himself may have been unaware of them. He is only human after all. Just because somebody feels there is a flaw in someone else's theory doesn't mean the former is disrespecting the latter. Give ME some credit! I may not be a math genius, but I am Mensa material.

Prove what wrong? You have offered no formal theory to assess. You have an undeveloped idea that you think will supersede the works of many great, learned physicists, and by the sounds of it you will not accept any explanation as to why you're wrong. Look, I'm not trying to bum you out, but before trying to rewrite relativity, both special and general, why don't you study them first so you know what you're dealing with?

I have studied them. I believe I already covered that. I've read many different books on the subject and none of them--not even the ones which try to explain twin paradox--answer the questions I've been posing. My idea may seem undeveloped to you because I cannot express it mathematically. Perhaps the concept will continue to elude the scientific community until one with the mathematical aptitude can express cogently what I am trying to say.

I'm not refusing explanations. None have been given which take all that I have proposed into account. I'm not sticking my neck out and declaring Einstein an idiot. The reason I don't go public with this kind of debate is because I want physicists to tear it apart. All of you guys giving me input is keeping my brain working and polishing my concept.

But it is also reaffirming my theory. I know that it is impractical based on today's technological advances to even dream of experimenting with it, but nevertheless I do dream of it.

How can one experiment on the nature of anything when ones own environment effects the outcome? A pure experiment has no interference whatsoever, or it takes the interferences into account.

When you describe a body to be moving with some non-zero velocity, you imply a reference frame relative to which that object is moving - i.e. is not at rest. Within this reference frame, it is not possible for that body to reach the speed of light, because the faster that body moves the more energy is required to accelerate it further (its inertia increases).

You assume that all future advances in propulsion will have inertial effects on its passengers and craft. I'm reaching further than that. Let's pretend. We have a new propulsion which allows a traveler to achieve any speed instantaniously. We have a form of shielding which allows the traveler and his ship to push aside the effects of gravity and magnetism. The traveler is now in a pure void in space and his speed means nothing without something to compare it to. As far as physics is concerned he is standing still no matter what speed is achieved. Nothing outside his little bubble has any affect on him or his ship. The universe goes about its business as usual and he whips around it like a ghost, showing up wherever he desires.

I do not think that Einstein was wrong. I think he was practical. All things remaining as they are now, we will not be able to breach light speed. We'd be lucky to achieve it. As long as we are being manipulated by the effects of gravity, inertia, and magnetism, we are slaves to that fact. I want to find out if there is some special law which proves that it is NOT due to some outside influence. I want to know if that can be proven at all with today's technology. I am not trying to disqualify Einstein. I'm just wanting to show that one cannot go about declaring that a few tainted experiments turns a theory into a law and anyone with any ideas contrary to it shouldn't be ostracized.

There is room for speculation here. Not much room, granted. But it's there I think.

 

[Janus]

To rule it out as a cause, of course.

Been done.(Ruled out as a cause that is.)

 

[El Hombre Invisible]

I have studied them. I believe I already covered that. I've read many different books on the subject and none of them--not even the ones which try to explain twin paradox--answer the questions I've been posing. My idea may seem undeveloped to you because I cannot express it mathematically. Perhaps the concept will continue to elude the scientific community until one with the mathematical aptitude can express cogently what I am trying to say.

I'm not refusing explanations. None have been given which take all that I have proposed into account. I'm not sticking my neck out and declaring Einstein an idiot. The reason I don't go public with this kind of debate is because I want physicists to tear it apart. All of you guys giving me input is keeping my brain working and polishing my concept.

But it is also reaffirming my theory. I know that it is impractical based on today's technological advances to even dream of experimenting with it, but nevertheless I do dream of it.

How can one experiment on the nature of anything when ones own environment effects the outcome? A pure experiment has no interference whatsoever, or it takes the interferences into account.

I don't think I made my point clear, or else you did not follow it. The effects you're asking about were not observed until after Einstein developed his special theory. These phenomena were not the raison d'etre of the development of the theory - they were derived side-effects of a bigger issue.

While he consistently conceived of experiments to prove himself wrong, Einstein was not much of an experimentalist as far as I'm aware - he left that to others. Phenomena such as time dilation were predicted in inertial frames and concerning inertial objects. The fact that no absolute inertial frame exists doesn't matter - if one did, then we would expect those effects. Einstein then developed his theory to cover all frames, and those phenomena are still present.

So, your assertion that these previously unobserved phenomena that were discovered as side-effects of special relativity would not actually be present in inertial frames (should one exist) but only in gravitational and magnetic fields would not only mean Einstein was wrong (because these phenomena are a natural consequence of SR), but also that by a mind-bogglingly amazing coincidence the unheard of effects he predicted would turn out to be true for a completely different reason . This is not a case of Einstein failing to consider all factors - you're saying he arrived at the correct conclusions without any of the contributing factors .

 

[selfAdjoint]

To rule it out as a cause, of course. Or to determine that it is the cause. Why test the speed of light in a vacuum? Because you don't want air interfering with the experiment. Same thing.

That's ridiculous! Air is a removable environmental factor - and relativity has been tested in a high vacuum. Inertia is not removable from matter; it is a fundamental property of matter (in classical mechanics). You can't just factor it away. And testing relativity on the fictional "non-inertial" matter wouldn't mean anything for our physical world anyway.

 

[arildno]

AgnosticPriest:
It seems that you believe that a non-inertial frame is a frame in which there is no inertia.
Is that what you think?

 

[AgnosticPriest]

My reason for even bringing up a seemingly fictional state of travel (ie, travel without the effects of inertia) is because of studies into the possibility that inertia-less acceleration could one day be created. If there were a form of propulsion whereby all molecules in and on the vehicle (including its occupants) were simultaneously points of thrust, there would be no inertial effects and any speed could be reached instantaniously. Science fiction writers who are also theoretical physicists speculate that studies into gravity and electromagnetism may one day lead to such forms of travel.

This speculation has sparked many wonderful "hard" sci-fi novels, such as The Foundation Saga. It has also sparked my interest in such questions as "what is gravity" and "is light speed really the universe's speed limit". It just seems to me that, without the effects of inertia, without the interaction of any outside "stationary" object, and assuming one has the ability and power to reach and breach the speed of light, there should not be anything in the laws of physics that would deny one that ability.

All of this is, of course, speculation. The most intelligent physicist no more can prove the speed of light the universal speed limit than I can prove it isn't. My purpose for having posted this heretical blog was to get as much educated feedback from the physics community as I could on the subject.

I've studied a lot on the subject from both perspectives, but never have been able to have an open-minded and honest discussion with a PhD on the subject. Any further insights are welcome, and all posts thusfar are greatly appreciated.

 

[fargoth]

well, even if instant speed changes were possible, the kinetic energy of the system is inertia dependant... this is experimentally varrified.

the energy you have to give to body inorder for it to achieve a certain speed relative to you is the same no matter what's the time it took you to give it off to that body.
so a body can't go faster then light... the inertia goes to infinity as the speed goes to C.

i could build a perpetum mobile if i could make things go at relativistic speeds with less energy just because i made them get this speed instantly.

 

[Flatland]

With regard to all the Points, these were quoted from the theories/laws. They mean whatever the author meant.

In point 1, it seems quite clear that ANYTHING in motion can equally call its observer the one who is in motion. If this is true, we are all traveling light speed right now, relative to the photon's point of view. It's an impossible paradox!

actually, from a photon's point of view the universe is still a singularity, there is no such thing as traveling from a photon's perspective.