Relativity

do 2dimensional particles exist? i have heard about something called strings [sub-atomic] which they say are 2d

EM fields are mediated by virtual photons. And, photons cannot escape BHs. So, how can BHs generate EM fields ?

Twin Paradox: Lets assume infinite space. Each twin is on a platform situated side by side to each other. In the original paradox, one twin(b) is propelled at near-lighspeed away from the other twin(a). As twin(a) you are stationary, and 50years has passed, twin(b) returns and has only aged 25 years. But when in reference you can also claim that: twin(b) was stationary, and twin(a) had been the one that left and return. as twin(b) you will have experienced waited 50years for twin(a)'s return. How can this be? In one world we have twin(a) aging twice as much at the time of reunion and in the other we have the opposite, though both events are one and …

Its a basic Physics law that mass can neither be created nor destroyed.But the BBT(Big Bang Theory) defies this law.Big Bang created mass and as a result we are here.That means Big Bang defies the very basic law of Physics.So one thing has to be incorrect.Either the BBT or the basic law of Physics!Thats what confuses me. What do you guys think?

Black holes and the ultimate fate of massive stars is predicted by GR,is backed up by indirect observation and is more-or-less generally accepted fact. I have always wondered about other effects and their plausability, and maybe some of the members ( DrR where are you ? ) who are better versed in GR than I am can provide some guidance. Consider an arrangement of massive stars all going supernova at the exact same time, and collapsing to black holes at the same time ( I know, not possible, but humour me ). At the moment the Swartzchild radius is reached, a massive gravity wave leaves each collapsing star. Now imagine that the arrangement of the original stars is such…

I thought about it, and those experiments with time dilation use clocks, but clocks aren't measuring time, they are just counting the number of times a quartz crystal vibrates or the number of times a gear turns of gears that turn. So, wouldn't a dent in the fabric of space make it tick slower since it would be a higher force of gravity being put in the gears which means that the same amount of energy won't make something travel the same amount of distance in time? So, how does time itself actually effect a quartz crystal vibrating? Shouldn't the effect of a dent in the fabric of space just be that because there's a high force of gravity, that it's harder for the quar…

I was pondering today whilst reading an article on the announcement that the UK atomic clock is the most accurate in the world. Well given einsteins theory of relativity time slows down the with velocity If the earth is moving at about 60, 000 mph, the solar system is travelling at 559,000 mph doe that mean that time experienced on this planet is not a true universal time if you could stop all movement in the universe would that give a true time measurment All as gravity bends space the gravity of the re earth should also impact time. Is this correct or is my thinking wrong

I'm trying to wrap my head around GR, and one thing I've noticed with every EM or quantum eqn I've encountered can be written in the form: (curvature+a bit)Potential/vector potential=source (except dirac, although dirac solutions are a subset of solutions to one like it) Also reformulating newtonian gravity to be SR invariant gives an equation very much like Maxwell's equation (ie. the weak field approximations up to a couple of constants I couldn't track down). Ignoring cosmological constant for the moment. Does anyone know if Einstein's field equations can be written in a form a bit like (I apologise for mangling notation) [math] [\nabla_\mu,\nabla_nu]_{\alpha\be…

As we see in this video at 1:00 the moons gravity well is very small, hardly extending towards the Earth. So then how does the moon pull on the Earth?

I don't know if this has been done already because I don't know what to search for in the find, but, why wouldn't a photon appear to be traveling at 1.5 times the speed of light if you were moving in the exact opposite direction at exactly half the speed of light? Doesn't that defy a principal of relativity?

I know wormhole travel is supposed to be theoretical and unproven, but what is the explanation by proponents of wormhole travel for the fact that the "instantaneous" movement from one space to another has frames in the past, therefore sending information not only back into the past but also making the universe at that moment of time have more energy than it did previously? Or did I misunderstand something? Sorry about my English. It's not my first language.

Is there a frame of reference that is an object itself? Because to something like a bullet, it would only contain a specific amount of energy no matter who was observing it form where, yet speed and energy seem to always be relative. To a bullet, doesn't it have to have a specific amount of energy to travel at a specific speed that its traveling to from another frame of reference.

