Time as a dimension

[Lord Hugh]

sorry, bit late to this thread, takes me a while to catch up...

Originally posted by Stig
So this means that if something is not moving at all in space, it is therefore travelling thorough time at the speed of light?

In the same way that light, since it travels at the speed of light, does not move with any velocity through time?

It was me that posted that response to windsor actually (though I'm flattered you'd mix us two up ) but anyway c is the speed of light in a vacuum, ie when it is not passing through any matter. It slows down in other mediums (this is why refraction occurs - classically anyway, the quantum explanation is probably different). Since all matter is moving (heat is the movement of electrons in a substance) & cannot be not moving (the temperature absolute zero can't be reached, not sure on the exact reasons for this) this seems to imply to me that time actually does only exist while matter exists, as windsor sorta said, since all electromagnetic radiation moving in a vacuum moves at the speed of light.

So I was wrong earlier. I think. Hmm.

 

[jcsd]

sorry, bit late to this thread, takes me a while to catch up...

Originally posted by Stig
This is kind of answered by what jcsd posted above:

So this means that if something is not moving at all in space, it is therefore travelling thorough time at the speed of light?

In the same way that light, since it travels at the speed of light, does not move with any velocity through time?

Sort of.

All rest frames in special relativity are equal, that is to say that anyone who is not undergoing accelartion can say that they are at rest, however light or more generally anything travelling at c does not have a rest frame (i.e. you can't talkabout things from the point of view of an object travelling at c).

Four-vectors aren't quite the same as the three-vectors of non-relativistic physics, but when if you consider only the componets in the spatial dimensions in a certain rest frame for a four-vector you get a normal three-vector in that rest frame.

It is a good analogy though and I think Brian Greene does actually use a very simlair analogy though in his book The Elegant Universe.

 

[windsor]

What IS Light?

Light doesn't MOVE; it beams for a duration of time.

It beams until it runs out of excited particles expressing light.

It can beam light in colors; and in intensities; in a straight laser line; and as a lit orb, from a central point.

A light can be seen as point, line, location and duration. It has all the characteristics for study that you need to challenge cause-and-effect. Thus, Light is identifiable and recognizable IN TIME, once it has established a pattern of behavior.

Darkness, on the other hand, has none of these qualities. Darkness is merely the receptacle into which Light emanates. Yet, receptacles are also essential; they are safe spaces that accept growth-in-time-and-iin-space.

The darkened womb in which we became human was just as vital as the light and breath and touch and motion of our mothers. It was safe.

Scientists describe physical reality in materialist terms. But for those of us who feel and sense the personality of God and the presence of angelic devotion over human lives, physical reality is merely the palate on which thoughts and feelings play.

It's our sand box to play in, while we're here learning the links between causes and effects. The Light bulb going on over our head is actually physically REAL when we get an idea. Voila! And when we exhausted, spent and down in the dumps, YES!, our physical aura takes on a "blue" cast to it. Our spirit LOOKS blue!

Oh, I can really get tangled up in all these connections, can't you?

--w

 

[fractionMan]

One of my old schoolo mates had a theory that light was in fact the absence of darkness. Ligt bulbs for example, absorb light he would say. Unlike windsor however, he was joking and wen t on to get a phd in chemistry.

 

[Lord Hugh]

What IS Light?

Originally posted by windsor
Oh, I can really get tangled up in all these connections, can't you?

Not quite as much as you.

A light can be seen as point, line, location and duration. It has all the characteristics for study that you need to challenge cause-and-effect.

What are you talking about?

 

[Sacri Liege]

What if everything is moving 'inward' at light speed, inward as a fourth spacial dimension. Imagine the web of time-space fabric emnating outwards from everything having mass. Then because light has no mass, casting a beam of light would be akin to dropping a lined anchor off a moving train.

Anyhow, this thread reminds me of another thread months ago, and I've got another question pertaining to that.

Ok, light speed is that fastest anything can travel, so if two ships travel in opposite directions both at 90% C they will be moving away from each other at 180% C but within their frame of reference will only be able to perceive a 90% movement rate.

So if they then circle around in a wide orbit and head for a collission course, what will happen?

If they both start at A and work their way towards B, either ship will get there but from their frame of reference the other ship will still be at X because if the other ship was at B it would have had to have been observed at faster than light speed travel. So where would the actual collision take place?

 

[windsor]

Where will they meet ?

Where is not the issue. The issue is getting both projectiles, "on the same page" with the same objective, to meet, so each can competently adjust course until that meeting occurs.

If they are not both focused on the meeting so the direction of travel appears to be motionless or in a straight line, they will simply miss each other and head off on a random path. Quite often, one must course-correct continually, as when a race driver is driving around an oval course.

