1
vote
2answers
33 views

In terms of physics, does the phrase “time slows down” mean the same thing as “things happen more slowly?”

The common definition of "time" is a type of measurement, like size. But the sentence "size gets bigger" doesn't make any sense. Is "time slows down" an odd phrasing of "events occur more slowly" or ...
2
votes
4answers
86 views

How much could one slow down aging using existing spacecraft?

Imagine that I board a spacecraft and head away from the Earth at top speed until I've aged twenty years, then I turn around and come back. How much younger will I be than the unexciting folk who hung ...
-1
votes
0answers
24 views

Trying to calculate the average speed from this question [on hold]

I already checked the average speed question that was posted before and tried applying the methods to my question but nothing seemed to work. I would like to know if anyone can explain to me how to ...
0
votes
1answer
55 views

How has the age of the Universe been derived from the observations made by the Planck mission?

The parameters of $\rm\Lambda CDM$ model have been determined to an amazing high precision from the measurements made by the Planck mission. In particular, the Hubble "constant" (the value of Hubble ...
2
votes
3answers
46 views

Can we measure rates in real time?

I know what it means to say that my position is "X" at a particular moment in time. I can easily take a picture of my motion and observe my exact location at the instant the picture was taken. That is ...
18
votes
3answers
2k views

Would computers accelerated to high speeds compute “faster” from our point of view?

I woke up to this thought yesterday: Lets say Computers A and B have exactly the same specifications and at time T both are set to process an algorith that would normally take exactly 1 year and ...
3
votes
2answers
169 views

Why time is considered a dimension?

Why time is considered to be a dimension? And the other 7 (except the 3 dimensions of space, and the dimension of time) dimensions that string theory suggests, why can't they be realized?
0
votes
1answer
113 views

Why doesn't light travel instantly? [duplicate]

I've read that the faster you travel in space, the slower you travel in time. And when you reach the speed of light (which we won't be able to) time will stand still. So when light travels at the ...
2
votes
0answers
31 views

Expectation value for the time of a photon reflection

A photon is reflected by matter (by an electron in empty space). How long does the reflection take? (i.e. is there any infinitesimal time elapsing during the reflection process?), or more precisely, ...
-3
votes
0answers
34 views

Is there a place with no time dilation? [duplicate]

It there a theoretical maximum speed of relative time where velocity is zero and gravity is too? Obviously gravity can never be zero and neither can velocity, but what is the closest to this ...
7
votes
3answers
877 views

Why does time stop in black holes?

Everyone says that time stops in the black hole. It's a "fact". However, I have never heard everyone explaining that. Of course, I know that observer in weaker gravitational field sees that something ...
3
votes
2answers
121 views

How can we measure time?

If we cannot define a proper time (or synchronize clocks in different positions) in an inertial frame (independent with the theory of relativity), there seems to be no direct way to confirm the 2 ...
0
votes
3answers
44 views

Why there is added a partial time derivative in formula for time derivative of potential energy? [duplicate]

In proving the total energy in conservative field is constant we have this equation(picture) why it added partial derivative? Why? I mean where it did come from?
2
votes
0answers
41 views

How to prove that a time-oriented spacetime possesses a nowhere vanishing timelike vector field?

Penrose gave a very brief proof to this question. Since the spacetime is paracompact, there exists a positive definite metric called $h_{ab}$. Then, the nowhere vanishing time-like vector field $V^a$ ...
2
votes
1answer
76 views

Relativity of simultaneity and the second law of thermodynamics? [closed]

Has the connection been noted between these two? I have been studying special relativity and in learning Minkowski diagrams I have noticed that as v approaches c, the relativity of simultaneity is so ...
3
votes
0answers
41 views

Does the definition of the SI unit “second” require that possible perturbation of primary frequency standards should be measured?

The definition of the SI unit "second" is stated as The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground ...
8
votes
2answers
111 views

Why do we remember the past but not the future?

