Is FTL actually possible?

[Genady]

Talking of wishful thinking that has been mentioned earlier in this thread. I don't see why we can accept inevitability of our personal death, while have a problem accepting inevitability of death of humanity. Or inevitability of our cosmic isolation until that happens. Perhaps, this question belongs to a thread in a different forum though.

[MJ kihara]

4 hours ago, swansont said:

Light travels at c, so it shows up as a 45 degree line (the null line). If you go slower it takes longer to go some distance x, so that will appear above (steeper). FTL would go below. Both cases are depicted - one for the FTL signal, one for the STL ship.

If you didn’t move it would show up as a vertical line - motion through time but not space

FTL would go below...As u move towards space axis it becomes FTL,then FTL,then FTL...that's you are still 'on' space axis as you move infinitely towards it....once 'in' it movement becomes instantaneous (inside the space
axis)

3 hours ago, Genady said:

A transmission that is instantaneous in the ship frame goes parallel to the ship's space axis

 

2 hours ago, Genady said:

Any instant transmission in one frame violates causality in other frame. There is no physical difference between frames.

When the frames themselves are conscious....they will know/are aware what is happening and no causality violation...or it simply doesn't exist to them.

2 hours ago, Genady said:

Talking of wishful thinking that has been mentioned earlier in this thread. I don't see why we can accept inevitability of our personal death, while have a problem accepting inevitability of death of humanity.

There is still hope to the contrary...based on reexaming of basic framework of the universe....mmm that concept of consciousness-emptiness as the fundamental it allows FTL and FFTL(faster and further than light speed)...I know u will tell me that's not science but it reproduces scientific concepts perfectly well..if so if it's not science I don't know what it is.

On 4/14/2023 at 6:33 PM, zapatos said:

I'm only going on what Einstein said: "Space-time does not claim existence in its own right, but only as a structural quality of the [gravitational] field".

 

That's correct.

But spacetime fabric claim existence in it's own right(-not the rubber thing or floor mat analogy-...in this case fabric made up of spacetime particles ('virtual particles') whose fundamental constituent is consciousness and Emptiness).

I expect a lot of thumb downs esp from people who don't comprehend it and those who have been bound to reason within being born and dying.

[Moontanman]

6 hours ago, Genady said:

Any instant transmission in one frame violates causality in other frame. There is no physical difference between frames.

 

5 hours ago, swansont said:

It would violate it just as explained in the video. Instantaneous is just the most extreme case of FTL.

In the video it shows as it's first example that an instantaneous signal does not violate causality... I've watched it over and over, he does say this and shows it by moving through the diagram to show that from the stand point of all three, the supernova, earth and vega that causality is not violated. I'll watch it yet again. I can't understand why only I am seeing this.  

In the cool worlds video starting at 10:45 to 13:40 only after he puts a STL ship on the diagram does causality violations show up. To me it seems that the STL ship sending a FTL message back to Earth causes the problem. If the STL ship couldn't send the message then causality would not be violated except the STL ship would be confused by the message if it could receive it. But if the STL ship could nether send or receive the FTL signal the causality would be preserved from from everyone's point of view.

Vega might receive the message before it could see the light but this info wouldn't be able to cause a time loop unless vega could send a signal to before the earth saw the nova. Am i making any sense here or am i just totally off the rails? The time paradox could be avoided by the moving ship not being able to send a FTL signal and would be totally avoided if the STL ship couldn't receive a FTL signal either. I see how this is contrived but the fact is can be contrived to not violate causality seems to indicate the FTL signal could be sent and received just not by small moving objects. 

All of a sudden I do see the problem and where I made my mistake but it doesn't seem completely impossible to send an FTL message and the size and maybe mass of the object sending the signal are at the crux of the issue.  I guess i am too much of an optimist to think this is impossible but the circumstances do seem to need to be rather "special".  

Edited April 17, 2023 by Moontanman

[Genady]

4 hours ago, Moontanman said:

To me it seems that the STL ship sending a FTL message back to Earth causes the problem. If the STL ship couldn't send the message then causality would not be violated

The "ship" can be just another planet with people on it. Then causality is violated.

