Time is defined operationally to be that which is measured by clocks. The SI unit of time is the second, which is defined to be

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74 views

What is the longitudinal difference between the sub­solar point and the magnetic poles at time $t$ (hours)?

I'm trying to convert geomagnetic coordinate to geographic, but there are some steps in the paper which I'm reading, that I don't understand. I have the geomagnetic latitude centered around the ...
0
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0answers
84 views

Calculating impact velocity and time with non-uniform acceleration [duplicate]

Here goes: imagine a spacecraft with engines shut off in a free fall towards some celestial body x. let's say the distance to surface is $100 000$ $\text{meters}$. initial vertical velocity is ...
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0answers
35 views

Is aging independent of time progression when relativistic effects are taken into account? [duplicate]

I have been trying to understand Einstein's principle of relativity for quite some time. I have at least I believe, understood the notion that time is relative and can actually 'change' relative to ...
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3answers
320 views

Do photons see shorter distances due to space contraction?

I may be wrong, but this is just what I've heard. People often talk about what would happen if we, humans, were able to make a spaceship travel at the speed of light. If I'm not mistaken, then we ...
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0answers
44 views

A Global Measure on a Gravitational System

I am a computer science engineer and I am trying to simulate the gravity on my computer; several objects with different masses randomly distributed in a Three-dimensional space. I would like to ...
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0answers
65 views

What “time” is it for or on Voyager 1? If you could be “still” in the Universe who fast would time be? [duplicate]

I just sent this to JPL but am not putting all my eggs in one basket so thought I would try some other clever people. :-) I think about physics and space quite a lot but I'm not a maths genius so do ...
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0answers
38 views

Does the direction of perceived time depend on location in the universe?

Do the laws of physics allow for the possibility that in a galaxy far far away, the perceived arrow of time is in the opposite direction to ours, where people (aliens) die before they are born, and ...
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1answer
161 views

Did physicists solve the grandfather paradox? [duplicate]

Now, physicists are trying to send information backward in time. But, why are physicists almost sure that this would happen and why are they so confident about it? Did physicists solve the grandfather ...
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0answers
33 views

Is the universe immediately dependent upon the past? [duplicate]

Given complete knowledge of the precise state of every property of every particle and energy phenomenon existing in our universe for a given infinitely small frame of time, is it possible to ...
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0answers
44 views

Calculate age of the Universe at 7 billion and 28 billion years old [duplicate]

If $1 / H_0 $ is about 14 billion years, then what happened when the universe was half its current age? Is the empirically determined $H_0$ supposed to have been twice its current value? And when ...
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0answers
48 views

What happens with time at the speed of light? [duplicate]

Say that by some means you could become massless, and therefore travel at the speed of light. I understand that the closer you get to the speed of light, the slower time appears to the person ...
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0answers
194 views

What about continuity of Space and possible discreteness of Time? [duplicate]

Is time continuous or discrete? Is even this question a valid question? If you say, it all depends on resolution then assume the best possible resolution achievable. If it is discrete, then what about ...
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0answers
141 views

What is difference between $\frac {dr}{dt}$ and $\frac {\partial r}{\partial t}$? [duplicate]

What is difference in physical meaning of partial time derivative and ordinary derivative of $r$? $$\frac {\partial r}{\partial t}\quad\text{and}\quad \frac {dr}{dt}.$$ I know that ordinary time ...
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0answers
46 views

Estimating the present state of stars [duplicate]

Many time while reading through astronomy articles on the stars most of then thousand of light years away from earth. I have wondered how do astronomer know about the present state of star if we are ...
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0answers
35 views

What is the formula for calculating the length of any given day (sunrise to sunset)? [duplicate]

In a specific date what law gives us perfect measurements and how will we measure if latitude is given?
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2answers
88 views

How was time defined before we knew the speed of light was constant or in classical physics? [closed]

Nowadays, we now about $c$ the universal speed of light. This lets us define the notion of distance in terms of time (despite the fact that it works the opposite way for our common units.) Before ...
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1answer
80 views

How do we presently understand time?

How do we presently understand time? Can a second be related directly to physical phenomena? What is a second really? Why are we sure that time is linear?
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2answers
179 views

How could mass exist before Big Bang?

I heard that before Big Bang the temperatures were so high that mass and energy constantly converted to each other. After big bang the temperature became less and the conversion stopped that is what ...
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3answers
265 views

According to relativity, can a statement be true and false in same time?

Say I write following statement on a paper: It's year 2014 at earth. Then I give it to my friend. My friend then starts to leave me and earth to outside with velocity of light. Einstein says the ...
-1
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1answer
193 views

Is time an illusion? [closed]

IS time an illusion? I have tried thought experiment after TE and quite frankly I can't find any instance where time is defined wholly on its own. It is always a measurement of the interim between to ...
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5answers
2k views

2 balls falling hit the ground at the same time

There are 2 balls in a vacuum, next to each other but not touch. They are on the edge of a surface they will both leave the table at exactly the same time. One gets pushed harder than the other. The ...
-1
votes
2answers
57 views

Relativity asymmetry?

If you have two bodies that move towards each other at a constant velocity, each body will observe the other body experience time faster. This does not make sense to me because if you had a person ...
-1
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1answer
1k views

What is the difference between UT0, UT1 and GMT time?

