Why does speed time slow down when you go fast then the speed of light

[Guest yamum]

I was woundering why time slows down when you go faster then the speed of light

[NSX]

Due to the consequences of special relativity.

[Guest Sgt Lex]

First of all, Einstein predicted that c (light speed) is the ultimate velocity. Nothing in the universe travels faster than light! So, time slows down ONLY as an observer approaches the speed of light. Here's how it works:

 

Imagine that an observer could travel 99% of the speed of light. We assume that the observer can now study the beam of light more easily, because now the light is only travelling 1% faster, right? Wrong! Light will continue to travel 100% faster than the observer, because light travels at a constant rate relative to us, despite our best efforts to try and catch it up! Here's how time slows down: to the observer travelling at 99% the speed of light, everything seems normal. His clocks will tick at a regular rate of one second per second, and his experiments will yield the expected results. But because he observes light to be travelling at the constant c, we are led to the conclusion that time has slowed down for him!

 

In short, we conclude that time slows down for objects travelling near the speed of light, because it explains how light continues to travel at it's constant rate, despite the speed of the observer relative to it. Sound strange? Almost unbelievably, it's all been verified experimentally.

[Guest Unanswered]

yeah weird :?

[john5746]

Actually, time slows down with any acceleration. Atomic clocks aboard planes have different readings when compared to those on the ground. The difference is very small, so we don't notice in everyday life.

 

Gravity warps space-time. Satellites orbiting the earth are actually accelerating towards the earth. So time slows with Gravity also.

 

Relativity says we can never exceed the speed of light, time slows so much that it becomes impossible. At the speed of light, you would be instantly transported to your destination, because time would not exist for you. How can you exceed an instant?

[Edward]

I am not sure I understand. If I was traking A one light year trip (yes I understand that a llightyear is distance) From point A to point B and the Date when I depart is Jan 1, 2005 and I go at 99% the speed of light from start to finish when I arrive the date will be ~Jan 1, 2006 but my watsh will say ~Jan 1, 2005. Is this right?

 

P.S. I don't understand why I cant go faster than light, if I accelerate towards the speed of light what stops me from going faster than that?

[Duke]

Speed is distance over time. If time is slowing down when you approach the speed of light, then essentialy you are moving at a slower speed.

[J'Dona]

I am not sure I understand. If I was traking A one light year trip (yes I understand that a llightyear is distance) From point A to point B and the Date when I depart is Jan 1' date=' 2005 and I go at 99% the speed of light from start to finish when I arrive the date will be ~Jan 1, 2006 but my watsh will say ~Jan 1, 2005. Is this right?

 

P.S. I don't understand why I cant go faster than light, if I accelerate towards the speed of light what stops me from going faster than that?[/quote']Pretty much; at 99% of the speed of light time dilates by about a factor of seven, so just under two months will have passed. But yes, you watch would have passed less time than clocks on Earth. As john5746 pointed out, this is actually observed in real life, though in space it's mostly due to the satellites travelling at speeds in excess of several miles per second.

 

As for your second point, the reason it's impossiuble for an object to travel faster than the speed of light is because - if that object has mass - its mass increases depending on its velocity until such a point that it would be infinite at the speed of light. Here's the formula:

 

 

You'll notice that when v = c, the denominator is zero, so you're dividing by zero. This doesn't necessarily equal infinity, but in the process of getting there the mass keeps increasing and increasing, so it's impossible because you can never get enough kinetic energy to reach the speed of light.

[swansont]

Actually' date=' time slows down with any acceleration. Atomic clocks aboard planes have different readings when compared to those on the ground. The difference is very small, so we don't notice in everyday life.

 

Gravity warps space-time. Satellites orbiting the earth are actually accelerating towards the earth. So time slows with Gravity also.

 

Relativity says we can never exceed the speed of light, time slows so much that it becomes impossible. At the speed of light, you would be instantly transported to your destination, because time would not exist for you. How can you exceed an instant?[/quote']

 

There are two effects to consider. One is the motion (kinetic potential), which gives time dilation. The second is the gravitational potential, which also gives a redshift or dilation effect.

 

Clocks in gravitational fields run slower as the potential is stronger, and moving clocks run slow, as compared to an inertial observer.

[Dave]

As for your second point, the reason it's impossiuble for an object to travel faster than the speed of light is because - if that object has mass - its mass increases depending on its velocity until such a point that it would be infinite at the speed of light.

 

Not necessarily. For v=c, then this is certainly true, but for v>c, we get complex solutions to the equation. So it may be possible to travel faster than light for particles with imaginary mass - whatever that may mean.

[antimatter]

Time slows down with any accelleration.

It's not very noticeable on Earth because we never reach the speeds at which time slowing down becomes appreciable.

[swansont]

Time slows down with any accelleration.

It's not very noticeable on Earth because we never reach the speeds at which time slowing down becomes appreciable.

 

It's speed, not acceleration, that is the source of time dilation in special relativity. And an acceleration could speed time up, if the acceleration slows you down (i.e. a and v in opposite directions)

 

 

 

(I'm sure that for some reference frame these posts are almost simultaneous, but in ours that was a three-and-a-half year-old thread.)

[antimatter]

It's speed, not acceleration, that is the source of time dilation in special relativity. And an acceleration could speed time up, if the acceleration slows you down (i.e. a and v in opposite directions)

 

 

 

(I'm sure that for some reference frame these posts are almost simultaneous, but in ours that was a three-and-a-half year-old thread.)