Edited April 17, 2023 by Genady

[swansont]

5 hours ago, Moontanman said:

In the video it shows as it's first example that an instantaneous signal does not violate causality... I've watched it over and over, he does say this and shows it by moving through the diagram to show that from the stand point of all three, the supernova, earth and vega that causality is not violated. I'll watch it yet again. I can't understand why only I am seeing this.

The FTL signal doesn’t violate causality for the sender and receiver. The violation appears when you add the moving observer.

[Genady]

9 hours ago, MJ kihara said:

When the frames themselves are conscious....they will know/are aware what is happening and no causality violation...or it simply doesn't exist to them.

The causality violation does not happen to frames. It happens to observers.

 

9 hours ago, MJ kihara said:

that concept of consciousness-emptiness as the fundamental it allows FTL

It does not prevent causality violation.

[MigL]

I have mentioned this many times in the past; frames of reference are very important in relativity.
Considering an event from the wrong frame usually yields nonsense, and has led to much confusion in past threads.

Leaving aside the fact that a FtL ship is already capable of violating causality, it may, in fact, be possible for a FtL ship to send a FtL message without violating causality, but only in the frame of that FtL ship.
That doesn't change the fact that it will violate causality for every other timelike observer who is not in that particular frame.

That is also what a space-time diagram does, Moon.
It separates the timelike ( where events are separated by an interval which allows for causal connection) from the spacelike ( FtL domain where events cannot affect other events ) by the lightlike line ( the SoL ).
A 3dimensional representation would be a light cone.

[mistermack]

32 minutes ago, MigL said:

I have mentioned this many times in the past; frames of reference are very important in relativity.
Considering an event from the wrong frame usually yields nonsense, and has led to much confusion in past threads.

If you take the current state of knowledge as correct, that no physical object can exceed the speed of light in an inertial frame, does that mean that the scope and extent of intertial frames is limited? 

For example, if you take me as your object, then no frame in which I am moving at more than c can be a real and possible frame ? Would that be a fair conclusion? 

[Moontanman]

Thanks guys, I think i see where my mind went wrong, thanks again. 

[swansont]

To add to MigL’s comment - it’s an established approach to look for violation of energy or momentum in a chosen frame, because if you find a violation one frame, it’s game over. SR tells us the the laws of physics have to work the same in all frames.

[StarEagle1]

I'm not a scientist, but this is so interesting I'd like to throw in a couple of speculative thoughts. If someday we could actually fly at (near) light speed, then maybe it would be easier to take the next step to FTL. Okay, hypothetically could the particles of a solid object, that are already traveling, be so energized with a strong electromagnetic field that they could then travel at a velocity of near light speed? And, if there were two objects attached to each other, would they fuse together in such a strong magnetic field? If you haven't guessed already, I'm thinking about a ship that some say disappeared, and then reappeared many miles from where it started, within a very short time.

 

[Genady]

1 hour ago, StarEagle1 said:

If someday we could actually fly at (near) light speed, then maybe it would be easier to take the next step to FTL.

To the contrary, it will be rather harder.

[StarEagle1]

I should not have made that statement in that way, sorry.

You may be correct, it might be better to try as soon as it seems possible.

 

Edited April 20, 2023 by StarEagle1

[geordief]

I thought we were already flying at light speed if we choose  the appropriate  frame     of reference.

Is the actual  barrier that of attaining light speed wrt a frame of reference  that we are initially  at rest with?

 

Ie accelerating to light speed from  and wrt an initial frame of reference?

[Genady]

1 hour ago, geordief said:

we were already flying at light speed if we choose  the appropriate  frame     of reference.

What do you mean?

[zapatos]

5 minutes ago, Genady said:

What do you mean?

Aren't we moving at near light speed if we choose the reference frame of a neutrino for instance?

[Genady]

3 minutes ago, zapatos said:

Aren't we moving at near light speed if we choose the reference frame of a neutrino for instance?