The question is sometimes referred to as the "psychological arrow of time" (Hawking, 1985). Here the past is understood as a moment or time when the entropy of the universe was lower, and contrarily ...
1
vote
1answer
58 views

Black holes and Time Dilation at the horizon

What is the difference between proper time and the observer time? Whilst thinking about Black holes, when we see the Schwarzschild metric $$c^2\tau ^2 = \left ( 1 - \frac{r_{s}}{r} \right )c^2t^2 - ...
0
votes
0answers
72 views

Twin Paradox Without Acceleration

So I've been doing a lot of reading about the twin paradox and have encountered several different explanations that strive to resolve it. First off let me start by saying general relativity is not an ...
1
vote
2answers
188 views

Is time subjective?

In Minkowski spacetime time is subjective [or more precisely: time is different for every particle/ reference frame]. It is the coordinate time of an observer whose reference frame travels up the ...
2
votes
2answers
382 views

Why is the second the SI base unit for time?

Specifically, during the moves towards Le Système international d'unités in the 18th and 19th centuries, why didn't anyone attempt to move us away from the definition of there being 24 hours in a day? ...
0
votes
3answers
70 views

Is proper time an intrinsic value of Minkowski space?

What is proper time? Is it a part of Minkowski space (that is a mere spacetime interval)? Or is it an intrinsic characteristic of massive particles (a sort of "aging")? Example: In the following ...
0
votes
1answer
40 views

How is that the life of a virtual particle duo is shorter than Planck Time?

I have always thought that the time is discrete (jumping), not continuous and the shortest time is Planck Time. One reason for that was the information on ...
0
votes
1answer
51 views

How much time passed for the passenger traveling with at speed-of-light spaceship? [duplicate]

Let's suppose we have a spaceship with the exact speed of light. If a traveller takes this spaceship to go to proxima centauri (approximately 4 years light away from Earth) and come back, we (as ...
1
vote
2answers
70 views

Dragon Ball Z: Hyperbolic Time Chamber *(also increased gravity training) [closed]

Firstly, I am sorry if this seems like a joke. It is not. I have always loved the Dragon Ball series, so this question has been on my mind for a while. Can ...
-1
votes
4answers
78 views

Would infinite time elapse relative to an outside observer if an object was completely at rest?

Here's my reasoning... time dilation due to velocity: t'=t√(1-v^2) v expressed as a % of the speed of light. If you are moving through distance at the speed of light, to an observer at rest relative ...
2
votes
1answer
34 views

Lorentz transformation via light clocks in parallel direction

In order to derive the Lorentz transformation one can use the picture of a light clock. A Photons bounces back and forth between two mirrors. This is then observed in two different inertial systems. ...
0
votes
1answer
32 views

Does a light cone only effect the time an object has lived?

I'm confused about light cones and I've driven a crazy scenario to try to represent it. Let's say I can move through my past light cone to the exact time of my birth. If I kept on moving back could ...
-3
votes
1answer
87 views

Does time really exist? [duplicate]

Does time really exist? or is it a human invention and convention? What is the truth? are there time particles? please remember, I'm looking for constructive answers, not condescending and void ones.
0
votes
1answer
56 views

Why does time dilation cause you to age slower? And is time considered relative to the observer?

I understand that the higher your velocity the slower light will move. But how does time itself slow down while you are moving faster?
3
votes
1answer
63 views

Can you calculate unix timestamps (universal clock) from any planet?

Given the definition of unix timestamp as the number of seconds elapsed since January 1st, 1970 as GMT+0, without leap seconds, is it possible to create a universal clock that will generate the ...
1
vote
1answer
30 views

If an area remains at temperature 0 Kelvin would the area be frozen in time?

If an area is at 0 kelvin, I am guessing that there is no motion. Without motion in an area, will it not look as if time has stopped?
10
votes
5answers
474 views

Clocks in special relativity

One book on special relativity says: Any observer at rest relative to his own timepiece will see that other clocks moving with respect to him run fast - the greater their speed, the faster they ...
4
votes
2answers
336 views

What is the duration of a snap?

What is the duration of a snap (of the fingers)? When someone says, "it's ridiculously fast, it's like [snap]" - where [snap] is them snapping their fingers - they would normally mean it is ...
2
votes
1answer
45 views

Does negative energy density (i.e. weak energy condition violation) create closed timelike curves?

