Define: Time?

**Stildawn** · September 24, 2012, 11:17 PM

Sorry to sound like an idiot haha, I'm not hard out into science or anything but I find this forum an interesting read from time to time.

But one thing that I see alot in here is this "Time" thing.

I guess I am wrong, but in my logical mind, Time is simply the time (haha) passed between this point and that. Like the time it took me to type this post, it can be measured by any random scale you want to make up etc but its static in my mind. The time to write this post was the same regards of scale, speed or whatever.

But I see alot around here the mention of speed in regards to time. Things like if your travelling the speed of light you age slower... Why? Why would I age slower? The same amount of time however you measure it would have passed if I walked 1 meter in 1 second at walking pace or I traveled 299792458 meters in one second at the speed of light. The time passed measured in seconds was 1. The only difference (in my mind lol) between the two scenarios is that in one I traveled 1 meter and in the other I traveled 299792458 meters.

I've also seen things like "bending time space" etc. WTF? How on earth are you ment to bend time? I didn't know that time was tangible?

So basically I have come to the conclusion that I don't know what time means. As I'm sure all the scientists are alot smarter in these things (and probably most things lets be honest) than I am.

So what the hell does time mean? In laymans terms if possible?

P.s. Hope this post made sense, I find it very hard to formulate this thought process into words haha so bare with me.
P.s.s I also assume I'm going to cop alot of laughter in this question. haha

**Slaytaninc** · September 25, 2012, 12:33 AM

I remember getting involved in a discussion about time on deployment.

**Jack04** · September 25, 2012, 12:42 AM

Time acts like another dimension so, insomuch as distance being the difference between two spatial points, time is the difference between two temporal ones. So far, so good.

The problem comes when you realise that the speed of light is constant in all frames of reference (whether you're travelling towards it, away from it, perpendicular to it...). Consider a light clock:

I hope you'll agree that that is a perfectly valid form of clock. T = 2L/C.

... but now, consider that light clock on a train. You're on the platform, your friend is on the train with it. Because he is in the same reference frame as the clock, he sees it as shown above. However you see:

The light appears to have travelled further in your reference frame than in his. How can this be? The speed of light is identical for both of you, so it cannot have travelled any further or faster in the same time period. The solution is that space and time are malleable, and so you get time dilation and length contraction.

Where:

t' = γt and L' = L/γ

With γ being:

Where β = v/c.

So it turns out that if you're travelling at the speed of light, v/c becomes 1 and the gamma factor tends to infinity. At this point, all distances become effectively zero and all times become infinite (you effectively stop experiencing time).

[/First Year relativity course]

**Stildawn** · September 25, 2012, 03:48 PM

Originally Posted by Jack04

Time acts like another dimension so, insomuch as distance being the difference between two spatial points, time is the difference between two temporal ones. So far, so good.

The problem comes when you realise that the speed of light is constant in all frames of reference (whether you're travelling towards it, away from it, perpendicular to it...). Consider a light clock:

I hope you'll agree that that is a perfectly valid form of clock. T = 2L/C.

... but now, consider that light clock on a train. You're on the platform, your friend is on the train with it. Because he is in the same reference frame as the clock, he sees it as shown above. However you see:

The light appears to have travelled further in your reference frame than in his. How can this be? The speed of light is identical for both of you, so it cannot have travelled any further or faster in the same time period. The solution is that space and time are malleable, and so you get time dilation and length contraction.

Where:

t' = γt and L' = L/γ

With γ being:

Where β = v/c.

So it turns out that if you're travelling at the speed of light, v/c becomes 1 and the gamma factor tends to infinity. At this point, all distances become effectively zero and all times become infinite (you effectively stop experiencing time).

[/First Year relativity course]

I admit I got a bit lost in most of this thread. Especially the last part of this post, I got the first part and correct me if I'm wrong:

So if I can see the clock on the train from where I am standing, the difference between what I see and what my friend does is the time taken for the light (sight) to travel from the clock to my eyes so I can see the time? Just like stars in the night sky the light we see is actually really really old light? Am I on the right path?

I get confused though in regards to the age thing. If I am traveling at the speed of light, surely my body still ages at the same rate regardless of speed, the same rate as it does at normal speeds on earth?

I read in one of the threads in here about space travel and one post said something like "If you traveled at the speed of light to a distination, when you arrived all of your relatives etc would already be dead" (that isn't a direct quote by the way).

