Why we can never travel faster than the speed of light

[sjastro]

So, the implication that I was hoping someone would pick up on, is, supposing observers A and B are aware of their impending doom, how fast should A consider B to be going relative to himself? (And likewise, B concerning A's speed...)

Sorry but I performed badly at mind reading 101 but despite this serious impediment I still answered your question.

The observer at C on the ground is measuring the approach speed of A relative to B and vice versa as 0.88c.
At relativistic speeds Galilean relativity does not hold and the approach speed is not the sum of A and B's speeds 0.6c + 0.6c =1.2c.
This is because observers cannot exceed the speed of light and all observers such as A, B and C in this case will measure the speed of light as being c in their respective frames of reference.

 

[Neogaia777]

The discussion from what I recall is how does the momentum p of an object changes as the velocity reaches relativistic speeds.
At low speeds the momentum is p = mv but as the speed increases to relativistic magnitudes

p = mv/√(1-v²/c²)

Does the mass M increase relativistically M = mv/√(1-v²/c²), or does the velocity V increase V = v/√(1-v²/c²)?

Mathematically both variations are valid but since mass and charge are properties of an object and charge remains invariant (does not increase with increasing velocity), the modern day preference is for the mass M to remain invariant as well.

It's about the frame of reference, an observer on earth will measure the clock on a spaceship running slower compared to his own clock.
The reason why your GPS works is that atomic clocks on GPS satellites need to be adjusted to take into consideration gravitational time dilation effects of general relativity and velocity effects of special relativity to remain synchronized with atomic clocks on Earth.


It doesn’t work that way.
From a classical physics perspective to accelerate an object of mass m from rest to some velocity v, work W needs to be performed on the object and equals the change in KE (kinetic energy) in this case W = (1/2)mv².

At relativistic speeds however the change in KE = mc²/√(1-v²/c²) - mc² where mc² is the rest energy.
If v = c the mc²/√(1-v²/c²) term becomes infinitely large irrespective of the value of constant acceleration.

It doesn't matter what the magnitude of the constant acceleration is, eventually the speed of light is reached which requires an infinite amount of energy.
Particle accelerators are examples of this limitation, its no coincidence the LHC accelerates protons to 99.999999% the speed of light.
There is a law of diminishing returns as increasing the particle accelerator centre of mass energies does not produce significant increases in particle velocities as the speed of light is the limit.

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All of the above.

Special relativity handles time dilation for objects moving at constant velocities and general relativity for objects being accelerated under the influence of gravity and curved spacetimes.
In the case of an object undergoing a constant proper acceleration in flat space time, special relativity is extended and time dilation is explained using Rindler coordinates and for circular motion Born coordinates.

I appreciate you bearing with me. But what exactly is preventing us from causing a particle/object to go at speeds beyond c again?

You mentioned energy, and we agreed it is not the mass, but what kind of energy are we talking about here? The energy inside the atom or particle becoming unstable? Or becoming heavier maybe? Or do you maybe mean the energy required to push it maybe? Or just what exactly?

I'm trying to get over the fact that if an atom or particle doesn't approach infinite mass, then what is preventing us from just being able to keep pushing it, etc?

And we talked about the time dilation effect on that object or particle? Is it not true that the rate at which time flows for that object (or particle) slows for it (but only it) when it is either; in motion maybe?, or maybe while it is being accelerated and G's are being created or applied maybe? (I don't know which one of those it is right now currently, etc).

But could you maybe just tell me just very shortly, and with just a few words maybe, and without a whole lot of math maybe, (although I do appreciate the mathematical explanations, but I'm right now not very skilled at all with math yet, but hoping that will change sometime soon, as I plan on studying it a lot more pretty soon, even if I have to take some classes on it, etc, but right now though, pretty much a foreign language to me right now currently, etc).

Anyway, but if you could maybe, with just a few words, and trying to use mostly only just words maybe, can you maybe try to answer or tell me just what it is exactly that is preventing us from just continuing to push an object (or atom) (or particle) to at or beyond c maybe?

Much thanks for putting up with me.

Take Care/God Bless.

 

[Hans Blaster]

I appreciate you bearing with me. But what exactly is preventing us from causing a particle/object to go at speeds beyond c again?

You mentioned energy, and we agreed it is not the mass, but what kind of energy are we talking about here? The energy inside the atom or particle becoming unstable? Or becoming heavier maybe? Or do you maybe mean the energy required to push it maybe? Or just what exactly?

