Is FTL actually possible?

[Moontanman]

I thought I had a pretty good grip on why FTL was impossible. I was knowledgeable enough to at least think I understood why FTL was impossible even in the face of things like warp drive and worm holes. I was pretty confident that the time travel aspects would prohibit FTL even if the infinite energy requirements didn't.

Now I see one of my most respected scientific sources seemingly asserting that all I've been taught was solid as a rock is in fact on shaky ground at best, Sabine Hossenfelder has blown my mind by suggesting all I know might not be as solid as I was led to believe. Is anyone willing to watch this video and assure me that Sabine has slipped a cog so I can let go of the nearest pine tree and return to the idea of solid ground being solid ground?     

 

[TheVat]

Have never seen Sabine slip a cog.  Clean that pine tar off your hands.  Does she have a blog segment on this?  I can't watch video atm.

[swansont]

!

Moderator Note

We need a summary of the argument. From rule 2.7:

Videos and pictures should be accompanied by enough text to set the tone for the discussion

 

Is the argument that you can have v>c solutions in the relativity equations, as long as some other term is imaginary or negative (that is normally positive and real)?

[TheVat]

http://backreaction.blogspot.com/2015/06/does-faster-than-light-travel-lead-to.html

 

...The relevant point to take away from this is that superluminal travel in and by itself is not inconsistent. Leaving aside the stability problems with superluminal particles, they do not lead to causal paradoxa. What leads to causal paradoxa is allowing travel against the arrow of time which we, for better or worse, experience. This means that superluminal travel is possible in principle, even though travel backwards in time is not.

That travel faster than light is not prevented by the existing laws of nature doesn’t mean of course that it’s possible. There is also still the minor problem that nobody has the faintest clue how to do it... Maybe it’s easier to wait for the aliens to come visit us.

[Moontanman]

1 hour ago, TheVat said:

Have never seen Sabine slip a cog.  Clean that pine tar off your hands.  Does she have a blog segment on this?  I can't watch video atm.

I know what you mean, I watched it a couple times and I couldn't quite figure out what she was saying, I looked for a link but no joy. 

1 hour ago, swansont said:

!

Moderator Note

We need a summary of the argument. From rule 2.7:

Videos and pictures should be accompanied by enough text to set the tone for the discussion

 

Is the argument that you can have v>c solutions in the relativity equations, as long as some other term is imaginary or negative (that is normally positive and real)?

As far as I could tell no, the only thing I didn't quite get was something she called the "co-moving frame" or something similar, it was about the average rest state of the local universe. 

To be honest I thought I did accompany the video with enough text to set the tone for discussion. If it has been any source other than Sabine I would not have posted their video. She is one of a handful of youtubers that meet the criteria of real science done right. In other words she really is the scientist she claims to be. (she sings as well) She says something about this being connected to quantum gravity. The disconnect I am having a problem with starts at 16:00 and ends at 21:54. 

BTW does this rule also apply to written reports that do not rely on videos or pictures? 

[swansont]

3 minutes ago, Moontanman said:

BTW does this rule also apply to written reports that do not rely on videos or pictures? 

It’s in the guidelines: rule 2.7

23 minutes ago, Moontanman said:

To be honest I thought I did accompany the video with enough text to set the tone for discussion

You have to be able to discuss the topic without watching the video. “Explain what they said” requires that you watch the video.

1 hour ago, TheVat said:

http://backreaction.blogspot.com/2015/06/does-faster-than-light-travel-lead-to.html

 

...The relevant point to take away from this is that superluminal travel in and by itself is not inconsistent. Leaving aside the stability problems with superluminal particles, they do not lead to causal paradoxa. What leads to causal paradoxa is allowing travel against the arrow of time which we, for better or worse, experience. This means that superluminal travel is possible in principle, even though travel backwards in time is not.

That travel faster than light is not prevented by the existing laws of nature doesn’t mean of course that it’s possible. There is also still the minor problem that nobody has the faintest clue how to do it... Maybe it’s easier to wait for the aliens to come visit us.

IOW, She’s arguing against one of the objections to FTL, that of causality. She acknowledges that nothing traveling slower than c can be accelerated to be faster than c. 