If they don't keep their minds on the intention to meet, they'll lose orientation and never show up when they are expected to be there. It takes mental intention [intelligent design] to arrive at any destination.

So, who are your drivers, in this case, in your diagram?

Even drones must overcome obstacles, to meet their scheduled arrival.

 

[jcsd]

Originally posted by Sacri Liege
What if everything is moving 'inward' at light speed, inward as a fourth spacial dimension. Imagine the web of time-space fabric emnating outwards from everything having mass. Then because light has no mass, casting a beam of light would be akin to dropping a lined anchor off a moving train.

Anyhow, this thread reminds me of another thread months ago, and I've got another question pertaining to that.

Ok, light speed is that fastest anything can travel, so if two ships travel in opposite directions both at 90% C they will be moving away from each other at 180% C but within their frame of reference will only be able to perceive a 90% movement rate.

So if they then circle around in a wide orbit and head for a collission course, what will happen?

If they both start at A and work their way towards B, either ship will get there but from their frame of reference the other ship will still be at X because if the other ship was at B it would have had to have been observed at faster than light speed travel. So where would the actual collision take place?

You have to think relatively, in the rest frame of someone who is at rest to the circle both ships will start at moving away from each other both travelling at 90% the speed of light but in the rest frame of the ships (as you have set up an essientially spherical situation they will both see the mirror image of what the other ship sees assuming all things are equal) to begin with they will see each other moving in their respective rest frames at 180/181 the speed of light (or about 99.5% of the speed of light).

Unfortunely you've made your example quite complex as it involves both acceleration (which is not relative in special relativity) and the ships travelling along different axes (which means that we'd have to consider the differnt components of the velocity), but they will still both collide at point A in our staionery observers rest frame, or more genrally they will collide at event A in spacetime.

 

[Sacri Liege]

Yes, yes. Windsor, this is a hypothetical question, meaning we already assume they keep a straight course. I'm not worried about the navigational difficulties, the type of fuel they use, the type of pilots, or where they might go to the bathroom in the middle of space.

Originally posted by jcsd
You have to think relatively, in the rest frame of someone who is at rest to the circle both ships will start at moving away from each other both travelling at 90% the speed of light but in the rest frame of the ships (as you have set up an essientially spherical situation they will both see the mirror image of what the other ship sees assuming all things are equal) to begin with they will see each other moving in their respective rest frames at 180/181 the speed of light (or about 99.5% of the speed of light).

Unfortunely you've made your example quite complex as it involves both acceleration (which is not relative in special relativity) and the ships travelling along different axes (which means that we'd have to consider the differnt components of the velocity), but they will still both collide at point A in our staionery observers rest frame, or more genrally they will collide at event A in spacetime.

Alright, to simplify things could we assume there is no acceleration and the ships can reach 90% C instantaneously? And you mean event B, not event A right?

It makes sense that they would collide at event B, but at the same time it doesn't. Either ship will see a mirror image of each other, true. So assume they kept tracking instruments on their sister ship the whole flight. They could in no way perceive, from their frame of reference, the other ship to be accelerating at a rate that would bring them in contact with their own ship by the time they reached B. According to all possibility in either ships perspective, the other ship could only be at X when they reach B, if the other ship was any farther it would have been traveling towards them at faster than light speeds which is impossible within a single frame of reference.

So would the collision take place before the other (either) ship's 'projection' caught up to a point where it actually meets? I mean, with airplanes travelling faster than the speed of sound the sound wave lags behind them and takes a while to catch up. Could it be something similar for a light wave? Being that the two ships are indeed moving towards at faster than light speeds, could the two ships meet before the energenic perception of them catches up? And if so how would this fit with a third observer from a relatively stationary perspective?

Oh yes, and one more thing, objects supposedly enlongate when travelling at near light speeds, so could it be possible that the collision could take place at X through B through X?

 

[jcsd]

Yes I mean event B.

I already assumed thta both ships started a 0.9c in our refence frame, the acclertaion comes from the fcat that their paths are not staright (accleration is a vector quantity), therfore there is an accleration acting on the ships towards the centre of the circle.

The ships would appear to be elongated along there direction of motion (the direction of their velocity at any given time) in our rest frame.

Just remeber this in our rest frame we all that happens is that we see the two ships go round the circle from A to B and collide. In the rest frame of the ships (the difficult thing is that due to their acclerationthey are constntly changing rest frame), they won't see exactly the same thing as we do however they will still collide at event B.

 

[Iainmc]

Feel free to correct me jscd but looking at some your equations. For instance. A square root which is the indice of a power of a half. Against an indice of a power of two would cancel each other out.
(No Im using a mac and i dont want to download your graph program)

if anyone doesn't believe me enter 9 and get the square root of it its 3. Then enter 9 into your calculator and place the indice of a half or 1over 2 to this ..you get 3 as the result.

