Relativity

Hello My name is alejandro, I study physics in Chile. Now i have to do my thesis. My course of general relativity you were guided for the text " a firtz course of general relativity of Bernard Schutz". Do you recommend some theme for my thesis to me? I want a theoretic theme and very advanced no, since my knowledge are not very advanced. I want a mathematical theme pertaining to general relativity Thanks post data: i dont speak english very well

A few questions popped up while reading answers in the other thread related to black holes. I then looked up schwarzschild radius, and even more questions popped up -- hope someone can oblige. 1) Is a black hole's radius smaller than an elementary particle or atom's radius? 2) Gravity is supposed to be the weakest force. Yet a black hole is pretty damn strong. Light can't even escape it. Therefore, if the other forces are stronger than gravity, can each one prevent light from escaping too? 3) Once the schwarzschild radius is fulfilled, the ensuing collapse of mass is unstoppable by any known force. How is that possible if the other forces are stronger …

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Assume you have a rocketship in outer space pointing in an irrelevant direction, and will start to accelerate instantaneously with the creation of an enormous mass. It would travel at a tangent with the mass's limit of gravitational attraction or a random far ut point within the mass's gravitational reach. Now, according to general relativity in contrat to Newtons theory of Gravity light travels faster than gravity, which confirms that gravity has a finite velocity. We also assume that the rocketship and mass are perfectly calibrated to have the rocket pass the mass without being affected by the gravity i.e. general relativity. So if the situatioon held the rocketship wou…

I was hoping someone could answer this question for me, seeing as I have very little of a physics and mathematics background. Let's say a thousand years from now I build a ship that can travel at 99% the speed of light. For every day I spend on the ship, traveling at this speed, how many days pass on earth? Thanks....

This may be somewhat difficult to explain so try to think it through. What if the universe did not expand outwards creating new matter beyond us (outwards of the big bang epicenter), but new matter was 'produced' in the center of the universe (hypothetical center) and pushed all exsisting matter outwards. This would make it difficult for us to recognize an expanding universe, because everything would be traveling at a relative velocity to us. when I say that I mean the exsisting universe as a whole moving relative to us, although seperate bodies may move freely through the expaning universe. I hope this was understandable.

we cannot observe any event before light coming from that point reaches our eyes. so how can we measure the relative velocity between any reference frame & light? & how can we say this remains constant?

Note title.

Is it possible to obtain the Lorentz transformation out of the velocity addition formula ?

Motion cannot take place without time. It should thus be clear that the big bang and the evolution of the universe could not have taken place without time. Time must thus be coinsided as an essential element of the universe. Time has traditionally been expressed in terms of units read out by instruments used to measure it – seconds, minutes etc. Its underlying nature has appeared to escape a good definition. Time as I see it is the force that maintains the present i.e. “now”. I propose that it marches on or progresses at a uniform rate from the big bang constituting a universal time and ageing of the universe. This universal time cannot be read by clocks which may run…

if relative speed of light is constant for all reference frames- suppose there are two light sources one moving with a speed of light itself. now light emitted from them fall on a shooter simultaneously & gets reflected to a stationary observer now since the velocity of light was c wrt the person moving with the speed of light it must be 2c wrt the stationary 1. if not the stationary observer can calculate the vel of light as 0 for the source moves with velocity c itself. again if the vel is 2c for him he can observe the same event the shooter firing twice. for one of the lights travel faster. i cant understand. can light really be emitted then? if not what's stoppi…

Regarding Gravitational Time Dilation, according to N.D. Mermin (It's About Time, pg. 176), In a uniform Gravitational Field, the lower clock runs slower than the upper one by precisely the factor 1 + g D / c2. This has, seemingly, an intriguing Semi-Classical interpretation. For, let us see what "equivalent velocity" would produce the same Time Dilation factor: [math]\gamma \equiv 1 + g \; D / c^{2}[/math] Multiplying both sides by the Rest Energy of the Test Particle, w.h.t.: [math]E_{0} + KE = \gamma \; m \; c^{2} = m \; c^{2} + m \; g \; D = E_{0} + \Delta U_{g}[/math] Thus, the lower clock ticks slower by the same amount it would, if all of its addition…

we suppose some events are occuring outside a reference frame which is moving with speed of light. what will the person inside the frame observe? everything occuring simultaneously or nothing occuring? both cases relate to 0 time interval. pls reply.

