Proper time Definition and 155 Threads

Unfortunately I didn't find a thread discussing this issue. First I will sketch the standard argument that one should not use the rocket engine and try to accelerate away from the singularity. Then I will try to identify the problematic part of this argument and ask for your comments. 1) For...

If you are observing a particle enter a black hole, you watch its proper time go to zero at the event horizon as it is 'frozen' there from your frame of reference. What happens in your reference frame as the black hole evaporates? While you can't illuminate where the particle is from your frame...

Dear all, I'm having confusion about the standard derivation of Schwarzschild's gravitational time dilation. For concreteness I'll follow the explanation of Schutz' "gravity from the ground up", but other texts argue the same. So let me rephrase Schutz's explanation (I surpress factors of c in...

In special relativity, we know, (proper time)^{2} = - (proper distance)^{2}. But, in Causal Dynamical Triangulations (CDT), they introduce an asymmetry parameter \alpha as, (proper time)^{2} = - \alpha (proper distance)^{2} [Q. 1] Can you please explain me about, why we need to introduce \alpha...

This may be a dumb question, but some of these other thread got me wondering: is there a concept of local/proper time for electromagnetic waves? I imagine the only 'clock' that could measure time (ticks) at the speed of light would be the field oscillations.

Currently reading the following document which is a bit of a brain overload at the minute! Im considering Equation (4.61). It is the general relativistic correction due to the Schwarzschild field for a near Earth satellite when the parameters \beta, \;\gamma \equiv 1. However, as you will...

Homework Statement Question attached My method was going to be: set ##r=R## and solve for ##n(R)## set ##r=2GM## and solve for ##n(2GM)## I was then going to integrate proper time ##s## over these values of ##r##: ##\int\limits^{n=cos^{-1}(\frac{4GM}{R}-1)}_{n=cos^{-1}(1)=0} s(n) dn ###...

Hello everyone, I have a homework question for general relativity that is driving me nuts. It goes like this: An observer falls from rest at radius 10GM in the spacetime of a black-hole of mass M (in natural units). What time does it take for them to travel from a radius of 6GM to 4GM...

As I understand it, the proper time, ##\tau##, between to events in spacetime is defined in terms of the spacetime interval ##ds^{2}=\eta_{\mu\nu}dx^{\mu}dx^{\nu}##, such that $$d\tau =\sqrt{-ds^{2}}$$ (where we are using the "mostly +" signature with ##c=1##). Now, for time-like intervals, for...

Hi, I am working my way thought Hartle's Gravity. In Section 5.4 he states that "The straight lines along which free particles move in spacetime are paths of longest proper time" and proceeds to proof that "in flat space time the proper time is a curve of extremal proper time". Can someone...

Homework Statement Suppose a spaceship starts from rest from a space station floating in deep space and accelerates at a rate of |a| relative to the space station for 1.0 Ms. It then decelerates for the same amount of time at the same constant rate |a| to arrive at rest at another space station...

It is customary, when discussing a particle's motion through spacetime, to talk about its path x^{\mu}(\lambda) , where x^{\mu} are the the spacetime coordinates of the particle in some frame, and \lambda is some parameter. I have a doubt regarding this parameter. Everywhere I've looked...

Apologies if this is a really stupid question, but what is the exact argument for why one can use proper time to parametrise timelike curves? Is it simply that the arclength of a timelike curve is its elapsed proper time and hence we are simply parametrising the curve by its arclength? Also, is...

Hello! Got a bit of an issue with thew two above mentioned equations about time. From the Lorentz transformation t' = [t - (vx)/c^2]/lorentz factor, we get that the time read by a moving observer for an event in the stationary observer's frame of reference will always be slower (longer) because...

Hi guys, I'm having trouble understanding the definition of proper time interval, according to my book (Physics for scientists and engineers with modrn physics 10th edition serway jewett) the proper time interval "is the time interval between two events measured by an observer who sees the...