Why is that? If that is even true? Or am I reading it wrong?

**Jack04** · September 26, 2012, 10:38 AM

Originally Posted by Stildawn

I admit I got a bit lost in most of this thread. Especially the last part of this post, I got the first part and correct me if I'm wrong:

So if I can see the clock on the train from where I am standing, the difference between what I see and what my friend does is the time taken for the light (sight) to travel from the clock to my eyes so I can see the time? Just like stars in the night sky the light we see is actually really really old light? Am I on the right path?

No, the time taken for the light to travel to your eyes is not relevant. Even if your friend and you were stood exactly the same distance from the clock but your friend was on the train, there would be a disparity. This is because the light is having to do different things in the different frames. In your frame, it is having to move laterally, whilst in his, it is not. Because it is travelling at the same speed in both of your frames of reference, the only solution is that space-time has changed slightly.

I get confused though in regards to the age thing. If I am traveling at the speed of light, surely my body still ages at the same rate regardless of speed, the same rate as it does at normal speeds on earth?

In your frame of reference, yes. However think of it this way: The distance you are travelling becomes zero. So the amount you age whilst travelling at the speed of light is zero. Meanwhile, someone who is not travelling at the speed of light "sees" you travelling at the speed of light over a large distance, whilst not apparently aging.

I read in one of the threads in here about space travel and one post said something like "If you traveled at the speed of light to a distination, when you arrived all of your relatives etc would already be dead" (that isn't a direct quote by the way).

Why is that? If that is even true? Or am I reading it wrong?

It is true, and it is for the reason I gave above. I can try to clarify again if needs be?

The other, more fundamental way of looking at it is like this:

Everyone and everything travels at the speed of light through space-time. If you're travelling at the speed of light through space, you have no velocity "left" to travel through time. Similarly, if you do not travel through space, you must travel at the speed of light through time, in order to meet your speed-of-light requirement.

(It is slightly more complicated than that, and to an extent you'll have to take my word for it, but it is the case)

**Enzo** · September 25, 2012, 04:15 AM

Units of experiential awareness in a sequence that flows seamlessly from one moment to the next and its also the thing that stops everything from happening all at once.

**Gaidin** · September 25, 2012, 06:27 AM

Also, the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom. Which, ironically, I think also accounts for the relativity mishaps depending on where that cesium atom is and what it's doing.

**Morkonan** · September 26, 2012, 10:12 PM

Originally Posted by Stildawn

... I didn't know that time was tangible?

Time is relative. The "Time" that you experience, right now, and that I experience, * "Right Now", is NOT the same. For one thing, differences between our two altitudes likely means that one of us is experiencing time at a faster rate than the other, due to our relative "depths" in the local gravity well. (Earth, in this example.)

* "Right Now" is also meaningless gibberish, since information can not be exchanged in any meaningful way faster than the speed of light. So, a "Right Now" taking place between two observers isn't really possible to speak to. But, the difference is small enough not to really worry about.

So basically I have come to the conclusion that I don't know what time means.

Ready for your answer? This is what time means - Something Happens. "Time" makes things happen, makes change possible, provides a format to render what otherwise would just "be" into something that "does." Without it, nothing would ever occur. Because of that, some insist that Time is evidence only of Entropy. Others say that it is just an Interpretation, limited by our capability to experience certain physical law. Some insist it is linear, only ever occurring in one direction, while others maintain that the Universe is destined to undergo a change where Time reverses polarity. There is even evidence to show that Time can be radically manipulated under certain circumstances, given extraordinary amounts of energy. Most would agree that Time is a real component of our existence, whether physically represented in 4D space, 3D space with a collection of laws that exhibit "Timelike" qualities or, whatever.

The point is that Time is real, can be variable due to certain circumstances and we are capable of observing differences in Time - Stuff happens.

**PointOfViewGun** · September 27, 2012, 09:44 AM

I don't think time can be explained in a simple way. It's one of those ideas that can only be explained with the use of that idea.

**I WUB PUGS** · October 01, 2012, 03:34 PM

A unit of measure man has applied to an event so he can plan things according to a set of numbers.

Time isn't any more real or than inches or meters are.

**Col. Tartleton** · October 01, 2012, 04:20 PM

Originally Posted by I WUB PUGS

A unit of measure man has applied to an event so he can plan things according to a set of numbers.

Time isn't any more real or than inches or meters are.

Perhaps it would be better to say Time isn't any more real than Distance.