Relativity

My first post! And this is a very paradoxical problem which I am unable to make head or tail. http://galileo.phys....chronizing.html From the above link... We agree that the person on the train observes synch-clocks and on the ground observes non-synch of the two clocks. What if the train comes to a stop and the person on the train brings out the clock to let the person on the ground to have a look. Then which version of the synchronization is correct? I mean what do the two observers see? I know it is not possible for one to see a synch-clock and the other to see non-synch-clock at the same time. What gives?

Gravity is a force. Let's think about this case. When an object move from low gravity planet to very high gravity planet. It's mass is same on two planets. But their energy is very different. The object's energy of the high gravity planet is very high. How can we explain this phenomena with the energy conservation law?

According to the relativity theory the moving object mass should be changed. When we measure the mass at the 273 K and at the 0 K, the two measured mass may have very small difference. Because the electron movement at 0K is very slow. Is this right? If so, which one is the correct mass?

Some difficult question. Mass. When two objects collide, the momentum equation is like this. m1v1 + m1v1 = 2m1v1 Gravity. F= c(m1* m2)/r^2 Why is gravity proportional to mass? mass factor ~= gravity factor in the particular system?? Any good opinion?

I was wondering, with time dilation. If it occurs when an object is moving, no matter how fast, wouldn't that mean that as we ourselves are moving including other objects, everything is constantly being/getting jumbled around in time, That nothing is in phase.. And for my next question, which may be a little philosophical (for this section). If such things as ourselves, 'conscious' beings, perceive "time" and its effects within the context of existence. Could that mean relativity is only accountable for things such as ourselves, since, as 'time' is conveyed through us, in terms of the river of time, its effects can only be interpreted via the system for which it is pe…

We have known and heard about the so-called Time Machine, especially in the cartoon, everyone of us knows the impossibility of the existence of such a thing, but ..... what a time machine? Is a device that creates a gap or take us to the past to the future .. Going to rule out a future to it is practically impossible and theoretically .. But going to the past is it impossible as well? To see what Uncle Einstein said. He said every body is going very fast, the time will slow down with him .. Of course, Uncle Einstein did not ride any machine going in the desired speed, to know that time is slowing or not, but all he has done is a calculation that assured his …

First post here, Hi all. I had thought about this some years ago, but visiting here, this seemed like the place to posit it. Many of you will be familiar, in relativity with the thought experiment of the light bulb in the moving train carriage. The light bulb is in the centre of the carriage, and when turned on, depending on the observer, the light may reach the back of the carriage before the first, or both at the same time, whether you are looking in from an embankment, or sitting inside the carriage respectively. Say we were to take this further... Inside the carriage, on either side are small light sensitive switches, both of which are connected to a b…

I am very new to this site. (couple minutes actually) but i am not new to the concepts of theoretical and quantum physics. I have read a couple beginning books on these topics, but have many more on their way. I have always been extremely interested in these crazy theorems and ideas. I plan on taking a physics related career in my life, and want to begin learning lots about it's expansive information. Anyways, over my readings i have read over the simple equation E=mc^2 many many times. I understand its meaning well enough. E standing for energy. m for mass. and c obviously for the speed of light. This meaning that a very very large amount of energy is stored…

Howdy folks I'm new here. Just another silly question regarding this stuff! I think when I stumble over layman's descriptions of the Theory of Relativity its telling me that light travels past objects at the same speed no matter how the source of the light and the destination are moving in relation to each other which seems insane to me. Am I interpreting this right? And if so.. what would happen in the below scenario? A light is switched on in a vacuum with two moving objects a light second away at that exact time. Object 1 is moving away from the source at 1/3 of the speed of light, and Object 2 is moving away at 2/3 of the speed of light. Surely this theo…

Special relativity says that a clock on a spaceship moving relative to a stationary observer appears to be running more slowly than if it was stationary. So if this is true, what would you get in the following scenario? Stationary observer Andy and moving observer Brian are both initially stationary and in the same location, and each has an atomic clocks measuring time in days, and displaying what they can see on a large monitor visible to both. In addition both clocks emit an electronic "pip" whenever one day passes to the next, and each records the number of pips made since reset. Day = 0, and the pip counter is set to 0. Brian rapidly accelerates towards a dist…

i am 16 so be nice... Today I realized that time is not a constant and there for it is possible that time can be fluxuating without us even realizing it. To us it would seem normal. How ever if someone were watching form a "third person like view" it would be as though we are speeding up and slowing down constantly. I base this on my own intellect and nothing more. Although I could be wrong I feel that it is very possible. If I am right we would have to rewrite equations in order to add in this extra variable.

Hi I have a general understanding of general relativity, but when it comes to equation, I have a very vague idea of the math involved and cannot answer by myself some questions. 1- Does Einsten equation include the space-time expension ? 2- Does the vacuum Einstein equation give an expanding space-time or a static space-time ? Thanks wiki Einstein equation

Consider a spacecraft travelling through the cosmos at a constant high speed, say .87c, and vector. It should be experiencing time dilation to about half normal (stationary) time. Ie, 1 sec to it would be experienced as 2 seconds to all stationary observers regardless of their orientation to the spacecraft. By that I mean regardless whether the observers are behind, beside or ahead of the spacecraft. The craft is broadcasting light and other electro-magnetic radiation from within itself as it is travelling. Because of time dilation this EM radiation would be observed as redshifted by all (stationary to the Cosmos) observers. In addition to this, the fact that it is movi…

I was wondering, if gravity in general relativity is the result of the curvature of space/time. Then how can the effect at the earth surface for which we all feel be accounted for, since space/time is being warped due to our presence on the earths surface is it... Because isn't general relativity only describing the topology of space external to the earth - as in the universe at large..