Homework Statement Alice is driving a race car around an essentially circular track at a constant speed of 60 m/s. Brian, who is sitting at a fixed position at the edge of the track, measures the time that Alice takes to complete a lap by starting his watch when Alice passes by his position...

So, I've been working through "Exploring Black Holes: Introduction to General Relativity" by Taylor and Wheeler, and I'm somewhat puzzled by a term in the "Rain Frame." The "Rain Frame" is meant to be a frame of reference of an object initially released from rest at infinity as it free-falls...

Dear PF Forum, I'm sorry if I ask the basic question here again. Just need confirmation. V = 0.6; Gamma = 1.25 TRAVEL travels at 0.6c. STAY stays. Pic 02 is Pic 01 boosted -V. 1. All STAY knows about TRAVEL is: Proper Time Speed Is this true? And mutually for TRAVEL 2. At B (and C)...

Can I ask a question here? What is proper distance? V = 0.6c What is proper distance for Blue? What is proper distance for Green? Thanks.

I'm reading An Intro to GR, Hughston and Tod, it says that in GR the idea is that the geometry of st varies from point to point, represented by allowing the metric to vary over space-time. It uses a (+,-,-,-) signature and so ##proper time=ds^{2}##. It then makes the comment that proper time...

Some sources have ##ds^{2}=d\tau^{2} ##, and others have ##ds^{2}=-d\tau^{2}##, Does the sign depend on the signature chosen for the metric? Thanks in advance.

It would be better with a clear example to understand

Is the use of proper time just for ease of simple equations? ie you could define velocity and acceleration with any reference time you want but all other choices are arbitrary other than proper time- proper time is the only time that is special. It seems to me that if you use proper time then...

This is a conceptual problem, right out of a book. Say Mavis is moving in a spaceship at 0.6c relative to Stanley on earth. When Mavis just passes earth, both of them start their clocks. When Mavis reads 0.4s, what does Stanley read on his? Now here's the problem. I think 0.4s being proper...

Is there a way to map time-like curves in Minkowski space to curves in a Euclidean space such that the length of the curve in the Euclidean space is equal to the proper time of the curve in Minkowski space?

Hi all, What is the difference between Lorentz transformations and yt?. That is, the Lorentz transformations for moving between two reference frames are not the same as the relativistic ones. For example considering a frame F that is stationary and an inertial frame F' with velocity v. Time...

Hello. I'm having trouble figuring out from which perspective to measure the proper time interval for Special Relativity. In the textbook, the definition says it's "the time interval between two events measured by an observer who sees the events occur at the same point in space." But in the...

Hi, I know there are already other posts about extremal aging, but all of them are actually closed and none of them is actually answering to my doubt. I've just started T&W "exploring black holes", and I just faced the "extremal aging" principle. Actually, this concept doesn't fit very well...

Two questions, based on the same situation: in http://physics.stackexchange.com/questions/34204/relativistic-acceleration-equation (question A) it is mentioned that, for an object with a constant acceleration g_{M}, and with \tau_{0} =1/g_{M} , after proper time \tau, the coordinates are...

Hi guys, In a scientific paper, I have found the following sentence: "...given the fact that the system is homogeneous in energy, or equivalently, that it has no proper time scale." I'm not sure about what the authors intend to say (what is the relation between being homogeneous in...

In GR one of the fundamental postulates is that ##-ds^2 = - g_{\mu \nu} dx^\mu dx^\nu## is interpreted as a the time on the clock of an observer of constant spatial coordinates; a comoving observer. How does this translate to higher dimensional theories of gravity? There one has a higher...

hi everyone. I'm having trouble understanding the concept of proper time in general relativity. suppose we have some metric given by a fixed mass distribution, say schwarzschild or something (it's not important) and a test particle go over some path between two events A and B. if we want...