I'm trying to get over the fact that if an atom or particle doesn't approach infinite mass, then what is preventing us from just being able to keep pushing it, etc?

And we talked about the time dilation effect on that object or particle? Is it not true that the rate at which time flows for that object (or particle) slows for it (but only it) when it is either; in motion maybe?, or maybe while it is being accelerated and G's are being created or applied maybe? (I don't know which one of those it is right now currently, etc).

But could you maybe just tell me just very shortly, and with just a few words maybe, and without a whole lot of math maybe, (although I do appreciate the mathematical explanations, but I'm right now not very skilled at all with math yet, but hoping that will change sometime soon, as I plan on studying it a lot more pretty soon, even if I have to take some classes on it, etc, but right now though, pretty much a foreign language to me right now currently, etc).

Anyway, but if you could maybe, with just a few words, and trying to use mostly only just words maybe, can you maybe try to answer or tell me just what it is exactly that is preventing us from just continuing to push an object (or atom) (or particle) to at or beyond c maybe?

Much thanks for putting up with me.

Take Care/God Bless.

If you start with any particle with mass at a subluminal velocity, as you apply a force to it, F, it will change the momentum, p, (F = dp/dt). The momentum, p = Wmv (I use W for the relativist factor usually written as gamma, p = mv/√(1-v²/c²), W = √(1-v²/c²) ) can be come arbitrarily large while v < c. As the relativistic momentum gets larger and larger, v never makes it to c, and the particle remains slower than light.

 

[SelfSim]

I appreciate you bearing with me. But what exactly is preventing us from causing a particle/object to go at speeds beyond c again?
You mentioned energy, and we agreed it is not the mass, but what kind of energy are we talking about here? The energy inside the atom or particle becoming unstable? Or becoming heavier maybe? Or do you maybe mean the energy required to push it maybe? Or just what exactly?

I'm trying to get over the fact that if an atom or particle doesn't approach infinite mass, then what is preventing us from just being able to keep pushing it, etc?

I don't get why you don't get this ..(?)
@sjastro already explained this in the simplest way possible:

.. eventually the speed of light is reached which requires an infinite amount of energy.

What type of energy doesn't matter.
Do you know how to generate an infinite amount of energy?

 

[Neogaia777]

If you start with any particle with mass at a subluminal velocity, as you apply a force to it, F, it will change the momentum, p, (F = dp/dt). The momentum, p = Wmv (I use W for the relativist factor usually written as gamma, p = mv/√(1-v²/c²), W = √(1-v²/c²) ) can be come arbitrarily large while v < c. As the relativistic momentum gets larger and larger, v never makes it to c, and the particle remains slower than light.

Momentum, for that object, is just speed though, correct? So why can not that object be pushed to or beyond c? (Theoretically, etc) (Because just exactly how we might do that right now may seem to be impossible to or for us right now currently, etc).

 

[Neogaia777]

I don't get why you don't get this ..(?)
@sjastro already explained this in the simplest way possible:

What type of energy doesn't matter.
Do you know how to generate an infinite amount of energy?

Ok, "requires an infinite amount of energy", etc. Well, just forgive me then for just simply trying to ask "to do what", etc?

 

[SelfSim]

Well, just forgive me then for just simply trying to ask "to do what", etc?

I really don't understand your question there .. what do you mean?
(Or was it just unnecessary snark or something? Was it intended as a 'Poe' type of question?)

 

[Neogaia777]

I really don't understand your question there .. what do you mean?
(Or was it just unnecessary snark or something? Was it intended as a 'Poe' type of question?)

No, not at all, I'm just simply trying to understand what is to be understood about "infinite energy"?

And I'm also not talking about in any of these questions about it's relativity to anything else either, but just for it only, etc.

Take Care.

 

[Neogaia777]

No, not at all, I'm just simply trying to understand what is to be understood about "infinite energy"?

@SelfSim

For example, in post #23, I asked if he meant the energy within the objects or particles becoming unstable (or infinite), or them becoming heavier somehow maybe, or if he maybe meant the energy required to push it or continue pushing it, or things like that, or else just what exactly, etc?

They are just some honest questions, etc. No snarkiness or deception meant here at all, etc.

Take Care.

 

[timewerx]

I`m sorry to say, maybe it`s just not possible.

It's not possible to travel faster than light in space....

But space is not stationary. Space can move and gain velocity. If the local space is already moving at the speed of light then theoretically, the light within it can travel at 2x lightspeed or "2c" in terms of absolute velocity.

