Sagittarius A-Star's latest activity
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Sagittarius A-Star replied to the thread Undergrad Do photons have mass? Why not?.The mass of a moving rock is ##{E \over c^2}\sqrt{1-v^2/c^2}=m##. The photon is massless because it is moving with ##c##: ##{E \over... -
Sagittarius A-Star reacted to Ibix's post in the thread Undergrad Transit time for a round trip to Alpha Centuri... with
Like.
Alternative to @Sagittarius A-Star's rapidity method, you can use ##v/c=\frac{at/c}{\sqrt{1+a^2t^2/c^2}}##. Using years and light years... -
Sagittarius A-Star replied to the thread Undergrad Transit time for a round trip to Alpha Centuri....I assume you mean the scenario, which you described in the OP. The peak speed is reached in the middle between Earth and Alpha...
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It's not so clear if that is actually a failure or just part of the deployment plan. Early Starlink satellites sometimes needed three...
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Sagittarius A-Star replied to the thread Space Stuff and Launch Info.All 16 of Russia's latest satellites for its Starlink rival failed to reach their intended orbit...
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Sagittarius A-Star replied to the thread High School Randomness in quantum mechanics.For example, the electron hits a detector at some location. This paper describes a double-slit experiment with electrons (instead of...
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Sagittarius A-Star replied to the thread High School Randomness in quantum mechanics.The math model predicts a probability for a measurement result.
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Sagittarius A-Star reacted to Ibix's post in the thread High School Randomness in quantum mechanics with Like.
That there appears to be some inevitable stochasticity in the world. QFT respects the causal structure of relativity, so has clear...
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First German rocket to reach orbit. Germany was the first to reach space (a V2 in 1944) and is now the latest to reach orbit, 82 years...
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Sagittarius A-Star replied to the thread Space Stuff and Launch Info.Isar Aerospace has returned to the launch pad for Flight 2. The company is targeting NET 5 September to launch its qualification flight...
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Sagittarius A-Star reacted to PeterDonis's post in the thread High School Einstein equations don't work at large scale? with Like.
He derived the result that if a body emits radiation of energy ##L##, its invariant mass (in modern terminology) is reduced by ##L /...
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Sagittarius A-Star replied to the thread High School Einstein equations don't work at large scale?.Yes. Einstein derived it in his 1905 paper "DOES THE INERTIA OF A BODY DEPEND UPON ITS ENERGY-CONTENT?"...
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Sagittarius A-Star reacted to PeterDonis's post in the thread High School Einstein equations don't work at large scale? with Like.
##\gamma## plays many other roles besides the time dilation factor. That "derivation" assumed that ##E_0 = m c^2##, since you wrote...
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Sagittarius A-Star replied to the thread High School Einstein equations don't work at large scale?.This earlier post uses the time-dilation-factor in ##\alpha=\gamma^3 \frac{dv}{dt}## for deriving ##E = K + m c^2 = \gamma m c^2##...
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Sagittarius A-Star replied to the thread High School Einstein equations don't work at large scale?.QFT requires relative time. For example, QFT describes an electron/positron pair creation, which requires Einstein's ##E_0=mc^2##. The...