Relativity

When we are stationary relative to each other, I see a (very) distant beacon flashing once per second. Is it correct please that if I move towards this source at high speed (say 1/2c) I perceive the flashes to be faster ; and that this a consequence of both TD and RD ? Conversely, moving away the beacon appears to slow down ? I would like then to envisage a scenario (gedankexperiment) where TD only comes into play - if this is possible ? Thank you

Hello, the Kerr solution implies a few interesting effects, but I don't understand all of them completly. So I've some questions about the black holes: 1. The frame-dragging-effect implies the rotation (in directon of the black hole angular momentum) of every object in the ergosphere. But what about the conservation of angular momentum if the object has a angular momentum in the other direction as the black hole? Would the difference be taken by the black hole? 2. A object which passes the event horizon need a finite proper time for this. But a infinite far observer wouldn't see that the object passes the event horizon. But if the observer doesn't see this, …

Does time pass in SR? Rietdjik(1967)-Putnam(1968)-Sider (2001) Petkov (2006) ..Russell, Penrose and others, claim that SR proves "Eternalism". That is; The world is an eternal (a-temporal) 4-dimensional spacetime manifold in which all events exist and the notion of passage of time, in other words a moving Now (a global hyper-surface of simultaneous "now events") moving towards the future is a psychological illusion. To quote Geroch; There is no dynamics within space-time itself: nothing ever moves therein; nothing happens; nothing changes[...] one does not think of particles as ‘moving through’ space-time, or as ‘following along’ their world-lines. Rather, particl…

Maybe someone proficient in Relativity can point out what I'm missing here. According to the equations, time slows down when closer to a massive object. That's from an outsiders perspective since time doesn't change from ones own perspective. Also there's a length contraction closer to a massive object. I haven't found any solid answers regarding any possible change in the speed of light when closer to a massive object. I believe an outside observer sees no change in the speed of light, or does it. So then how is the following example explained. We have light bouncing back and forth between two mirrors. Each time the light reflects there's a click being broadcast so …

In the mid-1800s there was a widespread belief that light was moving in a elastic ether. The idea was that space may possess an elastic property. Let’s (as a thought experiment) assume that the elastic property of space is responsible for the curvature of space. We know that the gravitational field of the Earth follows the movement of Earth, ....so if the ether and the gravitation field of earth are made of the same elastic “stuff” there are simply no collision with the ether and the earth, right ? How sure can we by that it was correct to reject the existence of a ether back in 1887? Next year, - time dilation measurements. - on board the ISS will, - definitive wi…

Hi I am new to this and am edger to learn This is a basic concept I am having a hard time understanding (please bear with me I know this a basic concept) When a object falls of a high building, is the reason it accelerates towards the ground at 9.8m/s (ignoring wind resistance in this case) because: : the object is following a geodesic in curved space towards the ground : As the object gets closer to the ground gravity becomes stronger and time is realistically slower (gravitational time dilation) :However the velocity of the object is conserved since no force is acting upon it (it is in free fall) :However since the object is covering the same dis…

Could it be that when a scale speeds up in space? That the reason its mass is increased ,is because it is running into gravity that is counter balancing the balance of gravity. Resulting in reacting against the scale causing the scale to gain more mass. In explanation the gravity in the space that the scale is moving into staying in balance with the scale, reacting together is where the energy comes from. In example ,the space the moon is in is effected by the earths gravity. While the space that earths ocean tides are effected in our effected by the moons gravity. So with gravity counter balancing one space with another space in this reaction. Could one not assume? That…

Is time a dimension without any past or present or future? Does one move through it at the rate of one second per second? That is to say the same rate as the second hand ticking on a clock is also the same rate one experiences time in real time? Is there a reason why the three arrows of time [ biological / thermodynamic / cosmological ] move in only the one direction? Why is the Second Law Of Thermodynamics the one major one that is actually non reversible from a temporal perspective? Is time what space expands into? What happens to time once it passes the event horizon? Does it speed up or slow down? Or stay just the same? How is it possible for a photon not to ex…

In Special relativity, the relativity of simultaneity and absence of an absolute time makes synchronization of clocks a conventional procedure, and therefore prevents from having a measurable one-way speed of light independent of the convention of simultaneity chosen. By choosing Einstein's standard synchronization we get the one-way speed of light equal to the measurable round-trip speed. The issue I have with this is that it would seem like the second postulate of invariance of the speed of light seems to impose(by the postulated isotropy of space) that the only valid synchronization is Einstein's, wich would be incompatible with the conventionality of synchroniza…

So, I've been thinking a little recently. I've had this idea in my head that I feel is probably wrong, but I'd like some insight into why it's wrong if that be the case. So let me explain... I understand that objects moving at very high rates of speed experience time dilation. A clock aboard a spaceship moving at a high rate of speed will tick slower than one sitting stationary on earth. So, in theory, someone who boards a hypothetical spaceship could move at a very high rate of speed over an extended period of time and exit with less time being passed on his body than what has been experienced by the outside world. Thus being time travel. However, I've been doing som…