 

 

Not only is it speed, but it's also with velocity. I'm not entirely sure that accelleration can in fact slow you down. The term accelleration means an increase of speed.

You are correct in what you said though.

[Cap'n Refsmmat]

The term accelleration means an increase of speed.

No, it means a change in speed.

[antimatter]

No, it means a change in speed.

Yes, that may be true, but I was meaning it in the sense of an increase in speed.

Let's not cling to words here.

[Janus]

No, it means a change in speed.

 

No, it means a change in velocity.

[Cap'n Refsmmat]

Yes, that may be true, but I was meaning it in the sense of an increase in speed.

Let's not cling to words here.

If we're going to talk physics, let's use the accepted physics definitions of words.

 

No, it means a change in velocity.

Whoops, sorry.

[antimatter]

Actually, time slows down with any acceleration. Atomic clocks aboard planes have different readings when compared to those on the ground. The difference is very small, so we don't notice in everyday life.

 

Gravity warps space-time. Satellites orbiting the earth are actually accelerating towards the earth. So time slows with Gravity also.

 

Relativity says we can never exceed the speed of light, time slows so much that it becomes impossible. At the speed of light, you would be instantly transported to your destination, because time would not exist for you. How can you exceed an instant?

We can't reach the speed of light because the amount of energy it would take is just tremendous.

 

I am not entirely sure what you mean of how gravity warps space-time, can you explain?

[Klaynos]

We can't reach the speed of light because the amount of energy it would take is just tremendous.

 

Infinite...

[swansont]

I am not entirely sure what you mean of how gravity warps space-time, can you explain?

 

In the presence of mass and energy, the description of space is no longer Euclidean. What we think of as straight or flat is actually described by a curve. And you can't tell easily, because it actually looks flat — you have to look under special conditions to see the effect.

 

In a way, it's a little like refraction bending light. If you wanted to explain it geometrically, so that the light always went in a straight line, the geometry would no longer be flat.

[antimatter]

Ah okay thanks, that makes more sense to me now.

And so gravity causes this curve in space-time but how does that affect time?

[swansont]

Space time is space + time. They're linked. When you affect one, you affect the other.

[antimatter]

Ah okay, thanks.

[NYSportsGuy]

Everyone just hold on a second. A lot of what is being said here is because you are just assuming what Einstein said was true. I just read a book describing how time is supposed to "slow down" as you travel faster and faster towards the speed of light but in reality..... that doesn't seem to be the case.

 

Time only "slows" down to the person tracking your time on Earth, but not for the person on the spaceship moving at the speed of light of .5c (whatever) you're on.....the observer's time on earth stays constant but that observer clocks your time on the ship to be slower. However the person on board the space ship's clock ISN'T REALLY SLOWER! It is still going the normal time accorrding to his perception....so therefore time really ISN'T slowing down for the person on board the spaceship going at c or .5c.

 

To REPHRASE: The time it takes for the light or the movements of the person on board the ship traveling at .5c or c to hit the stationary observer's eye on Earth gets longer and longer exponentially as the ship goes farther and farther away form the observer on Earth. So technically, you (the observer) see what they do on spaceship a lot longer than when they ACTAULLY DID IT.....hence time appears "slower" to you on earth, but for the people on the spaceship, time is the same for the person traveling at c.

[Janus]

Everyone just hold on a second. A lot of what is being said here is because you are just assuming what Einstein said was true. I just read a book describing how time is supposed to "slow down" as you travel faster and faster towards the speed of light but in reality..... that doesn't seem to be the case.

 

Time only "slows" down to the person tracking your time on Earth, but not for the person on the spaceship moving at the speed of light of .5c (whatever) you're on.....the observer's time on earth stays constant but that observer clocks your time on the ship to be slower. However the person on board the space ship's clock ISN'T REALLY SLOWER! It is still going the normal time accorrding to his perception....so therefore time really ISN'T slowing down for the person on board the spaceship going at c or .5c.

 

To REPHRASE: The time it takes for the light or the movements of the person on board the ship traveling at .5c or c to hit the stationary observer's eye on Earth gets longer and longer exponentially as the ship goes farther and farther away form the observer on Earth. So technically, you (the observer) see what they do on spaceship a lot longer than when they ACTAULLY DID IT.....hence time appears "slower" to you on earth, but for the people on the spaceship, time is the same for the person traveling at c.

 

You've seemed to confuse Doppler shift for time dilation.

 

It is Doppler shift that accounts for the "slowing down" of the other clock you would see due to increasing distance. The flip side of Doppler shift is that with decreasing distance you would see a "speeding up" of the other's clock. Just taking Doppler shift into account, if a ship traveled away from you at .5c, traveled for a distance of 1 ly, turned around and returned at .5c, then you would see him age more slowly on the outbound leg and more quickly on the inbound leg. The upshot being that you meet up again would have seen him age a total of 4 years, while you also aged 4 years.

 

Time dilation (as per Relativity), OTOH is what the time difference is after you factor out the time it takes light to travel from the other ship to you. With time dilation during the same trip, after you meet up again you would have seen the other person as having aged only 3.46 years during the time you aged 4 years. IOW after traveling to a distance of 1 ly and back at 0.5c, the person in the ship will be only 2.46 yrs older than he was when he left, while you wil be 4 yrs older.