Relativity Definition and 998 Threads

Homework Statement If a spacecraft is traveling to a star which is located at a distance of 1 lightyear and it would take the spacecraft 1 year to reach the star in its own frame, how fast would the spacecraft actually fly? Also, how long would the journey take for an observer on Earth...

There is a relationship between each of the mathematical values in each of the paradoxes with regard to each observers. There is obviously also a relationship between every situation we study in the Special Theory of Relativity. The Lorentz Transformations obviously prove this. So, I began to...

I started this post on physics.stackexchange but it's too vague for that site, so here I am! :) I'm trying to really get the intuition of spacetime. This video explains how Minkoswki was the first to think that maybe our universe does not consist of a 3d space which evolves in time, but rather...

This is probably extremely wrong I just want to know how. If photons don't experience time doesn't that mean they are every where at once, and if that is true doesn't part of quantum physics say before a particle is observed its in all the states it can be in? So doesn't that apply in that sense...

Hi. Thanks for letting me ask this question. It is a stupid one. I'm a newbie at relativity theory, and I'm reading On the electrodynamics of moving bodies, By Einstein, A. He associates time with space, and tells us that you can measure the "time" of an event if you are in the coordinates of...

Good evening. I think I've got it as far as time dilation is concerned. Could someone please let me know if this calculation is correct? - From frame C( stationary camera) Bob is moving at 50,000KM/second parallel to Alice's path - Bob is also 50,000KM behind Alice on the parallel path - Bob's...

The discussion here https://www.physicsforums.com/threads/general-relativity-the-sun-revolves-around-the-earth.245334/ concludes that in general relativity there are no privileged reference frames so that, for example, it would be valid to use the Earth as a reference frame and say that...

I know that c is the same in all reference frames. I am trying to understand the rail car thought experiment. I've got it down pretty well except for one part - the difference between an observer moving toward a light source versus an observer moving away from a light source at the same...

Hi pf, When I was taught about SR, I was told it was one of the most successful theories in science and has been verified over and over again. However, I have been watching some videos online and wanted some guidance. I initially came across this: <link deleted> This guy claims to have a PhD...

This young student won $250K for explaining Relativity http://www.sciencealert.com/a-high-school-student-just-won-250-000-for-explaining-relativity-using-a-pick-up-truck-and-usain-bolt

From Verifying the Theory of Relativity by Chandrasekhar Sir J.J. Thomson, as President of the Royal Society at that time, concluded the meeting with the statement', I have to confess that no one has yet succeeded in stating in clear language what the theory of Einstein's really is'. And...

Homework Statement Two spaceships fly toward a space station as shown in the figure. Relative to the station, spaceship A has speed 0.8c. Relative to the station, what speed is required of spaceship B such that its pilot sees A and the station approach B at the same speed? (a) 0.40c (b) 0.50c...

Homework Statement Homework EquationsThe Attempt at a Solution [/B]Assuming that the relation ## v = \omega r ## is valid in relativistic calculation. As the speed is greater for higher kinetic energy, ## \omega_2 ## is greater. This is shown by only (d). So, I think (d) should...

I need to simulate the Friedman equations under different conditions of flat space. Can someone please tell me a good package in MATLAB, Mathematica or stand alone. I am most well versed in MATLAB but have coded in Mathematica before.

What is the best book to learn general relativity for undergraduate and graduate students ? And why?

I've always read that these two theories are incompatible, and how General Relativity works for large scales while Quantum Theory represent reality in extra-small cases. So my question is where is the limit where General relativity ceases to exist and Quantum Theory gives a better portrait of...

A problem I struggle to conceptualise as I have began leanring about relativity and seek your guidance and knowledge on: Consider a stationary observer at point A. Relative to the observer there is a train traveling at -0.6c. A passenger on board the train has a particle gun, and fires it in...

Hi All, An observer, F, stands on Earth. A spaceship, F', is also on Earth. Their clocks are set at 0. The spaceship then leaves Earth at .5c. After 10 seconds, F sends a light signal to F'. As soon as F' receives the signal, F' sends a light signal back. When does F receive this signal from...