This was intended as a post in the thread bon spacetime in special relativity. However the forum software (or me) resulted in the piece being superimposed over the initial post, much editing and extreme confusion. So here it is in a separate thread. It is self-contained and therefore a bit redundant to the spacetime thread. The purpose is to show why "proper time" defined in terms of the "spacetime interval" has anything to do with what clocks measure. This explanation is based on a geometric treatment of special relativity. It is largely based on the treatment given in the book The Geometry of Minkowski Space time by Gregory L. Naber. You can refer to that boo…

An external observer will never see an infalling observer cross the event horizon of a black hole - instead the infalling observer will appear to be stationary above the event horizon forever. But how does the infalling observer see the external observer??? I contend that the infalling observer will see the external observer normally - just the way any observer would see another in somewhat flat space. Until the infalling observer crosses the event horizon and then all contact is lost.

I think mass and energy are proportional only when momentum is zero. I doubt it if there is a satisfactory definition of mass or energy in GR that works in all cases.

Since the latest explanation by the Hong Kong scientist confirming the speed of light constant upholding Einstein's speed of light postulate, which states that nothing can go faster than the speed of light and conversely light can go no slower than its constant speed. My question for anyone (or obviously an expert) is how can the speed of light be explained within a black hole? If precisely the speed of light according to the viewers stance arrives at a "dead stop" once it is captured by the black hole's grasp. Anyone please explain this so it can make perfect sense (in words and examples please) to the mathematically ignorant and for that instance to everyone.

The whole relativity depends upon the speed of light which is totally electromagnetic. And, photons only do move with the speed of light at a certain space-time position. Is this strange somewhat? Or, photons do move with the upper limit of relativity, speed of light and why?

Equivalence principle: is it exact? If yes, then why A. Einstein put more than one mathematical model for the GR in the beginning and waited for the proof? And, what about the negative sign that seems to have reversed the meaning of the Equivalence principle, as asked by many scientists?

To my previous question, whether light pulse acquires transverse velocity of the source, there was no answer. Therefore in this post I will assume both the possibilities. Consider a spaceship moving with some velocity, which we will consider as zero. Spaceship is in the frame O1. Observer in the spaceship arranges a source that can direct a light pulse in the direction perpendicular to the length of the spaceship. He arranges a detector D at the top to receive the pulse. Spaceship is now accelerated lengthwise to the new velocity v, which the observer detects on his instrument. Now he is in frame O2. He again sends the pulse. Will the pulse miss the detector?…

Another forum banned me for wishing to discuss this topic, so here I am

If Einsteinian relativity is true -- mass approaches infinity as any mass approaches light speed , how can black holes exist & accrete matter as any mass approaching the Shwartzchild radius would have infinite mass & no length . Infinity is infinity .

Equation for time dilation is, dT= dT’ *Gamma From a space station M, two spaceships depart for a space voyage and they turn around to return at their mid periods. Gamma for spaceship S1 is 1.5 and it sets for a total time of 2 years as measured on its own clock. Gamma for spaceship S2 is 2 and it sets for a total time of 2 years as per its clock. On their return S1 should find that M-clock shows 3 years and S2 should find that it reads 4 years. How can it be?

There are many experiments that prove that light emitted by the moving source does not acquire velocity of the source. Only one I know is that of binary star. However in this it is proved that when the star moves in the direction of our sight or away from it, velocity of light is not c+v or c-v. What is not given is that when the star moves across the line of sight, still it will not acquire velocity of the source. In short photons emitted by the star in the direction perpendicular to the motion of the star will not move along with the star. If this was not the case then we would miss the photons and we will not be able to see the star when it is moving perpendicular …

if you separate one part of a quantum pair and keep it on earth and accelerate the other one to near c, will the one remaining on earth get smaller and more massive?

I'm in a discussion on another forum. The topic is relativity and length contraction. I'm trying to explain to someone that anyone who measures something moving will also measure length contraction. This was meant to correct a common misconception about relativity - that since certain measurable quantities dilate as one's speed increases (time slows down, length contracts, mass increases), those quantities would have to seem to dilate in the opposite direction from the point of view of the one moving. In the case of this discussion, my interlocuter assumed that if someone traveling in a spaceship close to the speed of light undergoes length contraction, then relative to h…