On 11-09-26 01:56 AM, Dr Josef Karthauser wrote:
On 23 Sep 2011, at 20:46, Stephen A. Lawrence wrote:
On 11-09-23 03:30 PM, Dr Josef Karthauser wrote:
From first principles if one starts with the notion that everyone
should see light as travelling at the same speed, then a simple
derivation naturally leads to the Lorenz contraction from which all
of special relativity is constructed. Then we go on to see that that
length contraction and time dilation must occur; a natural
consequence of the contraction equation. And, we have to ask the
question "how can a body have infinite mass"? Naturally we give up
and say that it can't and so it can't happen.
Not exactly.
The actual conclusion is not that no body can go as fast as C.
(Obviously, it can -- photons do.)
In fact, the conclusion is also not that no body can go /faster/ than
C. (In fact, it's SR which gave rise to the idea of tachyons.)
Rather, the conclusion is that */information/* cannot be transmitted
faster than C in any arbitrary reference frame, because to do so
leads to contradictions. Nature may or may not abhor a vacuum but
I'm pretty darn sure Nature abhors a contradiction.
See, for instance:
http://www.physicsinsights.org/ccentipede.html
Note, however, that FTL communication would entail no contradictions
if it were restricted to a /single, distinguished inertial frame./
The problems arise when we allow FTL communication in an arbitrary
frame. With such a free for all, signals relayed from one frame to
another can arrive before they leave.
Hey Stephen,
Ok, I agree. I was a bit careless with that paragraph; however, I'm
still not sure how a hard conclusion about the maximum velocity of
bodies can be derived from that approach. The link you used included
by example of the kinds of contradiction that can occur if you allow
superluminal communication starts with the phrase "Relativity
forbids/travel/at speeds faster than light," which goes against your
previous paragraphs. They obviously think that SR shows that, as do
most people.
Ummmm.... In fact, "they" is "me", because I wrote that page. I'm the
one who used that phrase, and I just gave you my view on it, which is
that the valid conclusion which can be drawn is a lot less strong than
the statement "no body can go faster than light".
Gotta watch these sloppy phrases.... The point of the page was to show
the problem with information transfer, rather than say anything much
about rapid transit.
Also, in my story that I tried to tell later in my email, I did not
require information exchange between the relative frames. Rather,
explicitly I spoke about two frames becoming "Lorentz disconnected",
and I tried to suggest that the transition that would occur as the
change in relative velocity between the two frames passed through the
singularity in the Lorentz transformation was not excluded by nature
and that our thinking around the discontinuity was a limitation of our
imaginations not the Universe.
I'd be interested in your thoughts about that, if you've got a moment
to consider them.
I don't understand what it means to be "Lorentz disconnected".
If they can communicate with each other then it seems like they're
causally connected -- or, rather, certain events in one frame may be
causally connected to events in the other frame, by dint of being in the
backward light cones of those events.
What did I miss? Is there a link I didn't follow somewhere? (wouldn't
surprise me -- I'm not spending a lot of time on this and I haven't read
all the foregoing messages.)
Yours,
Joe