Homework Statement A graduate student discovers that an elementary particle produced in his experiment travels 0.250 mm through the lab at a speed of 0.950c before it decays (becomes another particle). What is the lifetime of the particle measured in its rest frame (proper lifetime). A) 8.77 x...

This is an IB problem from November 2017. Two rockets are separated by 6E8m (2 sec x c, or two light-seconds), w.r.t. Earth, and are approaching Earth from opposite directions. Rocket A approaches from left at 0.6c. Rocket B approaches form right at 0.4c. According to Earth, when do they...

Homework Statement Spaceship A, traveling past us at 0.7c, sends a message capsule to spaceship B, which is in front of A and is traveling in the same direction as A at 0.8c relative to us. The capsule travels at 0.9c relative to us. A clock that measures the proper time between the sending and...

Homework Statement How can we tell that quantum effects do not propagate along forward light-cones that represent two separate events? How do light-cones demonstrate this notion of quantum effects? Homework EquationsThe Attempt at a Solution We don't know which events occur first given...

why is the general theory of relativity is so complicated i feel that it's very simple no thing hard in it there is a whole website to make people understand it i read the articles and i didn't found any thing complicated knowing the i am 13 so it should be very hard to understand

When expanding Kinetic energy as T=mc2-m0c2 where m0=rest mass and m=m0/sqrt(1-β2) the first term correction is coming out to be -p4/8m03c2 but taking T=E-m0c2 where E=sqrt(c^2p^2+m02c4) the correction is coming to be 3p^4/8m03c2 is there any contradiction?

Who agrees with the result? I don't think she was sufficiently rigorous on her explanation. (She won $800.000)

Consider single line motion. If an observer sees two objects, and one is seen moving say 50 m/s faster than the other, will all other observers measure the same velocity difference? The answer seems to be 'No' from the velocity addition formula of special relativity? Thus same velocity...

When we talk about energy scales, we often hear that we need new theories of gravity and particle physics when we hit the barrier that is the Planck scale. In particle physics we've only probed up to about 13TeV, which is way WAY below that level. It's easy for us to designate the energy to...

Can anyone help me with a very basic question please. Is it really not possible for anything to travel faster than the speed of light, as dictated by relativity theory ? I am a complete beginner to Physics and only have very basic mathematics knowledge and I'm trying to understand the basics of...

Hi, If a particle is within 2 m/s of the speed of light (like at CERN) and then more energy is transferred to the particle, where does this energy go? Some sources I have read talk about relativistic mass getting bigger and approaching infinity as a particle approaches 'c'. However, this source...

Superconducting Ring In a superconducting ring does the contraction of space between electrons cause them to move inwards? Like in this animation. Force Between Parallel Wires With Current In the proton frame of two parallel wires with identical current, I've been told they attract and this...

Hi everyone! I'm trying to make a list of recommended books (introductory and advanced). So far, what I was able to search are the following: Particle Physics: - Griffiths: Introduction to Elementary Particles - Thomson: Modern Particle Physics - Nachtmann: Elementary Particle Physics -...

I am having a hard time trying to understand this transformation from lorentz:https://imgur.com/a/WYWMO (You should ignore the spanish part and just focus on the math). I can’t understand well why they turn into what you can see in the second picture, when taking really small values of x...

Homework Statement Homework EquationsThe Attempt at a Solution ok so for w' i am getting since the s' is only moving in x direction ## \omega' = \omega \gamma (1 + \beta) ## is this correct then i am having some trouble in dealing with the dot product to derive for ## \bf {ck'} ##

Homework Statement Consider the metric ds2=(u2-v2)(du2 -dv2). I have to find a coordinate system (t,x), such that ds2=dt2-dx2. The same for the metric: ds2=dv2-v2du2. Homework Equations General coordinate transformation, ds2=gabdxadxb The Attempt at a Solution I started with a general...

