Recent content by Grasshopper

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    I Falling into a black hole: blueshift questions

    Okay so back to tidal forces and size: Am I mistaken that being close to a super massive black hole you’d feel gentler tidal forces than close to a stellar mass sized black hole? What about if you were at the event horizon for each?
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    I Falling into a black hole: blueshift questions

    Ah yes, of course, you measure it, thus it is not coordinate dependent. So, as you cross the event horizon, blueshift at best would be moderate. Does this also depend on the size of the black hole? I am under the impression that tidal forces depend on the size (if altitude is the same, larger...
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    I Falling into a black hole: blueshift questions

    I am under the impression that an outside observer would see things redshifted as the person they are observing approaches the event horizon. So, it seems reasonable that someone from inside the black hole would see incoming light blueshifted. Is this inaccurate? Why or why not? If it is...
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    COVID Reaction to COVID-19 Vaccine (or what to be prepared for)

    Perhaps, but look at the world we live in today. What was fringe fifteen years ago is now proudly shared online, and millions get their minds infected with things like flat earth stupidity, QAnon stupidity, and on and on. We used to laugh at conspiracy theorists. Now they are making public...
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    COVID Reaction to COVID-19 Vaccine (or what to be prepared for)

    There is one and only one type of source anyone should be trusting or posting here, IMHO: peer reviewed scientific publications.
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    I Black hole inside of a black hole... can it be done?

    This is excellent stuff. But since @mitochan brought up colliding BHs, I have a related follow up question: Nothing can travel faster than c, so would this not prevent two colliding BHs from ever instantly becoming one? Because presumably the two singularities are separated by a non-zero...
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    I Black hole inside of a black hole... can it be done?

    Let's say you have an absolutely giant black hole, so big that items inside of it leisurely approach the singularity, reaching it in about a million years (or whatever time it takes for a black hole to form from matter accumulation). Could matter slowly accumulating somehow form its own black...
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    COVID Reaction to COVID-19 Vaccine (or what to be prepared for)

    Kind of makes you wonder why this isn’t being done already given it’s supposed to be intramuscular. Is it particularly time consuming? I wouldn’t know. EDIT — upon reading more, it seems the concern isn’t enough to make it a widely practiced part of IM injection.
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    B Why does it require an infinite amount of energy to reach the speed of light?

    I myself have wondered if that's even physically possible, with all the quantum weirdness. I'm of course fully ignorant about QM, but the thought has crossed my mind. Not that it matters, since in physics simplifying models are used to isolate particular paths of inquiry.
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    I Conservation of momentum in a collision

    Excellent explanation. Thank you for coming back this. It is interesting, as PeterDonis pointed out in post #42, that you only have two choices. But seeing it this way helps me get a better a snapshot of all the balls that were being juggled by these people early in the 20th century trying to...
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    B Why does it require an infinite amount of energy to reach the speed of light?

    That’s a great Insight, but one thing I’ve wondered is why the concept of relativistic mass was even invented, other than the need to keep equations more familiar. Is there another more useful reason for it being created?
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    I Express the acceleration in terms of force and velocity in SR

    Not with knowledge of the term but I suppose yes. But yeah, as a student I will agree that standard Minkowski diagrams are more intuitive. Loedel diagrams may have some usefulness, but not at the expense of opening the door to more confusion. There’s enough unintuitive stuff to worry about...
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    I Express the acceleration in terms of force and velocity in SR

    Yes. But presumably you could use the simple Pythagorean trig identity by replacing ##γ^{-1}## with ##\frac{1}{γ}## could you not? (I wonder if that would be of use at all) That is, ##γ^{-2} = γ^{(^-1)(2)} = (\frac{1}{γ})^2## ##\beta^2+(\frac{1}{γ})^2 = 1## looks the same to me. But even if...
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    COVID Reaction to COVID-19 Vaccine (or what to be prepared for)

    I was told by the nurse if you’re going to have a dangerous reaction, it’s most likely after. Maybe stay vigilant.
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    I Express the acceleration in terms of force and velocity in SR

    But that surely means you can easily change those to trig functions. I am now intrigued. That negative power raises a small problem, but surely there is a simple work around I’m missing. An i or something.
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