Hi In the Schwarzschild metric, the proper time is given by c^{2}dτ^{2} = (1- \frac{2\Phi}{c^2})c^2 dt^2 - r^2 dθ^2 with where \Phi is the gravitational potential. I have left out the d\phi and dr terms. If there is a particle moving in a circle of radius R at constant angular velocity ω...

I have just started studying Special Relativity in class and the concepts of Proper Length and Proper Time are giving me some issues. I understand the basics of length contraction and time dilation, but the idea of this "proper" time and length is giving me problems. One example in particular...

I'm having a hard time figuring out in problems which is proper time and which is just time, and I think it follows from my misunderstanding of time dilation. I've read my book and looked over my notes but I can't seem to figure it out. Here's an example: A person in frame S' moves with a...

The course this question comes from is Modern Physics Homework Statement What is the proper time interval between two events if in some inertial reference frame the events are separated by 109m and 5s? Homework Equations I looked through my notes and under a the sub topic "Invariant...

If an object is orbiting on a circular time-like geodesic path around a mass then the Wikipedia claims that the first component of its four-velocity is given by \frac{dt}{d\tau} = \frac{1}{\sqrt{1-\frac{3}{2}\cdot \frac{r_0}{r}}} where r_0 is the Schwarzschild radius. Is this right and how...

As I've red, we can measure the proper time of an object with a clock that is at rest with respect to the object. So, how would we measure the proper time of an object that is partially moving and partiall at rest. For instance if I'm moving my head and the rest of my body is at rest, how would...

Hi, I hope asking in right forum. I'm trying to understand proper time concept but I'm afraid couldn't understand the reason of answer for below question. "Figure 37-18 shows two clocks in stationary frame S (they are syncronized in that frame) and one clock in moving frame S'. Clocks...

Hello friends, If we consider ##{T}## as coordinate time and ##{\tau}## as proper time, the relationship between them is: ##\frac{T}{\tau}= \frac{1}{\sqrt{1-\frac{v^2}{c^2}}}## so, ##{T}= \frac{\tau}{\sqrt{1-\frac{v^2}{c^2}}}## So we can consider this expression like this: If In...

Can anyone explain proper time with a simple example analogous to real life please? I am having a problem understanding it. Thank you

Hi guys, I'm confused with proper time. Because t=t0 * lambda, proper time t0 is usually smaller than the relativistic time right? Also, proper time is measured by an observer whose frame of reference is at rest right? (Can it be measured by an observer in an inertial frame of reference? Like...

Hi there. 1. The problem statement I am asked to write the equations which give us the mass of a black hole as function the proper time. Homework Equations The Schwarzschild metrics is given by $$ ds^2=-(1- \frac{2GM}{r})dt^2+(1-\frac{2GM}{r})^{-1}dr^2+ r^2(d\theta^2+ \sin^2(\theta)...

As an observer who is simply traveling with the Hubble flow is my proper time the same as the cosmological time or is it equal to the conformal time?

Homework Statement I have written everything in the attachement, please read it Homework Equations I have written everything in the attachement, please read it all of them :) The Attempt at a Solution My solution is also at the PDF attached, just check for correctness, and if i...

please read this problem "An astronaut traveling in a spaceship aims his flashlight to an object inside the spaceship, the beam of light moves on the same direction as the direction of motion of the ship, he observed the time interval between the light leaves the flashlight and when it hits...

We know, when m=0, the schwarzschild space time becomes lorentz space time. Then, the proper time taken by one twin (A) to travel around the massive body in lorentz space while the other twin at rest can not be defined or it will be infinite. Is that true?

"A" starts a journey from a massive body in Schwarzschild geometry in a radial path and returns back to the starting point while "B" stays at rest. Please explain how to find the proper time of "A".

Could anyone explain how Δs is related to the proper time interval?

(a) Write down the definition of proper time and explain how to use the appropriate formula with an example. (b) Write down the definition of proper length and explain how to use the appropriate formula with an example. (c) At what relative speed does a clock move if it runs at a rate that...