Since the observable universe is expanding at the speed of light, (ie we can see a light second per second distance into the currently unobservable universe), yet the universes expansion is thought to be accelerating due to dark energy, does this mean we can extrapolate to a point where the size of the observable universe reaches a limit? (because the accelerated expansion makes the outer reaches of the observable universe again expand away from us faster than the speed of light) What happens beyond this point? Do we see the universe we observed at the fringes frozen in time and this freezing of time spread back towards us as the observable universe shrinks due to the ac…

I was just wondering what would change in the results of the schwarzschild metric if the time coordinate was instead measured at a finite distance from the massive body, rather than the infinite distance it is currently placed at. How would the results vary as the finite distance increased or decreased?

Zitterbewegung is the hypothetical rapid trembling motion of subatomic particles, which is sporadic in different directions and could be thought of more or less as occurring in every direction due to how rapid the sporadic changes in direction are. If it exists, it would supposedly be caused by fluctuations in positive and negative fields around/nearby the particle, such as from other particles, and this would mean that Zitterbewegung becomes more intense when particles are grouped together. So, if we assume Zitterbewegung exists as a property of all matter and all of those facts about it are true, it would end up producing an effect very similar to gravity would it n…

Trying to get more information. I've already looked into it somewhat. I noticed: after eyeballing the equation in that other thread, I am but still trying to wrap my head around all the ins and outs. Rapidity is of particular interest, not sure I have a clear understanding as of yet.

When photons cross a black holes event horizon we say it means they can never been seen again by anyone outside it. Does a photon then: A) Travel forever towards the center of the black hole, never quite reaching it. B) Travel in a finite ammount of time towards the center and stays there for an infinite ammount of time. C) Travel to the center and continue outwards for an infinite ammount of time never crossing the event horizon again. Does it make a difference to an outside observer?

Classical calculated with Newton the escape speed is r = 2G.M/v2. With black holes and v = c that would be r = 2G.M/c2. That is the same as the Scharzschild radius calculated with relativity. Does that mean that Newton laws are still valid at this radius?

Observers are at distance each from other on axis 'x'. Accelerating spaceship travels lengthways of axis 'x'. Is the spaceship length contracting to center of the spaceship relative to the observers or somehow differently?

I've been thinking about gravity and its curving effect on spacetime. It seems very strange to me that a massive object can warp space and time around it. I have a few questions: 1. Would a magnetic field as strong as the gravity around a black hole bend the spacetime around it? If so, it's the bending effect same as that of gravity? 2. If gravity is a curvature in spacetime, and not a force, why doesn't the centre of an object experience the same curvature? (for eg, Fg=0 at the centre of the earth)as I thought it is because the forces cancel out each other at the centre.

Over the years I have read a lot about Black Holes (BH) and the associated Event Horizon (EH). Two statements about black holes strike me as worringly in contention with each other and they lead to a conclusion that seems to make the traditional BH a mockery. Here we go..... According to accounts I have read by various notables (such as Stephen Hawking and Kip Thorne) these two statements stand out: Statement 1. An outside observer watching an object fall into a BH will never see it cross the EH. The explanantion is that the light from the object will become redshifted the closer it gets to the EH and we will simply not get any visible light back from it. Tha…

is the movie interstellar correct about Time Dilation

Consider 2 separate systems of masses; A and B, C and D. B,C and D are all the same mass. A is some mass a lot smaller than the others. The only gravitational influence is from the masses within in each system. Assuming the edge of each mass is lined up the same as in the image, will the two systems make contact at the same time?

Is the momentum=gamma *speed of center of their masses*(mass of the Earth+mass of the Moon) Or the momentum=gamma *speed of center of their masses *(mass of the Earth+mass of the Moon+ + kinetic energy of the Moon relatively of the Earth / c2)

Hey Guys! First time poster here. I've had this question for a while now and I can't seem to find the answer online. So whenever relativity and time dilation is explained they start out by saying that there is no absolute motion, objects only move in relation to each other. The very next thing you see if that "one person is standing still, while another is moving close to the speed of light..." which directly contradicts the first point. If one person is "standing still" and another is "traveling near light speed" but there is no absolute motion, only motion is relation to each other, then it is just as valid to say that the person who was "standing still" w…

I've read there are studies that if you increase a system's energy while keeping it's mass constant, it's gravity increases. That increase is very small (related to E/(c^2)), insignificant on testable and relative scales, but perhaps significant at quantum scales (when rc < 1). Point being, if changes in energy effects gravity while mass is constant, energy should be a variable in formulating gravity.

Time is different throughout the universe. I think there is a common moment of now because something happening everywhere. The question is what makes time different if there is a common moment of now since the beginning of the Universe? Is it the combined effect of space and gravity? Isnt´t time a firm information and space, speed, gravitational effects differes? Share your thoughts.