PeterDonis's latest activity
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PeterDonis replied to the thread High School Car spinning on a frictionless sheet of ice = absolute motion?.It isn't. None of the forces that are actually felt are "centrifugal forces". See post #6. -
PeterDonis replied to the thread Undergrad Does the scale factor need to be normalized?.Yes, but it's easy to generalize it to not require that: just define the ratio of scale factors at the two times to be equal to ##1 /...
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PeterDonis replied to the thread Undergrad Does the scale factor need to be normalized?.What is "exactly the same"? Be specific.
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PeterDonis replied to the thread Undergrad Does the scale factor need to be normalized?.That isn't the new "unit" of ##c##, that's the new value of ##c## in your new chosen distance units (and the same time units as before)...
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PeterDonis replied to the thread Undergrad Does the scale factor need to be normalized?.What is also true? Think carefully. The distance unit in terms of the scale factor is. In other words, the distance that a scale factor...
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PeterDonis replied to the thread Undergrad Does the scale factor need to be normalized?.That's only true if you define the scale factor "now" as ##1##, and you're using light-years as your distance unit. But both of those...
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PeterDonis replied to the thread Undergrad Does the scale factor need to be normalized?.Yes. I'm not sure what you think the word "normalized" means.
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PeterDonis replied to the thread Undergrad Does the scale factor need to be normalized?.Ok. No, it's equal to ##1 / (1100 + 1)## Ly, since that's the distance that a scale factor of ##1## corresponds to with your...
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PeterDonis replied to the thread Undergrad Does the scale factor need to be normalized?.The form of the integral would be the same. But the numerical value of the function ##a(t)## that appears in the integrand would be very...
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PeterDonis replied to the thread Undergrad Does the scale factor need to be normalized?.It will certainly change the numerical value of the result because redefining the scale factor means redefining the units of distance...
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PeterDonis replied to the thread Distinguishing Mathematical Consistency from Physical Realizability.Thread closed for moderation.
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PeterDonis replied to the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars).To add a clarification: when you do, please limit discussion to how the standard model of our solar system used by astronomers accounts...
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PeterDonis reacted to DaveC426913's post in the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars) with
Like.
Sorry, I have to recap. Your post 63 shows three conjunctions - one of which is during retrograde. OK, so now I have to go all the way... -
PeterDonis reacted to PeroK's post in the thread Undergrad Are Boltzmann brains predicted by our current cosmological theories? with Like.
An entangled system of two particles, as it is usually presented, is a state associated with non-relativistic QM. How it is understood...
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PeterDonis reacted to Sylvain9595's post in the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars) with Like.
Everything is clear for me now, thanks.