Yes, of course we are.

[zapatos]

4 minutes ago, Genady said:

Yes, of course we are.

So to @geordief's point, why is so difficult to move at c wrt the neutrino? If a neutrino moves at 99.99999999 of c, are we unable to move in the opposite direction at 0.00000001 of c? Or no matter how fast we move, will it always appear to us in our frame, that we never manage a relative speed of c?

[Genady]

If a neutrino moves at 0.99c in lab frame and we move in opposite direction at 0.01c in lab frame, then we move at 0.9902c in neutrino frame.

Edited April 20, 2023 by Genady
c

[geordief]

30 minutes ago, Genady said:

What do you mean?

I meant it the same way as  @zapatos clarified  it.If we find or choose  a suitable  reference point, we are moving wrt it at a near light speed(the neutrino was a good example)

With most objects we only move at slow speeds but  ,with the example of the neutrino  not only can we say that the neutrino  is moving at near light  speed  wrt to us but we can also say that   in the frame of the neutrino  we are moving at a near light speed wrt it.

 

So in that sense we are moving at a near light speed even though we think we are not moving (I know you know this  of course)

 

 

[Genady]

11 minutes ago, geordief said:

I meant it the same way as  @zapatos clarified  it.If we find or choose  a suitable  reference point, we are moving wrt it at a near light speed(the neutrino was a good example)

With most objects we only move at slow speeds but  ,with the example of the neutrino  not only can we say that the neutrino  is moving at near light  speed  wrt to us but we can also say that   in the frame of the neutrino  we are moving at a near light speed wrt it.

 

So in that sense we are moving at a near light speed even though we think we are not moving (I know you know this  of course)

 

 

Alright, this is clear. What is the question?

[geordief]

19 minutes ago, Genady said:

Alright, this is clear. What is the question?

Not a question  but I was addressing @StarEagle1 's idea that " If someday we could actually fly at (near) light speed,"  to point out that we already did this.

 

I then asked " 

Is the actual  barrier that of attaining light speed wrt a frame of reference  that we are initially  at rest with?

 

ie accelerating to light speed from  and wrt an initial frame of reference..."

Edited April 20, 2023 by geordief

[Genady]

10 minutes ago, geordief said:

Not a question  but I was addressing @StarEagle1 's idea that " If someday we could actually fly at (near) light speed,"  to point out that we already did this.

 

I then asked " 

Is the actual  barrier that of attaining light speed wrt a frame of reference  that we are initially  at rest with?

 

ie accelerating to light speed from  and wrt an initial frame of reference..."

Ah, I didn't realize that you refer to that post...

No, the barrier is independent of the frame. In any frame, the faster you move the more difficult it is to add speed.

[geordief]

21 minutes ago, Genady said:

Ah, I didn't realize that you refer to that post...

No, the barrier is independent of the frame. In any frame, the faster you move the more difficult it is to add speed.

I accept that

 

I sometimes have the idea that if we have a system with mass and we convert its mass progressively  and in a directed manner to energy so that it accelerates in a particular  direction until the very last amount of mass in the system  is converted to energy...

if we make that system arbitrarily as large as  say half the (observable?) universe  would that give a mathematical  equation that would show that the final speed was a limit that was the same as c?

(yes I am thinking of a  theoretical nuclear rocket half the size of the universe that burns itself up as fuel)

Edited April 20, 2023 by geordief

[Genady]

15 minutes ago, geordief said:

I accept that

 

I sometimes have the idea that if we have a system with mass and we convert its mass progressively  and in a directed manner to energy so that it accelerates in a particular  direction until the very last amount of mass in the system  is converted to energy...

if we make that system arbitrarily as large as  say half the (observable?) universe  would that give a mathematical  equation that would show that the final speed was a limit that was the same as c?

(yes I am thinking of a  theoretical nuclear rocket half the size of the universe that burns itself up as fuel)

I don't think you need an equation for this. If you convert the entire mass to something massless, like e.g., light, then that something moves with the speed of light. Regardless of the initial mass.