[MigL]

She makes two arguments, both based on Special Relativity.
The first is that the energy required to accelerate a massive object to the speed of light is arguably not infinite.
When v=c in the equation, the expression becomes singular.
IOW, no longer valid Physics, just like anywhere else infinities arise.
( alsoexplains how mass is mostly binding energy, and the workings of the Higgs field )

The second, also using SR, using FTL travel, or communication, to send information elsewhere, then back to yourself in the past and violate causality, seems to disappear when GR is considered, as the co-moving frame estabilishes an entropic direction to the future and makes sending information back to your past self from elsewhere, impossible.
The direction would be from your past self to elsewhere, not the other way around.

I enjoy her humor, but SoL invariance ( and the reason why all observers measure the SoL to be the same, why you can't catch up to light, and why it takes increasing amounts of energy to approach the SoL barrier ) is the footing of the foundation of SR and GR.
Without it much of modern Physics crumbles to the ground, nd we know that both SR and GR have been immensly successful.
Maybe, as Sabine mentions, Quantum Gravity will redefine the singular points where v=c just as ( we hope ) it will for the singularity of Black Holes, leaving the rest of SR/GR unchanged.

[MJ kihara]

My thinking is it's possible and not just possible even further than it..i.e faster and further than speed of light...without violating SR and GR...the limit has been put by the already developed conventional models.

I don't think we were meant for a brief existence in this solar system.

[Janus]

On 4/9/2023 at 10:24 AM, MJ kihara said:

I don't think we were meant for a brief existence in this solar system.

I don't think the universe cares one way or the other.

[MJ kihara]

7 minutes ago, Janus said:

I don't think the universe cares one way or the other.

Why then bother bringing us into the existence... finding ourselves asking this question.

24 minutes ago, Janus said:

I don't think the universe cares one way or the other.

If it doesn't, it teaches us by observing it.if a supernova happens in our neighborhood star....we know what gamma ray's will do to us.it has kept record for us,what happened to the dinosaur.

We know that given enough resources human can reproduce a lot to go and occupy those places..given that we are on top of animal intelligence it's incumbent upon us to figure out...how to do it(FTL).

[Phi for All]

26 minutes ago, MJ kihara said:

Why then bother bringing us into the existence... finding ourselves asking this question.

The universe brought us into existence? Do you have a link that explains how this was established?

[Genady]

40 minutes ago, MJ kihara said:

Why then bother bringing us into the existence... finding ourselves asking this question.

Who brought us into existence?

 

//x-posted with the above

Edited April 12, 2023 by Genady

[MJ kihara]

1 hour ago, Phi for All said:

The universe brought us into existence? Do you have a link that explains how this was established?

 

1 hour ago, Genady said:

Who brought us into existence?

 

//x-posted with the above

We are talking about FTL it could be better if the owner of this thread directs the discussion....esp when dealing with controversial questions..and esp with someone with powers to shut you up and lock you down in a blackhole cause he can't comprehend your explanations and thinking.

[zapatos]

8 minutes ago, MJ kihara said:

and esp with someone with powers to shut you up and lock you down in a blackhole cause he can't comprehend your explanations and thinking.

I can't comprehend your thinking on this one. Are you talking about God, Mod, or your mother?

[MJ kihara]

8 minutes ago, zapatos said:

I can't comprehend your thinking on this one. Are you talking about God, Mod, or your mother?

Where are you from...from nowhere to everywhere..😂 just look at my other thread.

[Phi for All]

54 minutes ago, MJ kihara said:

We are talking about FTL it could be better if the owner of this thread directs the discussion....esp when dealing with controversial questions..and esp with someone with powers to shut you up and lock you down in a blackhole cause he can't comprehend your explanations and thinking.

You're the person who made a claim about the universe in a thread about whether FTL travel is possible. It's in Speculations, but it's still a science subject. If you aren't able or willing to support your statements, please don't make them in the first place.

[Moontanman]

There is another video by on a science channel that explains why FTL equals backward in time and or a paradox every time but in the diagrams I see a flaw. It appears that instantaneous communication doesn't cause time travel unless it's from a spacecraft going slower than light. The diagram is part of the video and since a video causes such consternation here I haven't posted it. I've watched is many times and my conclusion appears to be valid.  

[MJ kihara]

7 minutes ago, Phi for All said:

You're the person who made a claim about the universe in a thread about whether FTL travel is possible. It's in Speculations, but it's still a science subject. If you aren't able or willing to support your statements, please don't make them in the first place.

It's not about supporting statements..it's about you asking questions intending at directing discussions in a manner that if you don't comphrend you lock someone down.

[Phi for All]

Just now, MJ kihara said:

It's not about supporting statements..it's about you asking questions intending at directing discussions in a manner that if you don't comphrend you lock someone down.