Consider the Reissner-Nordstrom GR metric solution for a charge mass-point. This is a free-space solution assuming those two characteristics are "vanishingly small" as to the region of divergence. We see the expected term in m/r; also we see the electric term in G/r^2, which we may interpret as the gravitation effect of the homogeneous (r^-2) electric field energy density. Thus people say it is not possible to understand mass! I assume a near-field inhomogeneity which is not bound to this relationship, and I am working to show an inhomogeneous solution where such a field produces the 1/r term.

Can a singularity and the big crunch be related from a former Universe ?. I believe that our universe changed hands many times.

if length is defined to be nothing but some times a standard length only then why 2 people one moving with respect to the other measures differently the distance between two points? previous answers i got from people is that it is so for the concept of simultanity differs to the two people. what i dont get is what it's got to do with length? if we cannot understand two distance to be same if light doesnt reach our eyes simultaneously then what if we are having a continuous source of light? two light rays started at different times may reach our eyes at the same time even when we r moving. how do we know they started the same time? my question may be stupid its just …

Is space-time something or is it simply a background used to mesure thing ? At first, I was thinking that it was just a mathematical construct used as a background to mesure thing, but now I am not so sure. Spacetime has some property permetivity and permeability. Also it can be bent, it can be draged by spninning body and may have other property that I am not aware off. That make me think that it is something, that it's not only a mathematical construct. Then the universe is composed of matter, energy and spacetime. If it is correct to think about spacetime as something then what is the difference with the old theorie of aether ? Thanks in advance for your answers.

I know very little about relativity, but i have a situation that conflicts with what i've read on the internet. If you were sitting on a planet one light year away from earth and busted out your portable radio and tuned into an earth broadcast, you would be hearing the broadcast as it was one year ago. Now if you hopped in your spaceship and blasted back to earth at nearly the speed of light so that the journey would take one year and a day while listening to your radio, how would the broadcast play? I don't think it would play twice as fast because light measures the same speed no matter how fast you're moving. My theory is that the radio would play at normal speed, whil…

Thoughts on this comment. Where mass exists some of the energy associated with the space has been converted to mass so with a more massive object more space energy has been converted to mass. I believe this can explain gravity. Effectively, space is stretched by the presence of matter, so the plank length is longer in relation to massless space.

I am rhyming to make my case! Ok i'll stop that. I was under the impression before that space inherently grid or point like. I am starting to get from what I read here that this is not true. Is because space has no specific point of reference? Like is space just...space where things happen? Lets say you had nothing but space...could you pick a specific point and that point have any relevance to another point? How is that possible if matter can interact with it? Is interact a bad word to describe the relationship? I get that there are mathematical models of space, are they more representations of how space behaves rather than an exact description of space? …

Hope someone can help me out with this. Does relativity mean that, due to the general expansion of the universe, time in different points in space passes at different rates? Ie: since distant galaxies are racing away from us at a significant fraction of the speed of light, will the rate of time passing in those galaxies be different than it is here? Consider the hypothetical situation of a 'galactic empire' (as in any number of sci-fi universes). Would systems within that empire get out of sync due to this effect or is relativity not even a factor here? What about signals passing between distant systems, would there be appreciable frequency shift due to this ef…

What are the difference between mass and weight?

I have been interested in science my whole life, but got no education, and I have therefore lots of questions I don't get to ask anyone. I try here with some of the questions I wonder about the most, and I hope you have the time to help me. First about the gravitational attraction between objects: Will an object in orbit gradually slow down its speed due to gravitation, and eventually hit the object which is pulling on it? For example the moon in its orbit around the earth. Has the moons speed been grater earlier in time? What keeps the electron in its orbit around the nucleus? There must be some kind of force pushing it forward, or else it would get sucked in by …

I read Lajtner's Time of Time Theory. (Details on http://www.lajtner.com .) He states, time has time and energy and lacks dimension. Therefore there is no time travel. Hova

According to SR a body moving through space contracts in the direction of the velocity. Approaching the speed this can be substantial. It is questioned what damage this might do to a spaceman? His brain and other organs are not designed to function in a distorted condition nor at an increased density.