 

[Neogaia777]

It's not possible to travel faster than light in space....

Why, or why not?

But space is not stationary. Space can move and gain velocity. If the local space is already moving at the speed of light then theoretically, the light within it can travel at 2x lightspeed or "2c" in terms of absolute velocity.

The only place space appears to moving out away from us (as the center) near or at or beyond the speed of light, is near or at the edge of observable space, and beyond it, which has to be very, very far away, but other than that, near the edge of a very large gravity well, and once you cross the edge of that gravity well, as you are going towards the center of it, once you cross it, etc, space could be said to be quote/unquote "moving" at or beyond the speed of light maybe, etc?

But in reality it is just such a great depression in space that nobody really knows what is really happening once you go beyond it really, etc. But we know it's like a well, or hole, or very, very deep, powerful "pit" really, from which we right now think nothing can escape really, etc, and we don't know what happens to what goes in it when it does right now currently either, because it right now defies currently known physics right now currently, etc.

But if you could create a depression in the space ahead of you, and maybe also an expansion of space behind you maybe, then this could theoretically be a way you could move a ship or object through space at maybe speeds beyond the speed of light maybe? But I don't think we right now have or know of any kind of technology that can do this right now currently though, etc.

In reality space doesn't "move", but it's just changed or affected by different gravitational forces all over the place, etc. And the effects are usually minor in most cases unless it's something like a black hole really, etc. And you have to be relatively close to one for it to begin to affect space (or light) (or time) dramatically, etc.

God Bless.

 

[sjastro]

@SelfSim

For example, in post #23, I asked if he meant the energy within the objects or particles becoming unstable (or infinite), or them becoming heavier somehow maybe, or if he maybe meant the energy required to push it or continue pushing it, or things like that, or else just what exactly, etc?

They are just some honest questions, etc. No snarkiness or deception meant here at all, etc.

Take Care.

Let’s start by looking at a simple example involving classical physics where one doesn’t have to worry about mass increasing, pushing a stationary block of stone of mass m up to some velocity v.
To overcome the inertia you need to make an effort to set the block in motion, this effort is work being done on the block and equals the change in KE (kinetic energy).

Work = (½)mv² - (½)m0² = (½)mv²

If we wanted double the velocity,

Work = (½)m(2v)² - (½)m0² = (½)4mv².

Hence to double the velocity requires a 4X increase in KE.

Now let’s extend this idea to special relativity.
The work energy equation is somewhat more complicated as we now have to consider the block of stone has energy even at rest according to Einstein’s famous E = mc².
To push the block of stone up to relativistic speeds v,

Work = mc²/√(1-v²/c²) - mc²

Let’s look at the first term where the block of stone is at some velocity v.
As v gets larger the term mc²/√(1-v²/c²) gets larger as well.
When v = c, (1-v²/c²) = 0 and we get the dreaded division by zero.
The physical interpretation of this result is the change in KE becomes infinitely large when pushing the block of stone from rest up to the speed of light.

Note this has been done by considering speed only and the mass has remained constant or invariant throughout.

 

[Neogaia777]

Let’s start by looking at a simple example involving classical physics where one doesn’t have to worry about mass increasing, pushing a stationary block of stone of mass m up to some velocity v.
To overcome the inertia you need to make an effort to set the block in motion, this effort is work being done on the block and equals the change in KE (kinetic energy).

Work = (½)mv² - (½)m0² = (½)mv²

If we wanted double the velocity,

Work = (½)m(2v)² - (½)m0² = (½)4mv².

Hence to double the velocity requires a 4X increase in KE.

Now let’s extend this idea to special relativity.
The work energy equation is somewhat more complicated as we now have to consider the block of stone has energy even at rest according to Einstein’s famous E = mc².
To push the block of stone up to relativistic speeds v,

Work = mc²/√(1-v²/c²) - mc²

Let’s look at the first term where the block of stone is at some velocity v.
As v gets larger the term mc²/√(1-v²/c²) gets larger as well.
When v = c, (1-v²/c²) = 0 and we get the dreaded division by zero.
The physical interpretation of this result is the change in KE becomes infinitely large when pushing the block of stone from rest up to the speed of light.

Note this has been done by considering speed only and the mass has remained constant or invariant throughout.

Thank you very much @sjastro, I really do appreciate you, just so you know that, ok.

But what I'm right now not understanding is why it takes 4 times more work, or force, to only double an objects velocity?

But understanding why it always takes more and more work, or force, to the point of approaching infinity, and maybe why, could really, really help me in understanding this right now currently?

