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comment by am_Unition
am_Unition  ·  1763 days ago  ·  link  ·    ·  parent  ·  post: Why the world is waiting for Betelgeuse to go supernova

Did you do it like:

d(t' = t/š›¾), with š›¾(t), after substituting v=9.8*t into š›¾(v), and then integrate both sides, solving for the upper limit of the t' integral?

Unprimed is Earth's frame, for posterity.

Also, "approaching shitfaced at 1 g": not sure if claiming to be drunk or ugly... :|

Edit: no but if you really hate yourself, do d(š›¾*t' = t), with š›¾(t), and then do algebra for days. It reminds me of some homework shit once with deriving a particularly simplistic expression algebraically for a Rankine-Hugoniot shock jump condition expression.





Devac  ·  1762 days ago  ·  link  ·  

Drunk. Probably still are. Definitely had too much, but flatmate finally got his M.Eng after years of bullshit, so at least it seemed like a good occasion.

    but if you really hate yourself, do d(š›¾*t' = t), with š›¾(t), and then do algebra for days.

I have a math major and loved courses like real analysis, so obviously started drinking and deriving from Lorentz transform. For kb's case I got:

  t = sqrt(xĀ²/cĀ² + 2x/g)

t' = (c/g) asinh(gt/c)

x - distance from stationary frame's perspective.

Mea maxima culpa if I fucked it up along the way, but it looks reasonable to me.

am_Unition  ·  1762 days ago  ·  link  ·  

Looks good to me. I might come back with pictures of my chickenscratch, but yeah, I can see how some geometric substitution in the integral leads to a sinh function.

Perhaps somewhat ironic is that the asinh function is sometimes pronounced "a cinch", a.k.a. American slang for something considered easy. But some would say "arc shine". As for "inverse hyperbolic tangent", it's just that no one wants to take the time to say an 8 syllable thing. The fact that pronunciation runs the gamut is proof that we've needed to standardize communication since science got off the ground. It's just dumb luck that I'm born into the English-speaking contingent of the world. But meanwhile, you know at least two languages thoroughly, and your brain is all the more ductile for it. Long term benefit! But yeah, I do genuinely feel kinda guilty for just having been born in the U.S., for what seems like an ever-increasing number of reasons, when I consider it.

For now, at the very least, enjoy that booze. Kill off the weak brain cells. You'll make more, no worries.

Devac  ·  1762 days ago  ·  link  ·  

  t' = Integral[1/sqrt(1 + (gt/c)Ā²), {t,0,t}] = (c/g) ln(g/c + sqrt(1 + (gt/c)Ā²)) = (c/g) asinh(gt/c)
am_Unition  ·  1762 days ago  ·  link  ·  

That's it, thanks :). I promise to never outsource looking up integral tables for another few posts.

user-inactivated  ·  1763 days ago  ·  link  ·  
This comment has been deleted.
am_Unition  ·  1762 days ago  ·  link  ·  

FutureNeg: bebe, U pretty on the surface (Earth's), but at the 2 g's we gotta get to Titan at, that's just U 2 shitfaced 4 me, srry~