« on: 07/07/2021 16:12:34 »
One more modern use for the centrifuge: The separation of isotopes. Used as a method to enrich Uranium for use as nuclear fuel.
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Hi all,Then there would be aberration and the effect gravity had on the light before it entered the pin hole. But all that would do is alter the initial angle that the light exits the hole relative to the chamber. It would be the same as a fixed light source that wasn't aimed at a point directly across from it.
So if we use Harri's example of a light beam passing through the experiment and also factor in Colin's pointQuoteThink. What have you fastened the light beam equipment to?
lets say you use sunlight as your light source, passing through a pinhole into the room/lab, streaming across the mid point would that not discriminate the points under discussion ?
Okay, we will assume that the source of the light is fixed relative to the ground. The light is turned on. The light, after leaving the source, will curve downward due to gravity. However since light travels so fast, it would take extremely accurate measurements to even notice that it hits the far wall a bit lower.
Could I ask, what if we return to the vacuum chamber where a bowling ball and feather are suspended from the ceiling. We then create a vacuum by withdrawing the air in the chamber. This time, midway between the objects and the floor we pass a light beam across their path. On release of the ball and feather what would reach the beam first, the ground or the objects? Or both simultaneously?
You are all so smart here, you know the equations. Maybe someone will be interested in recalculating the result of the Michelson-Morley experiment with a much smaller Earth orbit, and the speed of the Earth (approximately as in the schematic image below). Perhaps that experiment proved the existence of the aether, but was incorrectly interpreted as wrong due to the false parameters of the earth's orbit and the speed of the Earth in space.We can independently measure the speed of the Earth by noting the change of stellar aberration as it orbits. This value is in agreement with the value you get from dividing the size of the orbit by the time it takes to complete one orbit.
No, it just means that, in physics, the term "spin" when working at the electron level means something different than it does at the macroscopic level. It's simply a matter of context in determining which meaning is being used.The problem was already solved.
QM "spin" is not spin.
That requires you to ignore physical intuition.
It's like saying for something that does not obey Newton's laws: ""force" is not force".
And your estimation of the risk of meteor collision is extremely overblown.It also contradicts direct measurements (like the sizes of planets) and apparently relies on conspiracy theories (since you claim that interplanetary spacecraft aren't feasible because you say they'd be destroyed by asteroid impacts...).I claimed that space flights are unreasonably risky due to the inevitabile possibility of destruction in a collision with a meteorite, that is, in fact, they are meaningless.
To be fair, in order to escape a body, you eventually have to reach "escape velocity", it's just that it doesn't need to be the surface escape velocity. For instance, if your rocket has reached a distance of 6378 km above the Earth's surface, and is moving at 7.91 km/sec, It has achieved escape velocity for that distance from the Earth. It can cut its engines and coast, never to return.In order to escape from the gravitational field of a large object it's necessary to achieve escape velocity.Not so. Rockets have escaped from Earth without ever having reached the 11.2 m/sec escape velocity at its surface. A slow winch will do if you have one (like a space elevator).
You seem to be applying rules of inertial coordinate systems to non-inertial cases. Yes, given one rock falling in near the event horizon passing an identical rock going the other way at escape velocity, each of them will have near infinite mass relative to the local inertial frame of the other.
Relative to the distant observer, either rock has kinetic energy that cancels out the negative gravitational potential energy, leaving no change to the total energy of the rock. The rock has negligible coodinate speed (it never reaches the EH according to the distant observer), so the mass isnít a function of relativistic speed as you are painting it. Plus, the rock having more mass than does the black hole doesnít make sense.
The photon loses energy overcoming gravity. There is a certain amount of gravity at every point in space. Hence the photon loses energy with distance. Since the energy of a photon is not unlimited, the distance covered by a photon is also quite limited. As well as the lifetime of a photon. Unlikely to exceed 1-2 light minutes.A photon loses energy "overcoming" gravity, In other words when climbing out of a gravity well. But it gains energy falling into a gravity well. Light leaving the surface of a planet will red-shift as it climbs away from the planet. But another observer, at some distance away on another planet sitting in an equally deep gravity well will see no red-shift in the light coming from the first planet, because the light blue-shifted as it fell into his gravity well. The strength of each planet's gravity makes no difference, neither does the distance between them. All that matters is the relative depth of the gravity wells for source and observer.
Spectrum redshift = gravitational constant * distance covered by light.
Definition*. The lifetime of a unit of wave oscillations (one wave) is inversely proportional to the speed of their propagation (or directly proportional to the inertia of the medium) and is directly proportional to the power of their source.
* - this definition is correct with or without the aether.
Space is almost empty, but despite this, thousands of meteors burn out in the earth's atmosphere in just one night? None of the rovers recorded a single meteorite fall on the surface of Mars, given that its official size is not much smaller than that of Earth, and the atmosphere is much thinner than Earth's. That is, much more meteorites should reach the surface of Mars, including objects of such sizes that burn up in the earth's atmosphere.
No, they haven't. 10% to 15% of galaxies are elliptical. And the old idea that elliptical galaxies evolve into spiral galaxies has been rejected.
Bonus; it seems all galaxies have flatten out, why didn't the universe?
Hi all.As with most apparent "paradoxes" in Relativity, this one is likely due to only focusing on one aspect of the theory and ignoring the rest.
Does anyone have some knowledge or insight about this "paradox" in the theory of Relativity?
Imagine a submarine underwater.
The submarine is at rest relative to the fluid and has adjusted it's tanks so that it has equal density with the fluid and remains at a depth of 100 metres. (No thrust required from the engines, it just has neutral buoyancy).
The submarine accelerates rapidly to reach relativistic speeds (let's say 0.9 c) relative to the fluid and then sustains a constant velocity. This is intended to be a horizontal motion, the fins, bow planes etc. were not set to drive the submarine up or down.