Much thanks.

Take Care/God Bless.

 

[Neogaia777]

Let’s start by looking at a simple example involving classical physics where one doesn’t have to worry about mass increasing, pushing a stationary block of stone of mass m up to some velocity v.
To overcome the inertia you need to make an effort to set the block in motion, this effort is work being done on the block and equals the change in KE (kinetic energy).

Work = (½)mv² - (½)m0² = (½)mv²

If we wanted double the velocity,

Work = (½)m(2v)² - (½)m0² = (½)4mv².

Hence to double the velocity requires a 4X increase in KE.

Now let’s extend this idea to special relativity.
The work energy equation is somewhat more complicated as we now have to consider the block of stone has energy even at rest according to Einstein’s famous E = mc².
To push the block of stone up to relativistic speeds v,

Work = mc²/√(1-v²/c²) - mc²

Let’s look at the first term where the block of stone is at some velocity v.
As v gets larger the term mc²/√(1-v²/c²) gets larger as well.
When v = c, (1-v²/c²) = 0 and we get the dreaded division by zero.
The physical interpretation of this result is the change in KE becomes infinitely large when pushing the block of stone from rest up to the speed of light.

Note this has been done by considering speed only and the mass has remained constant or invariant throughout.

Thank you very much @sjastro, I really do appreciate you, just so you know that, ok.

But what I'm right now not understanding is why it takes 4 times more work, or force, to only double an objects velocity?

But understanding why it always takes more and more work, or force, to the point of approaching infinity, and maybe why, could really, really help me in understanding this right now currently?

Much thanks.

Take Care/God Bless.

@sjastro

And we're doing this in space, right? Are you maybe suggesting that there is some kind of drag or resistance in space maybe?

Isn't it when we push an object in space, that it will just keep going if we stop pushing it? So, why then does it take more and more force/work/energy to accelerate it, to be being applied to the object constantly up to the point of infinity as it approaches c to continue to be accelerating it at a constant rate?

Thank you again. I know you are trying to be simple, and I really do appreciate it, ok.

Take Care/God Bless.

 

[timewerx]

Why, or why not?

The only place space appears to moving out away from us (as the center) near or at or beyond the speed of light, is near or at the edge of observable space, and beyond it, which has to be very, very far away, but other than that, near the edge of a very large gravity well, and once you cross the edge of that gravity well, as you are going towards the center of it, once you cross it, etc, space could be said to be quote/unquote "moving" at or beyond the speed of light maybe, etc?

But in reality it is just such a great depression in space that nobody really knows what is really happening once you go beyond it really, etc. But we know it's like a well, or hole, or very, very deep, powerful "pit" really, from which we right now think nothing can escape really, etc, and we don't know what happens to what goes in it when it does right now currently either, because it right now defies currently known physics right now currently, etc.

But if you could create a depression in the space ahead of you, and maybe also an expansion of space behind you maybe, then this could theoretically be a way you could move a ship or object through space at maybe speeds beyond the speed of light maybe? But I don't think we right now have or know of any kind of technology that can do this right now currently though, etc.

In reality space doesn't "move", but it's just changed or affected by different gravitational forces all over the place, etc. And the effects are usually minor in most cases unless it's something like a black hole really, etc. And you have to be relatively close to one for it to begin to affect space (or light) (or time) dramatically, etc.

God Bless.

It's a start. Massive objects in space can move the space with them. Galactic clusters could to a very significant degree. And theoretically, they can travel faster than light to a significant factor.

The only problem is we don't have a means to if a far red-shifted galaxy is already traveling faster-than-light if they show up in our radio telescopes at all. We don't have a precedent for this. The photon may be polarized by transit between moving spaces. But how it's going to be polarized I have no idea. Maybe our math and physics geniuses can figure this out. Once we figure out the polarization degree, we can start looking for it.

I think the key to figuring out the warp drive technology are the right questions and an AI that can answer those questions. As ridiculous as it sounds, I think we'll have that capability with AI very soon. And I think we could have the world's first warp drive within 10 years (developed with AI and AI undergoing parallel development as well) IF that is actually in anyone's goals who have the resources to make it happen. But as it goes today, everyone is still hung up with rockets, ion drives, nuclear reactor drives - classical Newtonian propulsion systems and using AI to manipulate social media.

 

[Neogaia777]

It's a start. Massive objects in space can move the space with them. Galactic clusters could to a very significant degree.

