time and space

[jamey2k9]

space and time are always somhow linked but what links them and how are they linked

[NowThatWeKnow]

They are linked by man to make math easier.

[Klaynos]

They are linked in special relativity by the 4-vector (google it) And also in general relativity, but I'm not familiar enough on the equations to comment on that.

[north]

space and time are always somhow linked but what links them and how are they linked

 

both space and time are linked because we are after the understanding of the movement of things

 

yet at the sametime neither has any influence on the outcome of the movement of things

[Martin]

They are linked by man to make math easier.

 

That's a rather astute observation, NowThat.

I doubt it will satisfy Jamey, though.

 

Jamey, Klaynos had a good suggestion, basically to learn some special relativity. Hopefully some of the math connected with it which doesn't have to be dreadful.

SR has a beautiful way of combining time coordinates and space coordinates into one 4D fusion of space and time.

 

You can picture it by suppressing one space coordinate so you have a 2+1 picture of 2D space and 1D time in a sort 3D block.

Then there is a cone of so-called "time-like" directions which are legal ways that the time-axis could go for some possible observer.

 

Or you can reduce space down to one dimension and make spacetime diagrams on a 2D piece of paper.

Imagine you are a creature that measures time and space with the same unit------seconds of time, and light-seconds of distance.

So a flash of light, drawn on your 2D diagram, is just a 45 degree line. Motions slower than light will be restricted to a certain sector or pie-slice, and so on.

 

Does anyone know a really clear simple online introduction to SR?

Edited March 2, 2009 by Martin

[Mr Skeptic]

Space and time are linked by the speed of light.

[north]

Space and time are linked by the speed of light.

 

abstractly , mathematically

 

only

[Klaynos]

abstractly , mathematically

 

only

 

In physics the only way things can be linked is mathematically.

[Airbrush]

abstractly , mathematically

 

only

 

It would be more precise to say space and time are linked by the speed of light ABSOLUTELY, not just abstractly and mathematically.

[jamey2k9]

so the only thing connecting time and space is the speed of light how does that work

[Klaynos]

http://en.wikipedia.org/wiki/Four-vector

 

[Airbrush]

so the only thing connecting time and space is the speed of light how does that work

 

They used to just call space "space". After relativity they call space "space-time" to be more precise. Be careful using the word "only" unless you really mean only. We don't know what else connects time and space. For now, the speed of light does just fine.

[jamey2k9]

how can speed connect two things together does carry glue and stickey tape ?

[Klaynos]

how can speed connect two things together does carry glue and stickey tape ?

 

There is a mathematical relationship between them which involves speed....

[jamey2k9]

so speed acts as a sort of magnet between space and time

[Klaynos]

so speed acts as a sort of magnet between space and time

 

Not really.

 

You can't make classical analogies that work for relativity... Space and time are the same looked at from different speeds... Is probably as close as you can get, as things travel at a faster speed relative to you the dimensions appear to rotate into each other.

[Edtharan]

so speed acts as a sort of magnet between space and time

What is it that links the Horizontal direction to the Vertical direction?

 

Both are dimensions.

 

Time is also a dimension, however, we can not arbitrarily choose to change out motion in that dimension. Also, we can not directly perceive along the Time dimension because the stuff that makes up the universe we see, also can not move freely through the time dimension.

 

Now, you can state a relationship between the change in position along one dimension (say horizontal) and the distance moved in the other dimension (say vertical). So we could state that for every 10 metres in the Horizontal dimension there is a change in distance of 1 metre in the vertical dimension.

 

this give s 10 metre horizontal /1 metre vertical

 

Now, what if this was something like this:

 

10 metres horizontal / 300,000,000 metres vertical.

 

What if this was representing the distance you were falling in space. Say you have a malfunctioning space ship where the main thrusters have failed and you only have lateral thrusters that are working. You could move 10 metres sideways for every 300,000,000 metres you fall towards the planet.

 

Why the big numbers? Well 300,000,000 metres per second is the speed of light.

 

That is light travels 300,000,000 metres for every second that passes.

 

Or you could look at it this way:

 

Light travels 1 second for every 300,000,000 metres it travels.

 

So we can state out speed in terms of the distance that light travels. We would be able to move 10 metres for every 300,000,000 metres that light travelled.

 

Time is just a dimension, albeit one in which we can not control our motions.

[jamey2k9]

it sounds to me more like time is linked to speed is it possible time is merely a speed

[Royston]

it sounds to me more like time is linked to speed is it possible time is merely a speed

 

They're both variables that depend on each other relativistically, but I'd use the term velocity (which is a vector, not a scalar, like speed). They are not the same thing (i.e speed and time).

[jamey2k9]

is it possible that time doesent even exsist

[Royston]

is it possible that time doesent even exsist

 

Is it possible that speed doesn't exist ?

 

What conclusions have you come to, thinking if time doesn't exist ?

 

I'd suggest you wrap your head round vectors, they're not hard. You start with a simple diagram, an arrow pointing up, and one perpendicular to that arrow. You label them, then you can apply models around this ideal situation.

 

What's the point in asking big questions, if you don't have the basics to begin answering those questions ? I realize that can sound incredibly rude, but your just throwing the question 'out there', that's not too hard to do.

[jamey2k9]

okay

and i said is it possible time doesent exsist what I meant was evryone treats time like its there that they could just grab that it actullly has exsistence isent time just a measurment

[Royston]

okay

and i said is it possible time doesent exsist what I meant was evryone treats time like its there that they could just grab that it actullly has exsistence isent time just a measurment

 

It's an independent variable in Newtonian mechanics, a dependant one in relativistic physics, that has just the same significance as speed...i.e you can't have one without the other (with the latter).

[jamey2k9]

would it be possible to break down time

[Royston]

would it be possible to break down time

 

There are extreme physical conditions (e.g a black hole) where such things do break down....but like I said, it would be worth your time, wrapping your head around the basics, then you'll start appreciating what you're asking.