# Can time be stopped ?

#### roger

can time be stopped ? if so how can it be done ?

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#### scott1

According to realtivity if you went faster then the speed of light time would appear to stop.
But I'am not sure if that's what your question is.

#### sweetvirgogirl

scott1 said:
According to realtivity if you went faster then the speed of light time would appear to stop.
But I'am not sure if that's what your question is.
i think it would stop AT the speed of light ....

at a speed faster than light, it would go in reverse direction or something like that

anyway, yeah even I'm not sure in what context you're asking whether time can be stopped

#### roger

i mean stops so that it all freezes.

#### sweetvirgogirl

here's the thing ...

i think ... even if you are traveling at speed of light or greater than that, time in your ref. frame will NOT stop or change direction ...

however ... if you are looking at another person, and you are traveling at speed of light, it will look like the clock s/he has is not ticking at all ... meaning, his/her time has stopped for you...

however, i am not sure if you can stop time in your own ref. frame, so i am not sure whether it is possible to freeze it all ... i dont think current laws in physics allow that ... but then laws in physics change all the time :-/

i hope i didnt confuse you further ...

#### Mk

Not that you could ever be traveling ≥c in the first place.

I don't think we know of any ways we could stop time in the near future, and only a limited amount of possible ways.

#### Hootenanny

Staff Emeritus
Gold Member
According to einstein;

$$E_{k} = \frac{mc^2}{\sqrt{1-\frac{v^2}{c^2}}} - mc^2$$

If we are travelling at the speed of light the term $\frac{v^2}{c^2}$ is one and hence the denomator of the fraction is zero, leading to the first term becoming infinite. Therefore, to travel at the speed of light would require an infinite amount of energy. That's my understanding anyway.

-Hoot

#### scott1

Hootenanny said:
According to einstein;

$$E_{k} = \frac{mc^2}{\sqrt{1-\frac{v^2}{c^2}}} - mc^2$$

If we are travelling at the speed of light the term $\frac{v^2}{c^2}$ is one and hence the denomator of the fraction is zero, leading to the first term becoming infinite. Therefore, to travel at the speed of light would require an infinite amount of energy. That's my understanding anyway.

-Hoot
I don't think that's what his question.He didn't ask would it be possible to stop time but can it be stoped.
i mean stops so that it all freezes.
I think I understand what your asking.Are you asking that time itself stops and everthing in the universe seems to stop no matter how fast your going.

#### roger

Hootenanny said:
According to einstein;

$$E_{k} = \frac{mc^2}{\sqrt{1-\frac{v^2}{c^2}}} - mc^2$$

If we are travelling at the speed of light the term $\frac{v^2}{c^2}$ is one and hence the denomator of the fraction is zero, leading to the first term becoming infinite. Therefore, to travel at the speed of light would require an infinite amount of energy. That's my understanding anyway.

-Hoot
If the denominator was zero, the fraction would be undefined, as far as I understand.Unless you meant tending to zero

#### vanesch

Staff Emeritus
Gold Member
roger said:
can time be stopped ? if so how can it be done ?
Isn't that what stop watches are for ? :shy:
(ok, silly joke...)

#### Hootenanny

Staff Emeritus
Gold Member
roger said:
If the denominator was zero, the fraction would be undefined, as far as I understand.Unless you meant tending to zero
Sorry tending to zero, becuase v would never actually equal c.

#### Mk

I think we need to stay out of this going faster than c thing, we're going in circles.

#### PatPwnt

Time is stopped for photons. They don't experience time. If you could travel the speed of light, it would take you 0 time to travel any distance.

#### hashir

as far as my knowledge goes time cannot be stopped
this is because for time to stop u need to travel at the speed of light. even if u do travel at that speed light always travels relative to ur speed therefore it will be travelling twice as fast.
another way to think of this is:
if u travel at the speed of light and look in the mirror will u be able to see ur self?
because light travels relative to ur speed

#### hurk4

A photon travels at the speed of light. Coming from the sun it will take 8 minutes to arive at the earth. Maybe in its own reference system (what does that mean in the case of a photon?) time stays zero, but in my refence system time did not stop, did it?

#### hurk4

Questioning a bit further on the photon's trip.
I suppose that in its own co moving reference system of a photon, time does not proceed, time did not even begin.
But what is the colour of a blue (in my reference system) photon leaving the sun during its trip to earth in the photon’s reference system? Does it even have a colour of its own in its own reference system and subsequently energy in its own reference system?
And to go a big step further. Did anything happen to the colour of an initially blue cosmic background photon on its 13.6 billion years trip to earth travelling through the extending space arriving finally with a wavelength of 2.7 micrometer? Did anything happen to its energy in its own reference system?

#### bayan

Time my friend is a oneway highway. (heavily traficed I should include.)

even if you were to traver faster than that of light the relative time would still not be reversed, as that simply implies that C is not the Universal Speed Limit. The C in the formula does not just mean Speed of light rather it means universal speed limit.........

having said that there is a way of stoping time. just press the stop on ur stop watch :)

#### vanesch

Staff Emeritus
Gold Member
hurk4 said:
A photon travels at the speed of light. Coming from the sun it will take 8 minutes to arive at the earth. Maybe in its own reference system (what does that mean in the case of a photon?) time stays zero,
In fact, there's no such thing as "the own reference frame" of the photon, because the particularity of something moving at the speed of light is exactly that it moves at the speed of light in ALL reference frames - it is the definition of the conformal structure of spacetime.
So all that can be derived from the use of the "reference frame of the photon" is meaningless, in the same way as it would be meaningless to derive things from the "rational number who squares to two".

#### cmbezln

what about statements coming from string theory researchers, such as:

-the speed of light (photons) is constant...nomatter what direction youre traveling and how fast.

#### Mk

Isn't that what stop watches are for ?
(ok, silly joke...)
You're absolutely terrible.

#### jasc15

PatPwnt said:
Time is stopped for photons. They don't experience time. If you could travel the speed of light, it would take you 0 time to travel any distance.
so if you travelled at c, like a photon, it would take you 0 time to travel any distance, which means that you would be everywhere in the universe at once! which makes sense due to length contraction. of course we are talking about limits where v->c, so it is asymptotic and you would never reach c.

#### Rudolf888

can time be stopped ?

This is a place it st....

King James Bible
And the sun stood still, and the moon stayed, until the people had avenged themselves upon their enemies. [Is] not this written in the book of Jasher? So the sun stood still in the midst of heaven, and hasted not to go down about a whole day

#### JDługosz

i think it would stop AT the speed of light ....

at a speed faster than light, it would go in reverse direction or something like that

anyway, yeah even I'm not sure in what context you're asking whether time can be stopped
Right, at the speed of light time stops.

Traveling faster than light, you could visit events that took place in the past. However, the "proper time" of the moving object becomes an imaginary number so I have no idea what that would do to physical processes experiencing it.

#### granpa

time stops at the event horizon.
it would also seem to stop behind an accelerating rocket (from the point of view of the rocket)
http://math.ucr.edu/home/baez/physics/Relativity/SR/rocket.html [Broken]

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#### AJ_2010

Time is stopped for photons. They don't experience time. If you could travel the speed of light, it would take you 0 time to travel any distance.
So the photons that take 8mins to travel from the sun to earth experience no time?
Even though the time for us to measure them is taking 8mins?

In the 8mins that we observe, what is happening to the photon? Obvious answer is that it is traveling distance. But this raises the statement that to travel a distance you need a velocity and time. (Distance = Velocity/Time)

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