Starlight

This is kind of fun for me because it as one of the first bits of physics I distinctly figured out for myself. The doppler shift of sound is detectable to the ear because the emitter of the sound; i.e., a horn, emits only a narrow band of the frequencies that we can perceive, while the red and blue shifting of light is not detectable because the emitter of light; i.e. a star, emits a much wider band than the eye can perceive. As a bit of blue light moves toward the violet, and beyond our perception, a bit of green moves toward the blue. This same fill in effect applies all the way down the line where red moving to orange is replaced by infrared moving to red, and into our perception. A horn emitting a range of frequencies between 500-750 Hz can shift a long way in either direction before it moves beyond the ears normal range of 20-20,000 Hz. Dang! You're just asking for it, aren't you. (Psst! It's not wrong, and you said almost the same thing anyway.) With the Hubble constant being 71(km/s)/Mps and M31 being 0.784 Mps distant the expansion is 55.7 km/sec. That in itself would be easily detectable; however, M31 is moving toward us at ≈100 km/s due to gravitational acceleration.What I'd be interested in learning is if the Hubble expansion is taken into account when calculating the timing of our collision with M31.

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It is far easier for you, as civilized men, to behave like barbarians than it was for them, as barbarians, to behave like civilized men.

No! Dragsters are really, really loud. You'd not be able to hear anythng. True. The blue shift will always give the current approach velocity; but, what will be the approach velocity one billion years hence. As M31 gets closer its velocity due to G acceleration will increase, which is easy to account for, while the Hubble expansion will decrease proportionally to the separation, complicating the situation. Does it shift the collision timing away from the easy calculation more then a percentage point or two? If the dog whistle's stationary frequency is <29 detectable.

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It is far easier for you, as civilized men, to behave like barbarians than it was for them, as barbarians, to behave like civilized men.

The instantaneous velocity of a photon is either c or zero. When the percentage of time of travel for the photon being zero is 99.99999433% during an interval the mean velocity is 17 m/s.it's not at all the same. Do you think you'd get off on a speeding ticket for doing 120 mph by telling the judge that you'd only been driving for 32 minutes and sat waiting for the ticket for 28 minutes for an average speed of 65 mph?Edited by lyx2no, : Opps! Hit the wrong button again. No edit.

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Ridicule is the only weapon which can be used against unintelligible propositions. Ideas must be distinct before reason can act upon them.

A few questions. In my post #57 I say that a photon has a velocity of either c or zero.

• Is this technically true? I mean, when a photon is absorbed, does it still exist, or is it a whole new photon that is emitted?
• What distinguishing features do photons have: energy, polarization (2 types) anything else?
• When an electron absorbs a photon of energy x and t psec later emits a photo at energy (x-y) and a second photon at energy y, are these 2 separate photons or the first photon now in two parts?
• Or are there, like, zillions of virtual protons hanging around inside of an electron waiting for assignment? This last being an entirely made up question from the fuzzy stuff in one of my brains darker corners.

Thank you.Edited by lyx2no, : Last question.

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Ridicule is the only weapon which can be used against unintelligible propositions. Ideas must be distinct before reason can act upon them.

Hi RCH I'd be very interested in hearing what these mistakes are. As I am now, save your congratulations all, a graduate of the 9^th grade I am less easily led astray then I was a few, short weeks ago. But I do have a certain degree of awe regarding cavediver which would likely blind me to his foibles. Consider me, if you will, one of the little children not to be led astray. I place myself in your hands to be delivered from his (cavediver's, in this instance) hands.If I could suggest a good place to start: In Message 59, before the current unpleasantness, I asked a series questions. Could you do me the service of answering them. They are real question that I really don't know the answers to, and have not been able on my own to find the answers to.The danger is that I might unwittingly, having formed an incorrect understanding of these points, use them in constructing more advanced arguments; i.e., my Message 57 to you. You could also, please, answer the question I posed to you there as well; not the rhetorical question per se, but correcting any error I would be making in assuming the cases are not the same.

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Ridicule is the only weapon which can be used against unintelligible propositions. Ideas must be distinct before reason can act upon them.

Not mine. Message 80

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Ridicule is the only weapon which can be used against unintelligible propositions. Ideas must be distinct before reason can act upon them.