No, it's about this site requiring mainstream explanations about science. If you had scientific support for your sentient universe concept, you could present it here to support your statements. You get locked down because you keep making the claims but can't come up with a decent explanation without using magic or woo. We comprehend just fine, thanks. If you don't understand something, you should ask other people who do. That's how science works. '

Making up things you can't support isn't science. Keep it out of here.

[swansont]

25 minutes ago, Moontanman said:

There is another video by on a science channel that explains why FTL equals backward in time and or a paradox every time but in the diagrams I see a flaw. It appears that instantaneous communication doesn't cause time travel unless it's from a spacecraft going slower than light. The diagram is part of the video and since a video causes such consternation here I haven't posted it. I've watched is many times and my conclusion appears to be valid.  

If the craft was going FTL I think the same problem is still there

[MJ kihara]

24 minutes ago, Phi for All said:

No, it's about this site requiring mainstream explanations about science. If you had scientific support for your sentient universe concept, you could present it here to support your statements. You get locked down because you keep making the claims but can't come up with a decent explanation without using magic or woo. We comprehend just fine, thanks. If you don't understand something, you should ask other people who do. That's how science works. '

Making up things you can't support isn't science. Keep it out of here.

Pliz sentient is not consciousness...it's just part of consciousness.

If u sent a rocket past a planet inhibited by natives whose scientific knowledge is limited and they realize the rocket is manouevrable in unpredictable manner...they will interprate it to be a conscious object....therefore consciousness is not all about feeling pain...it's about responding and making decisions.

In this case the rocket will be following instructions put in it in whatever form or following commands from back here on Earth.

19 minutes ago, swansont said:

If the craft was going FTL I think the same problem is still there

Traveling back in time is impossible for an evolving universe..it's not(universe) stuck in time.

If u move FTL 'if possible' u simply arrive a head of light....it's like two ancient warring communities one uses a donkey and the other uses a horse to sent message...the one using a horse which is faster will have an upper hand in manipulating situation..but as the message is being sent the situation in the battle field will still be evolving.

1 hour ago, Moontanman said:

There is another video by on a science channel that explains why FTL equals backward in time and or a paradox every time but in the diagrams I see a flaw.

The issue of backwards in time,I think comes from the idea of looking up in space and seeing the way the universe used to be earlier because light doesn't move instantaneously it take time to arrive...however where it came from is still elvoving...if we happen to move there(source of light) instantly,we will not have moved back in time,we will just get it as it is...it's present form as it's evolving...let say it was a star as we look at the telescope several billion years ago...then it happened to collapse to a blackhole that later evaporated through emission of Hawking radiation...all this as the universe is evolving then we move there instantly we will just get a spacetime fabric without a star.if the universe is elvoving uniformly (at the same rate across) then we come back home we will get things going on as usual with the time difference being equivalent with the time spend out there.

[swansont]

1 hour ago, MJ kihara said:

Traveling back in time is impossible for an evolving universe..it's not(universe) stuck in time.

If u move FTL 'if possible' u simply arrive a head of light....it's like two ancient warring communities one uses a donkey and the other uses a horse to sent message...the one using a horse which is faster will have an upper hand in manipulating situation..but as the message is being sent the situation in the battle field will still be evolving.

We’re discussing physics, not animal husbandry.

[MJ kihara]

16 minutes ago, swansont said:

We’re discussing physics, not animal husbandry.

Using the current models going FTL is impossible cause u keep pumping in alot of energy while warping spacetime until u get your self collapsed into a blackhole to realise you going nowhere.. wormhole and warp drive enormous energy til you wonder where to stand in the space as u make it.

We need a model where energy issues are minimised and or reinterprate lorentz factor so that we redifine energy...to take into consideration of square root of a negative.

[swansont]

1 hour ago, MJ kihara said:

Using the current models going FTL is impossible cause u keep pumping in alot of energy while warping spacetime until u get your self collapsed into a blackhole to realise you going nowhere.. wormhole and warp drive enormous energy til you wonder where to stand in the space as u make it.

That’s going from sub-light to FTL.

1 hour ago, MJ kihara said:

We need a model where energy issues are minimised and or reinterprate lorentz factor so that we redifine energy...to take into consideration of square root of a negative.

Yes.

[Moontanman]

18 hours ago, swansont said:

If the craft was going FTL I think the same problem is still there

No, it was an instantaneous signal from a STL craft that caused a causality problem.  

Edited April 13, 2023 by Moontanman