I think what they really do is create depressions in space, due to their gravity, while areas with less gravity, or that are possibly being expanded by other forces, push out upon them, or around them maybe, etc. But I don't think space itself is moving, but is just being depressed or folded/bent, and/or expanded in certain areas, and this has an effect on anything with mass in the universe maybe, etc. "Maybe", etc.

And theoretically, they can travel faster than light to a significant factor.

Again, I don't think space actually moves, but is just being compressed or expanded in certain areas maybe, which has an effect on anything with mass in the universe, etc. But then again, gravitational forces can also affect photons, or light, which doesn't have mass, so "who knows", etc. But I don't think space itself actually travels, or moves faster than light, etc. And I don't even believe this for objects/space that is at or beyond the edge of the observable universe either, because I think that is an illusion, or is a perspective or point of view that depends upon where you are at or are located in the universe, etc.

The only problem is we don't have a means to if a far red-shifted galaxy is already traveling faster-than-light if they show up in our radio telescopes at all. We don't have a precedent for this. The photon may be polarized by transit between moving spaces. But how it's going to be polarized I have no idea. Maybe our math and physics geniuses can figure this out. Once we figure out the polarization degree, we can start looking for it.

You are just a little bit out of my normal areas of expertise or pools I right now regularly currently play in with this one right now, so I'll just say I hope they can too...

I think the key to figuring out the warp drive technology are the right questions and an AI that can answer those questions. As ridiculous as it sounds, I think we'll have that capability with AI very soon. And I think we could have the world's first warp drive within 10 years (developed with AI and AI undergoing parallel development as well) IF that is actually in anyone's goals who have the resources to make it happen. But as it goes today, everyone is still hung up with rockets, ion drives, nuclear reactor drives - classical Newtonian propulsion systems and using AI to manipulate social media.

I will just say that I agree with you that AI, and the continuing development of it, could possibly hold the keys to changing a lot of things with or about our future in the future, etc.

God Bless.

 

[timewerx]

Again, I don't think space actually moves

Based on General Relativity and actual evidence for "frame dragging" ("local space" or "space - time" moved or "dragged" by objects with mass) is well established:

frame-dragging « Einstein-Online

www.einstein-online.info

https://einstein.stanford.edu/content/education/lithos/litho-fd.pdf

Mass curves space time but most people don't know if the mass is moving, it drags space along with it as well. The effect is incredibly miniscule for with everyday objects we encounter. But for extremely dense and extremely massive objects like neutron stars, the effect will be significant and spectacularly noticeable.

Theory of General Relativity also accounts for "linear dragging" for objects moving in a straight line but gathering evidence for it is much harder compared to spinning examples.

 

[Mark Quayle]

Guttairc said:
Modern nonsense, you take the idea that you can`t really measure speed because the observer is moving also. It`s the same nonsense as when they try to explain what gravity is, but it`s just things falling to the ground because there`s nothing interfering

Not in the slightest! My intuitive thought is that A approaches B, (or B approaches A), a 1.2 times the speed of light. The notion that there is no such thing as moving "faster than light" just doesn't make sense to me, seeing as how, (to me, of course), it's a question of the point of view from which the measurement is made.

If what is meant by "faster than light" refers only to whether A or B or C can never exceed the speed of light relative to their starting point, then that's another question, or, even if the question is whether they can exceed the speed of light relative to any one [moving] position from where they are at any one time, then ok. But that's not what I'm asking.

Implied in my question, I think, is the notion that what I have heard is axiomatic --that when [organized] matter reaches the speed of light, it becomes disorganized light (i.e. that can never be returned to the same organized state (rock, person, etc) that it was originally-- to me also makes no sense. While it may be accurate to say that A (changing the numbers to .5c) at, what from B's POV is the speed of light, A may appear as light, but from A's POV he is no less organized than when he started out.

Approaching such speeds, also, I suppose, the notion that one becomes "stretched out" relative to any one point along the way, also should apply to someone getting sucked into a black hole. I should think that one entering the event horizon should notice no change other than an irreversible direction of travel. He may even see himself in a situation where he is always further entering that event horizon, or some such thing, but while we would consider him stretched, I don't see how he would actually be breaking apart from stresses.

 

[Lost4words]

I can prove travel being faster than light....

Just watch Burt, next doors cat go when he sees Harry the rottweiler!!!

 

[AV1611VET]

I can prove travel being faster than light....

Just watch Burt, next doors cat go when he sees Harry the rottweiler!!!

Don't forget Snoopy!