As is usual for these sorts of paradoxes, we have two observers in two different frames of reference.
The submarine commander is at rest inside the submarine. She should observe length contraction for the fluid in her rest frame and a corresponding increase in density of the fluid. The submarine retains it's rest characteristics, including density in her frame.
A mermaid is at rest on the ocean floor. In her rest frame, the density of the fluid has not changed, however the submarine has undergone length contraction in her frame and it's density has increased.
Will the submarine rise or sink due to buoyancy?
Background info: You may like to read the Wikipedia article about Supplee's paradox.
There is also a similar discussion about a Helium balloon moving through air on another forum. (I'm not sure I should put links to another forum).
I do not know the answer. I can see references to articles in that Wikipedia entry but they seem to demand some application of General Relativity and a complete re-write of the Archimedian principle. I was wondering if there is a resolution based only on Special Relativity - but I'll take any insight or discussion I can get.
A few corrections here:Why is the Moon moving away from the Earth. Shouldn't it be getting closer, pulled towards the Earth by gravity?
Earth isn't a perfect sphere, it's oblate (more like an egg than a good round ball). The moon is actually causing most of this deformity in the earth (by pulling on it with the force of gravity). The thing is the earth is spinning on it's own axis quite fast, so these bulges get pulled slightly forward of the line between the earth and the moon. The moon goes in a prograde orbit around the earth (it moves around the earth in the same direction as the earth spins). The bulges on the earths surface are then ever so slightly pulling the moon forward a bit, while at the same time slowing the rotation of the earth. By giving the moon a bit more of a pull in the direction tangential to it's orbit the moon's speed is increasing. As that speed increases, the moon drifts out a bit further to an orbit with a greater radius.
There's some info here:
Okay, while it is true that you could maintain a situation of simulated gravity by accelerating a rocket at 9.8m/s^2, our present technology makes it impractical.
Thanks All for All Responses.
Please feel free to continue detailed discussions.
(Personally my Query stands Resolved)
Speed of 9.8 m/s/s would be 35.27 km/hr.
To maintain the Rate of Acceleration, would mean to keep going faster per sec by 9.8 m/s/s.
1 Hour = 60 Mins = 3600secs.
So 1sec at 9.8 m/s..2sec at 19.6 m/s..& so on.
Hence value of 35280 m/s attained.
So that would be 127008 km/hr.
So after an Hour, maintaining the Rate of Acceleration, an object would attain a Speed value of 127008 km/hr.
Just to be reassured i Understand this...
If the clause was for 2 Hours.
Then 7200secs ◊ 9.8 = 70560 m/s.
That's 254016 km/hr.(Speed)
Follow up Question :-
Would a Rocket Accelerating at 9.8 m/s in Deep Space devoid of Any Gravitational Fields be able to mimic the " g " effect on planet Earth?
P.S. - Perhaps a 10 meters cloth(fabric) could be converted into, or better let's say could be assumed to have an approx weight in kilogrammes.
( But Yes i do Completely Understand the Futility of trying to convert " g " into " s ". )
The equation for orbital period is T = 2pi sqrt(a^3/G(m1+m2)Where did all this new angular momentum come from?No new angular momentum. That's part of the discussion, like the skater's arms or a coalsescing galaxy: change the mass distribution and the rotational speed changes.We're mining the moon, not mining the Earth. g (the gravitational acceleration at lunar radius) is unaffected by the mining of the moon.True, but it's another way of changing the weight of the moon, and the one (the OP said "any change...") that would alter R.
Let's compare this scenario to waves created by a ship moving in a pond. Scenario presented on your animations shows a situation, where a wave is propagating perpendicuralry to the motion of a boat in a pond, which moves together with the boat in relation to a stationary observer - it propagates perpendicularly in the frame of boat and diagonally in the frame of stationary observer. However wave propagating perpendicuralry to a moving boat in a stationary pond will behave differently - it will propagate perpendicularly to the moving boat in the frame of stationary bystander and diagonally in the frame of the boat.
If the motion of light is not affected by the motion of it's source in the frame of a stationary observer, then it's the second option (with stationary pond), which should be applied to this scenario.
I'm going to add a couple of animations of my own to try and clarify what is going on here:
I have also an issue with the animation from wikipedia: https://en.wikipedia.org/wiki/Aberration_(astronomy)
According to it light behaves just like any other physical object (e.g a bullet) and the perpendicular motion of the light source is being added to the vector of light propagation - so motion of the light beam is a sum of 2 perpendicular vectors. However as I said earlier motion of the light source shouldn't affect the motion path of light in stationary frame.
I know, that it doesn't have too much with the gravity, but since we're talking about a scenario with the elevator, I wonder what would happen if we would modify it and place the sensor inside the moving elevator, while keeping the source of light in stationary frame. Let's say, that light is being emitted by the stationary source in the moment, when it is at the same level, as the sensor placed inside the elevator moving upwards - will the light reach that sensor or not? If it won't reach it, then the motion of elevator will become absolute/definitive, what will violate the relative nature of relative motion. If it will reach the sensor, then path of light will become curved upwards in the frame of stationary source. Which option is the valid one?Let's, for the moment, exclude the acceleration of the Elevator, and just imagine the path of the light if the Elevator and external light source have a relative motion with respect to each other. Light entering the hole from the source will not hit the sensor opposite the hole. However, you cannot conclude from this that there is absolute motion on the part of the Elevator. This is due the the aberration of light, which is caused by the Relative motion between source and Elevator. It happens exactly the same whether you consider the Elevator moving and the source stationary or the Elevator stationary and the Source moving. Thus it can only tell you that they are moving relative to each other, and not which one is "really" moving.