On Tuesday, August 17, 2021 at 10:25:52 AM UTC-7,
det...@newsguy.com wrote:
> You can create a mathematical model where the spaceship is stationary,
> and the earth is moving, but it would have NOTHING to do with reality.
That's untrue, because both of the reference systems provide equally valid descriptions of the actual physical phenomena. To dispute this, you would need to explain why the description in terms of one reference system has to do with reality while the equally valid description in terms of the other reference system does not.
> The pulses from the pulsar result from the pulsar rotating once every ten seconds.
Well, your scenario stipulates that the pulses hit the earth once per 10 seconds in the direction perpendicular to the line from Earth to Alpha Centauri, and this is really all we need to know. If you want to relate this to the description in terms of the pulsar's reference system, you can do that, but it doesn't change the relevant aspects of the scenario. There are infinitely many different combinations of conditions of the pulsar (rotation rate and relative speed and direction of motion) that would yield the stipulated conditions, all irrelevant to the discussion.
> Those pulses hit the earth once every ten seconds.
Right, this is what you are stipulating, so there's no need to discuss the description in terms of the pulsar's reference system.
> When the spaceship travels at a right angle to those pulses, any "Doppler Effect"
> is IRRELEVANT.
Well, in the transverse condition this is merely a matter of semantics, since the relativistic Doppler formula includes the effect of time dilation, which is why there is a Doppler shift even for purely transverse motion. If you prefer to call that "time dilation" rather than "Doppler", that's fine, but just be aware that the common terminology refers to it as transverse Doppler. And, no, it is not irrelevant at all. The Doppler effect is significant in the descriptions for both reference systems.
> The Doppler Effect is about the frequency of light WAVES ...
The generic Doppler effect doesn't just apply to things like electromagnetic waves, it applies to every kind of propagating frequency. For example, if the machine gun on an jet fighter shoots 3 bullets per second, and the plane is approaching you at 500 mph, the bullets will hit you at a higher frequency as given by the Doppler formula. It applies to the frequency of any propagating sequential entities, not just wave crests or oscillations of electromagnetic fields.
> While there might be some Doppler Effect when the spaceship hits the
> photons in the rotating light beam, that effect will NOT IN ANY WAY change
> how FREQUENTLY the ship OR EARTH will hit those rotating BEAMS.
You're mixing up two different frequencies: (1) the frequency with which the beams hit something, and (2) the frequency of the electromagnetic oscillations comprising the beams. Those are totally different frequencies, and the relevant frequency for your scenario is the frequency with which the beams hit the objects. The Doppler effect and the motions of the objects determine those frequencies. You need to stipulate the conditions of your scenario if you want to relate the frequencies in the pulsar's reference system to the frequencies in the earth's or the ship's reference system, or you can just stipulate that the pulses strike the earth once per 10 seconds, and then you don't need to worry about the pulsar's reference system.
In any case, once you've stipulated that the pulses strike the earth once per 10 seconds, that is the frequency with which the pulses strike the earth, and it applies regardless of which reference system we use to describe the events. Likewise we have established that the pulses hit the ship at a frequency of once per 1 second, and this too applies regardless of which reference system we use. So, you can calm down and stop shouting that we can't change the frequency the beams hitting the earth or the ship. Those frequencies have their stipulated values in terms of both reference systems. So neither reference system is better or more accurate than the other.
> The earth is NOT moving away from the pulsar.
Again, you can stipulate how the earth and the ship are moving (or not moving) relative to the pulsar, however you like, but the bottom line is that you are saying the pulses strike the earth once per 10 seconds, and the rays are perpendicular to the line from Earth to AC in terms of the earth's reference system. That is all we need to know.
> The pulses will still hit the ship once per ship second when the ship is traveling
> at 99.9488339567% of the speed of light.
I think you have a typo in that number (transposed 9 and 4), but yes, as explained repeatedly, the pulses hit the ship once per ship second, and this is true regardless of whether we describe the events in terms of the earth's reference system or the ship's reference system (or any other reference system). Nevertheless, as explained previously, we have reciprocal time dilation.
> Your screwball BELIEFS do not change anything
I wish I could take credit for them, but they are not uniquely "my" beliefs, they are elementary Relativity 101. Anyone who has even a rudimentary understanding of relativity will instantly give you the same explanation.
> and ALL TIME DILATION EXPERIMENTS show you are WRONG.
No, as you may recall, we invalidated all your purported counter-examples, because they all refer to either difference in gravitational potential or accelerated clocks. Reciprocal time dilation applies to the reciprocal slowness of each clock in terms of the *inertial* coordinates in which the other clock is at rest. This has been abundantly verified experimentally, and there are no counter-examples.
In summary, your pulsar scenario is a good illustration of reciprocal time dilation.