«Given the Moon’s weaker gravity (and movement differences between it and Earth), time moves slightly faster there. So an Earth-based clock on the lunar surface would appear to gain an average of 58.7 microseconds per Earth day. As the US and other countries plan Moon missions to research, explore and (eventually) build bases for permanent residence, using a single standard will help them synchronize technology and missions requiring precise timing.»
Coming up with some (presumably) correct + still reasonably short description seems more challenging (to me). My best attempt so far:
<blockquote>
<b>If</b> two astronauts had met "somewhere in (cislunar) space", and subsequently separated from each other,
with one astronaut venturing on to land on the lunar surface, and
the other astronaut returning to the Earth's surface,
such that (as may happen in selected trials)
it takes both astronauts exactly equally long, resp., from separating until reaching (halting on) the Moon, or on Earth,
after some (not further specified) while, either astronaut perhaps being prompted by suitable prearranged signals,
both again take off from Earth, and from the Moon, resp., and they meet again "somewhere in (cislunar) space", where again (trials must be selected such that)
the duration of one astronaut from her take-off until the re-union meeting
happens to be exactly equal to the duration of the other astronaut from his take-off until being together again
<b>then/therefore</b>
the astronaut who had stayed on the lunar surface had remained there
(pretty much) <b>exactly</b>
[\left(1 + \frac{58.7 * 10^{-6}}{86400}\right) \approx (1 + 6.8 * 10^{-6})]
<b>times as long as</b>
the astronaut who had stayed on the the surface of the Earth had remained there.
When you expect that you're kid has a fully blown eardrum, finding out it's "only" a small perf in one and infected blockage in the other seems not too bad.
It’s now thought that they could illuminate fundamental questions in #physics, settle questions about #Einstein’s theories, & even help explain the #universe.
…In recent yrs, the amt of data that scientists have discovered about black holes has grown exponentially.
It’s in these simple, outlandish objects, Broderick explained,“that 20th-cen #physics breaks down.”…Basically, there’s #Einstein’s theory of general #relativity (which made a tiny but far-reaching correction to #Newton’s concept of #gravity), & there’s #QuantumMechanics. “General relativity is thought of as the theory of the very large & massive, & quantum mechanics is the theory of the very small or very cold,” Broderick said. #BlackHoles are massive(gen relativity), & cold (quantum mechanics).
Dr. Elisa Maggio is a postdoctoral researcher in the “Astrophysical and Cosmological Relativity” department. She works on tests of gravity in the strong field regime with gravitational-wave observations and on tests of the nature of black holes.
Hendrik Antoon Lorentz Dutch physicist and joint winner (with Pieter Zeeman) of the Nobel Prize for Physics in 1902 for his theory of electromagnetic radiation died #OTD in 1928. He combined Newton's mechanical laws & Maxwell's electromagnetic laws to describe the motion of electrons. The results were peculiar, pointing to the need for a radical new theory. Without Lorentz, Einstein said, he would never have been able to discover special relativity. via @wikipedia
"I cannot refrain... from expressing my surprise that, according to the report in The Times there should be so much complaint about the difficulty of understanding the new theory. It is evident that Einstein's little book "About the Special and the General Theory of Relativity in Plain Terms," did not find its way into England during wartime....
I’m listening to a pop physics book and they’re on the subject of relativistic effects. They are making the (common) statement that mass increases as velocity increases.
“...a body moving at 87% of the speed of light relative to some observer, will be measured by that observer to have double the mass it has when it's not moving.”
I have a problem with this. How does an observer measure the mass of a moving object? They are not in the same reference frame. If the observer is not measuring mass, but a consequence of mass, e.g. momentum, shouldn’t the author be saying this, instead?
• #DarkMatter was first theorized in the 📆 1930s to explain movements of #stars 🎇 and #galaxies 🌌 that couldn't be explained by Newton's laws of gravity.
Albert Einstein and Marie Curie conversing in Geneva, July 1924.
Marie met Einstein personally in 1911, during the first Solvay Conference in Brussels. Einstein confirmed this fact in one of his letters:
"I am impelled to tell you how much I have come to admire your intellect, your drive, and your honesty, and that I consider myself lucky to have made your personal acquaintance in Brussels(…)"
Credits: AIP Emilio Segrè Visual Archives. Held by Niels Bohr Library & Archives
So FTL does not lead to time travel? This looks like something that is beyond the limits of my physics/maths to properly understand to know how valid it is. #physics#ftl#relativity#scifi
#PhysicsFactlet:
Signals (e.g. light) move at a finite speed, so there is a time lag between when they are emitted and when they are detected. If the source is moving, the detector will "see" the signal that was emitted at a previous time, not the signal that is being emitted right now, and this time lag can change with time in a complicated way.
(Notice that, as the source is always moving slower than the signal, the detector sees the signals in the same order they were emitted.) #Physics#ITeachPhysics#Electrodynamics#Optics#Relativity
Follow-up: if the source can move faster than the signal can propagate (which can easily happen with sound), the the emitter and the detector will not agree on the order of the signals, and thus on what happened first and what happened later. #Physics#Relativity#ITeachPhysics
So, I’m reading some light physics again (Brian Cox & Jeff Forshaw on the origin of Einstein’s E = mc^2), and once again have bumped into the ubiquitous statement in such books that time, unlike space, has an arrow and appears to be unidirectional (which strikes me as little more than a restating of the principle of causality).
I’m interested in any physicist’s perspective on the following thought I have whenever I read this proposition…
⚛ We've had relativity, the physics of time, genius, the speed of light, the Grand Unified Theory, photons, black holes, quantum physics - but this is the first time Melvyn Bragg and his experts have considered Albert Einstein himself.