Register to reply 
Your opinion on exceeding the speed of light means the ability to return to the pastby Sean Pan
Tags: opinion 
Share this thread: 
#19
Apr2712, 05:01 PM

Mentor
P: 11,599

So the graph uses a lorentz transformation correct? The tachyons appear to travel back in time because the lorentz transformation is set up as c as the speed limit? IE if 10c was the speed limit then the tachyons would not travel back in time? I'm just asking about the math aspect, not the real physical aspect.



#20
Apr2712, 05:24 PM

P: 3,967




#22
Apr2712, 05:39 PM

P: 255

Of course that's the point, the gun was fired by the corpse unless we insist that the timelike loop must be selfconsistent. 


#23
Apr2712, 05:45 PM

P: 255




#24
Apr2712, 05:48 PM

Mentor
P: 11,599




#25
Apr2712, 07:38 PM

Emeritus
Sci Advisor
PF Gold
P: 9,270

There are some really counterintuitive things about FTL particles. In particular, if I measure a particle going to the right at 10c, then someone going to the right at 0.5c will measure the particle going faster than 10c, not slower. 


#26
Apr2712, 09:01 PM

P: 1,162

Teleportation came up in another similar thread. Instantaneous translation between points. Absolute simultaneity of events at separate locations. Assuming teleportation to a distant location in the same frame; How do you calculate the proper time at the point of arrival?? Given t=0 at point of departure. BTW Congrats. 


#27
Apr2712, 09:53 PM

P: 3,967

As mentioned in #18, the first time around the loop, Alex is alive between events E and H and the second time around he is dead between those same two events. This requirement for different histories probably requires the concept of parallel universes to make sense. Can we say FTL interaction not only implies travelling backward in time, but also implies parallel universes? 


#28
Apr2712, 10:25 PM

P: 3,967

An energy paradox involving time travel.
Let us say we have one very large uncharged lead battery and a small solar panel to charge the battery. We follow these steps: 1)We connect the solar panel to the uncharged battery. 2)We put a note on the uncharged battery saying "When this battery is charged please send it back to time 1" 3)Our future self obliges and sends the charged battery back in time. The first time a battery is sent back fully charged, we still have the initial uncharged battery. the second time a charged battery is sent back, we have the initial uncharged battery and two fully charged batteries. Repeat as often as required. We could in principle end up with more batteries than there is lead on the Earth to make them with and with a greater energy store than the total energy impinging on the Earth from the Sun between times 1 and 3. 


#29
Apr2812, 01:58 AM

P: 10




#30
Apr2812, 03:38 AM

P: 255




#31
Apr2812, 03:57 AM

P: 255

If you think of the quantum wavefunction going round the loop and Young's Slits as an analogy, we could surmise that nonconsistent outcomes lie in the dark bands of destructive interference when calculating their probabilities using the sum over histories method. 


#32
Apr2812, 04:12 AM

P: 255

It sounds as though you are disregarding what has been said so that you can believe in FTL without dealing with its consequences. 


#33
Apr2812, 04:56 AM

Emeritus
Sci Advisor
PF Gold
P: 9,270

I don't think I understand the question. Since you mentioned absolute simultaneity, you seem to be asking about instantaneous messages in Galilean spacetime. If there's absolute simultaneity, the question of "simultaneous in what coordinate system?" doesn't even arise. So if t=0 at the departure, then isn't t=0 at the arival too, by definition of "instantaneous". "Proper time" is a property of a curve in Minkowski spacetime, not a point. The concept of proper time isn't needed in Galilean spacetime. (We would have to define it as the coordinate time difference between the endpoints). The post I linked to in #6 deals with instantaneous messages in Minkowski spacetime. 


#34
Apr2812, 11:05 AM

Sci Advisor
PF Gold
P: 1,843




#35
Apr2812, 06:21 PM

P: 1,162

Does this clarify my question?? Thanks 


#36
Apr2812, 06:32 PM

P: 1,162

So the absolutely instantaneous definition is applied to the phenomenon of teleportation. So are you saying here that in a SR context the arrival time would be t=0 ?? Thanks 


Register to reply 
Related Discussions  
The speed of light, the term light year , and reference frames.  Astronomy & Astrophysics  8  
Did past technical experience + physics degree help you get the job?  Career Guidance  3  
Using light to see the world requires speed of light to be maximum?  Special & General Relativity  23  
To listen means you have to acknowlege or agree with what is being said, no?  General Discussion  18  
Kodama means echo or spirit of the trees  Beyond the Standard Model  1 