I remember reading something about Stephen Hawking denying the fact you can't make CTC's (Closed Timelike Curves) without weak energy condition violation. If this is true, where do the light cones ...
0
votes
1answer
58 views

Is there no fourth dimension (time) in the universe? [closed]

In this article (and numerous others) http://phys.org/news/2011-04-scientists-spacetime-dimension.html and http://www.rebelscience.org/Crackpots/notorious.htm they suggest that there is no time ...
1
vote
1answer
41 views

Travel time for accelerating object [closed]

I have an object which starts at velocity = 0. Accelerates to a known max speed and continues thereon at constant velocity (max speed). My problem: How long does it take to reach a known ...
2
votes
1answer
30 views

What are the units for rate of movement through time? [duplicate]

Thinking of time as the dimension orthogonal to depth, it seems logical that the rate at which a body moves through time could vary. Do units exist for rate of movement through time? The numerator ...
0
votes
3answers
69 views

Am I accelerating in the fourth dimension (time)? [closed]

I have an intuitive feeling that I am accelerating in the fourth dimension. As we get older, we all perceive time moving faster. Are there any arguments or theories in physics which address this ...
0
votes
0answers
30 views

Review and mentions about time discretization

I would like to get basic knowledge in this topic of time discretization, at least basics. Because of I'm new in this field I don't know what is better way to start. Could anybody suggest any reviews ...
2
votes
1answer
45 views

How to get time from equation of linear uniformly accelerated motion?

I have had a problem solving this equation for time (from Linear Uniformly Accelerated Motion (LUAM)): $$ s= v_0t + \tfrac{1}{2}at^2 $$ I'll appreciate if someone could provide me some step-by-step ...
3
votes
2answers
187 views

How is time not a constant?

I am a visual person, so it's hard to imagine the information I keep getting, but shouldn't time be a constant? If you were traveling at the speed of light and your able to cover $299{,}792{,}458$ ...
-3
votes
1answer
82 views

Quantum entanglement and special relativity PARADOX

imagine two entangled atomic clocks , we entangle them and then measure the time , it has to be the same , right ? now lets suppose that we entangle them , but don't measure them, then we plant one ...
3
votes
1answer
106 views

How to interpret $t^2$? [closed]

I can't think of the meaning of squaring the Time (multiplying it by itself). It makes sense in Mathematics. But how can you figure it out in nature (or physics). As an example, the formula ...
2
votes
1answer
113 views

Quantum Field Theory with (2,2) metric

Does someone know some reference which treats QFT in a space with the following non-Lorentzian signature: $g_{\mu\nu}=\text{diag}(-1,-1,1,1)$. I'm interested in basic stuff like the shape of the ...
0
votes
0answers
37 views

How do you determine who is moving “faster” in relativity? [duplicate]

I suspect this question has a simple answer, but I can't get my head around it. The classic example of a person in orbit around the Earth at high speed experiencing a slower passage of time than the ...
4
votes
2answers
170 views

What does it mean to “convert energy into time”?

In a recent article about creating electron-positron pairs by colliding photons in a laboratory, Andrei Seryi, director of the John Adams Institute at Oxford University, was quoted to said: It's ...
1
vote
1answer
76 views

If gravity bends space time, could gravity be manipulated to freeze time? [closed]

You age at a different rate depending on the force of gravity. Astronauts age fractions of fractions of fractions of a second less than earthlings. If you took a sphere of equal masses, separated by ...
-1
votes
2answers
112 views

I understand the Big Bang Theory (BBT), but how was the matter in the BBT created?

I understand the Big Bang Theory to consist of all of the matter being pulled into one great gravitational pull. such a great force that it expelled the matter out causing the idea of Red-Shift and ...
2
votes
1answer
116 views

Do particles travel backward in time in a particle interpretation of field theory?

In this Phys.SE answer Ron Maimon stats: there is no relativistic particle formalism in which the particles have postive energies and casual propagation. You can either deal with fields in which ...