Also when describing spacetime one usually uses quarternians to describe the geometry. It very difficult anyhow it like two dimensionals beings trying to really understand what a box placed on their plane would look like it as they would only see a straight line and not really comprehend the height and any angulation of the height.
Personally, I think time is a vector which transmutes through three dimensions and say the gradual erosion of a recognised shape which happens with age, if it could be super imposed upon the orginal shape would give you the overall picture of what it looks like in 4 dimensions.
However, being only a 3 dimensional being just like the two dimension one, my/our problem would be trying to truly understand the vector shape before us. Just like the two dimension being would only really comprehend the straight line and length or width and wouldnt be able to differentiate between a square box place upon its plane/world or a cone with the same base.
THINK ABOUT IT

 

[merlin wood]

Time waits for no-one whereas space is everywhere and waits for everyone.

 

[jcsd]

Originally posted by Iainmc
Feel free to correct me jscd but looking at some your equations. For instance. A square root which is the indice of a power of a half. Against an indice of a power of two would cancel each other out.
(No Im using a mac and i dont want to download your graph program)

if anyone doesn't believe me enter 9 and get the square root of it its 3. Then enter 9 into your calculator and place the indice of a half or 1over 2 to this ..you get 3 as the result.

Also when describing spacetime one usually uses quarternians to describe the geometry. It very difficult anyhow it like two dimensionals beings trying to really understand what a box placed on their plane would look like it as they would only see a straight line and not really comprehend the height and any angulation of the height.
Personally, I think time is a vector which transmutes through three dimensions and say the gradual erosion of a recognised shape which happens with age, if it could be super imposed upon the orginal shape would give you the overall picture of what it looks like in 4 dimensions.
However, being only a 3 dimensional being just like the two dimension one, my/our problem would be trying to truly understand the vector shape before us. Just like the two dimension being would only really comprehend the straight line and length or width and wouldnt be able to differentiate between a square box place upon its plane/world or a cone with the same base.
THINK ABOUT IT

You have to be specific some of the equations do cancel to simpler forms, but where that happens I have included the simpler forms.

In have seen quarternions used to describe spacetime, but not very often! Quarternions are are genrally (by convention) not used as vector analysis is preferred and the even more generally tensor analysis (as vectors are tensors of rank 1).

 

[Iainmc]

Sorry there windsor but light is discret photon packets emitted as wavelets which are perpendicular to the electric vector of propagation or orgin.... or something like that cause Im tHICK like.

 

[Iainmc]

One more thing merlin wood. I have watched your posts and think that you really should take up physics again. I also know you had problems with not enough maths covered but Im sure the open university could help.
Im not being sarcastic but bear in mind that the majority of scientists today just go thru the motions of a degree learn things by rote and cannot definitely tell you what an electron is. (sorry but thats an actual fact)
My point is not enough dreamers enter science its full of boring stony faced parrots with overly mechanical brains and fuck all imagination.
After all, bear in mind, Einstein was supposedly thick as shit by his teachers and couldn't get into a proper Maths course so he did the equivalent of an old poly degree system in physics ....and ...he obviously was stupid eh!!!

God I really dispair sometimes at the utter blinkeredness of scientists. Bear in mind that mathematical models are not necessarily REAL world models and hence maths is logic yes but not necessarily the ultimate answer for the REAL world. Ponder before posting everyone.

 

[Sacri Liege]

Originally posted by jcsd
they won't see exactly the same thing as we do however they will still collide at event B.

O.K. please entertain me one more time. What if the ships travelled in a straight line towards a common point maintaining the same speeds. All i want to know is how they could collide with the other ship when the other ship can't have reached them in that time frame without breaking relativity, and/or what they would see upon reaching B.

 

[spiralx]

Originally posted by jcsd
In have seen quarternions used to describe spacetime, but not very often! Quarternions are are genrally (by convention) not used as vector analysis is preferred and the even more generally tensor analysis (as vectors are tensors of rank 1).

Quaternions are used a lot in graphics programming to represent coordinate systems.

 

[merlin wood]

Originally posted by Iainmc
God I really dispair sometimes at the utter blinkeredness of scientists. Bear in mind that mathematical models are not necessarily REAL world models and hence maths is logic yes but not necessarily the ultimate answer for the REAL world. Ponder before posting everyone.

Thanks Iainmc. I've just learnt on the internet from a guy with a physics doctorate and who's still working on string/M theory, that this mathematically complex theory, which is thought by many to be the best candidate for a theory of everything, is useless at predicting cosmological observations, and any development of this theory doesn't look like it could be any use as a predictive theory on the cosmological scale. See.
http://www.mth.kcl.ac.uk/staff/n_lambert.html