Just read Hawking and Mllodinow's new book The Grand Design. Very interesting. Although I thought it was way too short, and didn't go into concepts in nearly enough detail. For example, it says that per general relativity: Due to the immense density of the very early universe and thus its stupendous spacetime curvature, time was a 4th dimension of space! As the universe expanded (and its density and spacetime curvature became less), tIme itself was formed out of this 4th space dimension . So based on this, there was no time before the big bang. Can anyone tell me something about how this works? I have read that inside a black hole, time and space switch roles du…

So, i was reading up some article about black holes the other day and a thought struck me. according to relativity, light being bent by gravity is following a straight line on the geodesic(if i'm wrong here then the rest is gibberish) . so, if we havea case where the gravity is strong enough to curve light into a circle, this surface would in effect, be flat. So, black holes are flat from a space-time perspective. so if we then extrapolate this out to the earth, this means the earth is slightly more flat than it would be if it didn't have mass. This effect would of course be tiny for the earth and over-powered by oblateness, terrain and the population density of c…

The reason that there are time paradoxs with special relativity is that Einstein got it part wrong. Which part? In his parable of the train with the light beam bouncing up and down he mistakenly assumed that inside the train was a separate part of space-time to the outside of the train. In fact it is not separate and the observer in the train will see what the outside observer would see.. ie, the light beam zig zagging between the mirrors in the direction the train is coming from, the zig zags becoming greater as the speed increases. So, no time dilation due to speed. However, due to the tremendous input of energy to accelerate the train to near light speed the mass of th…

I would like to offer a context for considering and discussing the principal of Relativity. It is abstract but is derived using an anti-reductionist train of thought (i.e. bottom - up) rather than the conventional top - down. - The Universe has been shown to be Relativistic, however this tends to lead to a unsatisfactory position regarding the basis from which we can derive our starting position. Intuitively, the position would be most easily considered as a consequence of the only Absolutes, namely 0 (nothing) & 1 (Infinity/God, everything) - in Philosophical terms it is often illustrated as the Yin Yang. Our Universe does not contain either, so the inference is…

I have recently has a thought but it might just be a highly simplified version of general relativity...Please explain GR to me without equations in the simplest way possible. A basic summary for it. And don't use this diagram: It makes no sense. Reasons why this diagram is misleading: 1. For it to make an indentation there would have to be something like gravity pulling the sphere down. There isn't as that would mean the entire universe would keep moving down until it hit whatever is the source. An effect like this would surely be visible or traceable in the movement of the stars and planets. 2. The sheet is space-time if I understand correctly. If distortions…

So, some guy is proposing that time has multiple dimensions, instead of just the single "4th dimension" that we are all familiar with. He is not a crackpot, and his stuff predicts and explains small errors apparent in time measurement with clocks aboard GPS satellites. You can get a link to the introduction part here: http://www.stanford.edu/~afmayer/

Short version: Can a space traveler ever observe Earth time appearing to go backward? I claim "no" but under that claim I keep coming around to an inconsistency where more distant things will age more than nearer things. Where am I going wrong? Long version: I'm trying to figure out what is observed by the traveling twin during an extremely fast deceleration + return acceleration phase in the twin paradox. This is also described as the rocket undergoing a frame switch. According to my understanding of what I've read, the traveling twin will see the Earth twin age a large amount in that very short period of rocket time. What happens if the rocket "frame-swit…

Energy has always been defined as a scalar quantity since it measures magnitude but, of course has no direction. (E.g. temperature) And as we know vectors have magnitude and direction. (E.g: Velocity) However, there are 4 dimensions. Our three spacial dimensions and then the fourth: Time. Now as I understand it, everything in the universe is travelling through the fourth dimension at lightspeed. So while energy has no typical direction it has a forwards direction in time. So energy in one place, 3 seconds later, will have traveled forwards (4 dimensionally) by "3 seconds" So isn't energy technically a vector?

I have some trouble reconciling the fact that there is no absolute frame of reference with the fact that forces become apparent when something rotates. Mach's principle seems to be a solution to this problem, and I have a couple of questions about it. First, my understanding of Mach's Principle is that your local inertia is governed in relation to the inertia of everything else that has mass or energy in the universe. Therefore, because everything else in the universe is, on average, in a fixed position position relative to you, you can use 'everything else' as a reference point to tell you whether you are spinning or not and you will feel the forces associated w…

I had this idea that started off crazy but then it started to make some consequences of special relativity seem more intuitive. This is an alternative interpretation of the reality that relativity describes. However, all of the rules for the theory are based on special relativity, specifically so that it doesn't contradict any observations predicted by relativity. So far I haven't run into any problems where the theory falls apart, but I haven't tackled relativistic motion, and I'm not sure whether the theory will fall apart, or if there's even any hope that it could suggest any possible result that is different from relativity (fingers crossed on twin paradox). He…

Hi, This is a complicated one to describe, but it's been driving me and a friend mad for a few days Let's say a train is travelling round the Earth at almost the speed of light, and there is an observer on the train and another at the only train station. Each observer counts how many times he passes the station (i.e. orbits the Earth). The observer at the station says the counting will last for 1 minute, and he starts and stops the train. Let's say the person at the station counted the train pass 400 times in the minute. So far so good, but since the train is travelling close to the speed of light, time will move slower for the train passenger, so after the minu…