Every reference I find says that they are "essentially" the same, which we all know really means that they are not the same, but different only by a some small amount that someone else other than me ...
-1
votes
1answer
179 views

Could time be changing without us knowing? [closed]

I've been wondering about relativity for a while now. We seem to measure time by using the speed of light. Light can be slowed down or stopped We assume light doesn't change in a vacuum - yet, how ...
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1answer
175 views

US time zones and Daylight saving time, energy efficient? [closed]

As a foreigner, United States has a very complex time system for me. Central Time Zone, North American Eastern Time Zone, ...
-1
votes
1answer
45 views

Find Distance with Acceleration and Time

I'm working on Physics homework and have run into a problem I can't figure out. Any help would be much appreciated! Problem: Allison exerts a steady net force of 50N on a 22-kg shopping cart ...
-1
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1answer
157 views

Determine the distance from time-velocity graph [duplicate]

A small car that we made in class was travelling and its time was recorded at 1,2,3, and 4 meters. The points in the form (seconds, meters) are as follows: ...
-1
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1answer
87 views

What is the formula for determining time dilation (as the object in motion)? [duplicate]

The formula for calculating how much time passes for a still observer is T=TO/(1-v^2/c^2)^1/2. How do I calculate what TO is?
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2answers
134 views

Backward Time Flow?

Physicists say that time is moving foward because entropy always increases. But have physicists considered that we might be mistaken? Since there is no ultimate reference frame, it could be possible ...
-1
votes
1answer
75 views

Is the universe we know just shaped due to time? [closed]

Call me a daydreamer, but I could not stop myself for asking this question. I was idle when something ticked me and struck my head. I was thinking about universe, speed of light, and how time works. ...
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votes
1answer
212 views

Calculate time to go from one point to another point [closed]

in a 2D football game I want to calculate cycle(time) until ball go from one point to another point. in this link exist all fomulas that we need for my problem but anyone does not have any parameter ...
-1
votes
1answer
73 views

Does the movement of things in the universe will cease one day?

To start or change the movement, we need a force. This force, according to Newton's second law, is variation of quantity of motion from the object per unit of time.Therefore, if the variation does not ...
-1
votes
1answer
234 views

length, width, and time

is it possible to have length, width and time. A 2D or 1D object with the 4th dimension (although then there would not be 4 dimensions so would it b 3D?) .
-1
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1answer
50 views

Time and gravity relation

I was reading about relativity when I crossed by the applications of relativity in real life, and they said that as the elevation increase time increase so gravity decrease Can someone explain to me, ...
-1
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2answers
48 views

Can I sum-up time?

If a kinetic process takes 1 second to complete(reach a point), and that process is repeated $n$ number of times, is this formula correct $t_t$=$n\times 1$ = total time in seconds? It's similar to a ...
-1
votes
1answer
41 views

Time dilation: reference frame [closed]

So I'm calculating how long it will take for half of some muons to decay for in a stationary observers frame of reference. They have a half life of 2.2 * 10^-6 and are moving at a speed of .98c ...
-1
votes
2answers
164 views

Proof that time exists [duplicate]

Is time just an axiom? Or can it be proven to exist? Correct me if I'm wrong, but our whole understanding of the universe is based on directly observing the world and building out axioms that are ...
-1
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1answer
95 views

Problem related in relative motion [closed]

The speed of a boat is 1.5 m/s in still water. One needs to cross a river of width 500 m with this boat. Along the direction of the river a strong wind is blowing with a speed of 0.9 m/s. The boat is ...
-1
votes
1answer
1k 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?
-1
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1answer
119 views

Displacement inside the moving Object

Suppose say a person is standing over the moving bike and he jumps while bike is moving, bike will move forward & person will land in same point at which he jumped, relative to earth position ...
-1
votes
1answer
585 views

How do photons experience time? [duplicate]

I know that as velocity approaches the speed of light the time dilation shoots to infinity as shown below. 1)So I want to know how time is perceived from the point of view of the photon? 2)Since ...
-1
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1answer
116 views

Existence of time in some other universe [closed]

Is it necessary that time should exist in another universe if it (universe) is there? How do we perceive timelessness?
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2answers
174 views

are clocks always wrong? [closed]

So I was sitting thinking earlier and I remembered an experiment that I heard a couple days back about how scientists put a stop watch on a jet and it had a different time then one on earth because ...
-2
votes
3answers
321 views

How can we be sure about the constancy of atomic clocks as in the Hafele and Keating time dilation test?

Atomic clocks were used in Hafele and Keatings experiment which supposedly helped to prove time dilation. Time Dilation Proof - Hafele and Keating How can we be sure other forces didn't act upon the ...
-2
votes
2answers
385 views

Gravity vs. Velocity Time Dilation [closed]

Can some one give me the unified formula for Gravity Time Dilation and Velocity Time Dilation.
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3answers
1k views

How does Time traveling work in practice?

There are multiple theories about time traveling. One is "proven": The time slows down according to your speed. The satellites in space are traveling faster than us, thus their clocks slows down a ...
-2
votes
3answers
195 views

Is it possible to defy time using speed? [closed]

I have always wondered if we were to travel at past the speed of light (even beyond the current capability) would we be able to slow down time around us? I have asked my teacher at school and he has ...
-2
votes
1answer
203 views

The time is a type of energy ?

You know energy is necessary for the occurrence of an event . Time is also exactly neccessary for the occurrence of an event. If there is no time , there will be no event. I mean time is a type of ...
-2
votes
1answer
99 views

Gravitational Time Dilation Formula? [closed]

What is the equation for calculating the dilation of time at different levels of gravitational force?
-2
votes
3answers
190 views

Is Space conserved [closed]

Can space be created or destroyed? Is space conserved? I am not asking for matter,energy and time. Its just a question about conservation of space PS: I am asking for what was there before big bang. ...