Re: What is the most plausible FTL/Hyper/Warp Drive that you come accross?

raphfrk@xxxxxxxxxxxx wrote: 
Erik Max Francis wrote:

raphfrk@xxxxxxxxxxxx wrote: 

I think a system where a special reference is defined over all space
time that is dependant on matter/energy distribution of the universe
would not count as breaking relativity.  Perhaps, the reference defined
by cosmic background radiation could be used.  The cosmic background
configuration is arguably a matter of history rather than physics.


Except it doesn't work.  At rest with respect to the cosmic background
here is not at rest with respect to the cosmic background elsewhere.  It
doesn't constitute a universal reference frame.

Erik, could you expand on that, IOW you're saying that the CMBR isn't at rest WRT itself?

IIUC the idea of using the CMBR as a universal reference frame is that since the CMBR gets steadily colder as time progresses from the BB, once we get ourselves into a state of motion where the observed CMBR in all directions is at (or averages to) the same temperature T; we then know "when" we are in history.

So two observers could synch their clocks by coming to rest WRT each other and the CMBR, boost as they liked for arbitrary times, then individually boost so that they each measured the CMBR T as constant over their fields of vision, then know their "relative absolute times" WRT each other so as to remove ambiguities in their common observations of a third phenomenon.

My understanding was that that was not a problem.  As long as you have
a reference frame defined everywhere, causality is preserved.  All the
references don't have to be stationary wrt each other.

You mean, as long as they are sub-c WRT each other? Isn't this what you're trying to avoid, that the parts of a universal reference frame are in motion WRT each other?

The real objective is to define a surface of points that are
simultaneous.  This probably prevents an arbitrary function for the
reference frame function.  However, the function doesn't have to be
constant.

Two irreconcilable requirements. Two observers (two points on your surface) in motion WRT each other _cannot_ have simultaneity. Moving clocks slow WRT each other, and all that.

ISTM this idea, of simultaneity definable over distances greater than a few meters, is a Newtonian leftover that impedes comprehension of Relativity.

The are other options other than the cosmic background.  Something like
the average momentum of all the particles in the universe.

This also is not well-defined in general relativity.

Well, it can't be, since information about the rest of the Universe has to propagate to each particle at c or less. By the timethe information gets there of course, things have changed.

Yeah, I know, I said the following after the quote above:

raph...@xxxxxxxxxxxx wrote:

Ofc, there is a problem that such a
definition requires the frame to exist in order to perfrom the
averaging.


To have absolute momentum, you need an absolute frame so that
particular definition is circular.  I guess I was thinking of some way
that nearby massive objects could be used to define the frame.

But it only defines it locally, _if_ the objects are inertial WRT each other, yes?

Another option wrt FTL is the empire time method.  Wormholes can be
created with mouths right beside each other.  One mouth is then
accelerated at high speed to another system.  The CPC destroys any
wormholes (or wormhole circuits) that would cause causality problems.
The mass of all holes in the circuit increase until the one with the
least amount of negative mass collapses due to not having enough
negative mass to maintain stability.   Maybe there would even be
Kirchoff's Laws for worm holes :).


  Now _there's_ an idea.


  Mark L. Fergerson

.

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