One of the founding principles in GR is the principle of general relativity, which loosely states that all coordinate frames (inertial and non-inertial) are equivalent in the sense that the laws of physics are invariant. My question is, does the justification for this come from Einstein's...

I was watching a movie called Everything and Nothing. It got me thinking. For the sake of argument pretend that you could make the sun pop in and out of existence. If you were to measure the distance between two points on the other side of the solar system with no sun, then if the sun were to...

Hi guys, I am new to physics forums and am an undergrad who is really interested in the philosophical implications of quantum physics. I know this isn’t a philosophy forum but upon skimming older threads regarding MWI I have come across an interesting number of posts by a few members named...

I understand that momentum, rest mass and energy can be put on the sides of a right triangle such that the Pythagorean Theorem suggests E^2=p^2+m^2. I understand that the Dirac equation says E=aypy+axpx+azpz+Bm and that when we square both sides the momentum and mass terms square while the cross...

I recently watched this Varitasium video where he explains the magnetic field due to a current carrying wire. In the video he explains how what we see and describe as the magnetic field produced by a current carrying wire is actually just a electric force caused by the an imbalance of charges...

Hi, I read through einsteins popular book on relativity translated into english around 1922 and subsequently read the original 1905 paper on the electrodynamics of moving bodies. So we have a fixed observer seeing flashes happening at the same time and we have a moving observer seeing one...

There are two kind of singularities which are familiar in General Relativity. One of them is the singularity of Black Holes and the other is at the beggining of the universe. I'm confortable with the former singularity --it seems to make sense. But as with the latter, I'm not so confortable...

Please don't kill me here...I am really just a curious creature...QFT and GR are mutually incapabatable ergo they cannot both be correct...so best is that one is used for low energy large scale predictions (as per theory) and small scale high energies ( as part theory) ...(BTW I know what the...

https://arxiv.org/pdf/hep-ph/0609174.pdf page 8. 2.1.2 Special Relativity Requires Antiparticles This article describes a scenario in which atom A releases an electron which is absorbed by atom B. A=> A+ and B => B- However in a different inertial frame (F) it is possible due to Heisenberg's...

A non-moving observer is looking at two different rockets in space. One rocket is moving at a steady velocity of 0.5c, and the other rocket is currently moving in 0.5c but has steadily accelerated from 0.3c and will continue accelerating until it gets to 0.7c. Assuming that there is no...

How can volumes and hypervolumes be related to Einstein's theory of special relativity and to quantum mechanics? Also, can volumes and hypervolumes of objects be used for modeling how different scenarios can change over time? Oh yeah, and hi my name is Sasha Jaffarove!

I thought about the geometry of Earth by definition and thought of the implications of 'curved space-time'. I understand a trajectory of a satellite and other objects to be straight geodesics through warped space-time. Would the Earth then therefore be able to described as a straight surface in...

Imagine that I have a straight, statically-charged, cylinder-shaped tube with arbitrary (ideally infinite) extent. The charge is distributed evenly over the tube such that the field inside the tube is zero. For convenience, let's line up the tube centered along the x-axis such that the...

Homework Statement Homework EquationsThe Attempt at a Solution it is known that ##a_0 ##is the proper acceleration ## a= \frac{a_0}{\gamma^3} ## hence integrating it gets ## v = \frac{a_0t}{\sqrt{1 + (\frac{a_0 t}{c})^2}} ## but this is in terms of t how to make it in terms of t'

Hi guys, A real easy one. Are the following postulates completely true about general relativity as they are pretty amazing to me. 1) Black holes are a solution to his field equations for GR (or are predicted by the theory) 2) His field equations also suggested the universe was expanding 3)...

Homework Statement My textbook states: Since the number of particles of dust is conserved we also have the conservation equation $$\nabla_\mu (\rho u^\mu)=0$$ Where ##\rho=nm=N/(\mathrm{d}x \cdot \mathrm{d}y \cdot \mathrm{d}z) m## is the mass per infinitesimal volume and ## (u^\mu) ## is...