[Physics] Physics Digest, Vol 19, Issue 5

Fri Nov 23 17:18:23 CET 2018

Hi Tom (that's you right?),

    Yes, interesting, and perhaps your example is a little different, as it
is not a literal contradiction exactly. I always look at relativity theory
as being a sort of anagram of ether theory. If particles are composed of
waves in the manner conceived of by Schrodinger and deBroglie, and the
speed of light is the speed of these waves in some form of absolute space,
then matter can't exceed the speed of the waves that compose it without
falling apart. Einstein rearranged absolute space and time with the
time-space continuum, but in my opinion he arrives at the correct answer
without being able to provide proper physical explanations, since the speed
of light then becomes an absolute constant without any physical reason. So
yes, I also keep on asking "why?"

Doug

On Fri, Nov 23, 2018 at 5:02 AM carmam at tiscali.co.uk <carmam at tiscali.co.uk>
wrote:

> Doug, I have been troubled by relativistic concepts for many years, the
> one which is most easily proved wrong is that "no material body can exceed
> the speed of light".
>
> Here is that proof : -
> Imagine a space rocket, which is propelled by ejecting a small amount of
> matter (the rocket exhaust) at high speed from the rear, so imparting a
> thrust in the opposite direction. We will assume that the exhaust velocity
> is 3,000 m/s and the mass of the rocket is 30,000 Kg (very similar to
> NASA's Mercury-Redstone rockets). Now we can use the Lorentz transformation
> to find the new mass. The velocity between exhaust and rocket is 3000 m/s,
> so :-
>
> m = m0 / sqrt( 1 - ( v / c )^2)
> m = mass of rocket at velocity v as measured by the essential observer
> (Remember that Einstein's observer, properly called the essential
> observer, is always at rest relative to the motive force. In this example
> therefore, the essential observer is in the same frame as the rocket
> exhaust).
> m0 = 30,000 Kg (proper mass of rocket or rest mass when v = 0)
> v = 3,000 m/s - rocket's velocity relative to the exhaust
> c = 300,000,000 m/s
> Therefore m = 30000 / sqrt( 1 - (3000 / 3e8)^2) =
> 30000.0000015000000001125 Kg
>
> The mass increase is therefore 0.0000015 Kg or 0.0015 gram which is simply
> not measurable compared to 30,000 kilograms. For all intents and purposes
> the mass increase is zero. A further point to note here is that the mass
> increase is measured against the exhaust which is providing the motive
> force, and no matter what the velocity of the rocket when measured against
> its starting point (or anything else for that matter), the velocity between
> rocket and exhaust never changes, so the rocket mass is always
> 30,000.0000015 Kg (disregarding the loss of mass due to fuel used). In
> other words, the mass is fixed at 30,000.0000015 Kg for the values used
> above between rocket and xhaust, and the extra 0.0000015 Kg is an
> insignificant amount. As there is no significant mass increase with
> velocity, and certainly no accumulative mass increase, there is no
> theoretical upper limit to the velocity of the rocket.
> It therefore follows that as the mass increase is virtually zero, m
> aproximates very closely to m0. If the acceleration is regulated to 1g for
> the comfort of the crew, the space ship can reach an enormous velocity, and
> time on this space ship will pass at exactly the same rate as back at home
> on earth. "The effects of gravity are indistinguishable from the effects of
> acceleration" [Albert Einstein].
> I know that relativists would say that the mass increase has to be
> measured relative to the starting point of the rocket, but why is that?
> Einstein used the (essential) observer against which to measure the mass
> increase, with the tacit assumption that the starting point was where the
> propulsion unit was located, as in a particle accelerator. With that
> assumption, it is reasonable to refer the mass increase to the starting
> point. If we assume the propulsion unit (rocket motor) is remote from the
> rocket, then it is perfectly true that the rocket cannot exceed the speed
> of the rocket exhaust, as a particle in a particle accelerator cannot
> exceed c.
> This is analogous to a space vehicle which uses light sails for
> propulsion. The sails are deployed in the vicinity of a star (the sun), and
> the light hitting the sails imparts a tiny acceleration away from the sun.
> This acceleration will propel the vehicle away from the sun, and the
> velocity will gradually but steadily increase. As the vehicle approaches
> light speed however, the energy from the light striking the sails gets less
> and less, and the acceleration gets less and less. The light propelled
> vehicle cannot reach or exceed the speed of light.
>
> This was on my web page titled "Problems with Relativity", but my service
> provider (TalkTalk) no longer allows web page hosting, and I have yet to
> find another host.
>
> ----Original Message----
> From: dm88dm at gmail.com
> Date: 22/11/2018 18:00
> To: "General Physics and Natural Philosophy discussion list"<
> physics at tuks.nl>
> Subj: Re: [Physics] Physics Digest, Vol 19, Issue 5
>
> Hi All,
>
>   I recently have found a couple of relativistic concepts that I have
> found logically disturbing and thought I would throw them out there.
>
> The first is Einstein's redefinition of time as "that which a clock
> measures" which differs in a dramatic way from the more classical
> definition of time as being "the duration between events" or "the duration
> of an event". To give an example, if three observers watch a sunrise on
> earth, then two of them fly in opposite directions around the earth while
> the third stays put, and meet back at the same place where they then watch
> the sunset, all three will disagree on the elapsed time for sunrise to
> sunset using clocks they have carried with them. In other words, according
> to Einstein, there is no actual constant duration between the sunrise and
> sunset, even though all witnesses are present in the same velocity frame
> for the start and finish. Further, the idea that the number of ticks on the
> clock defines how far you have progressed into the future would also be
> wrong according to Einstein, since all the clocks would have different
> ticks even though the share the same present at the start and finish. Why
> are these contradictions not fatal to Einstein's theory?
>
> The second has to do with the statement
>
> “indeed that the speed of light is actually more fundamental than either
> time or space”
>
> -
> http://www.exactlywhatistime.com/physics-of-time/relativistic-time/
>
>
> However, the speed of light depends on both “time” and “space (distance)"
> = distance/time
>
> Is this not a circular argument – that a phenomenon that depends on time
> and space is more fundamental than time and space?
>
> It is a bit like saying the speed of sound in air is more fundamental than
> air and time.
>
> Anyone else bothered by this ??
>
> Doug
>
>
>
>
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