relationship between space and time

[Tren Bull]

does anyone else find it absolutely amazing that space and time are connected?

i mean the effects of this aren't seen until you start moving close to the speed of light but it still exists. even when were curling 60 pound dumbells on an incline bench, that dumbell is bending space and time.

weird huh?

[mick-g]

Without it there is no energy, lol! Sorry i was just remembering the Enstein theory. If we could travel the speed of light, i believe time slows down, doesn't it not? Im just kinda remembering old science classes. They took a person and if they traveled the speed of light and came back to Earth, everything would be like twice as old, yet you would still be the same age, or not much older than the day you left, so in retrospect, if you could travel at the speed of light continually and you could control at which time you came back to the same place, you could actually go into the future, but of course you wouldn't be part of it. The tricky part would be trying to go backward in time to get back to the way things were b4 you left.

[Tren Bull]

maybe its not clear what i am saying. well heres an example of relativistic effects

lets say were chillin on earth, ramming a needle into our leg, and a pole which is 500 billion miles long goes past us very close to the speed of light.

in our reference frame, the pole would be very short. if its going fast enough it could even be 2 inches long. thats NOT an optical illusion either, according to us, its 2 inches long, but to a person sitting on the pole moving past us, its 500 billion miles long.

[powerliftmike]

Time frames would be realitive. Too you time would not slow down. Too your friend outside the fictious space craft traveling the speed of light time would stop (or if near the speed of light, slow down).

[powerliftmike]

Of course only things without mass can go the speed of light. For a massed object, it would require an infinite amount of energy to go the speed of light. photons have no mass tho, so its the only thing that can go that fast. Mass can be converted to energy, but energy cannot be converted to mass.

[Tren Bull]

Without it there is no energy, lol! Sorry i was just remembering the Enstein theory. If we could travel the speed of light, i believe time slows down, doesn't it not? Im just kinda remembering old science classes. They took a person and if they traveled the speed of light and came back to Earth, everything would be like twice as old, yet you would still be the same age, or not much older than the day you left, so in retrospect, if you could travel at the speed of light continually and you could control at which time you came back to the same place, you could actually go into the future, but of course you wouldn't be part of it. The tricky part would be trying to go backward in time to get back to the way things were b4 you left.

ahh yes, the twin paradox. well technically, the person on the spaceship headed away from earth will see the people on earth aging faster than him, but thats only moving in one direction. but coming back the other direction, the people on earth will actually be aging slower than the guy on the spaceship.

also, the person on the spaceship will see (well technically we say observe) that all the things around him ie, the rest of the universe which is standing still relative to earth are compressed.

basically, what the people on earth call space gets turned into time for the person on the spaceship (which is moving away from earth close to the speed of light). this is the relationship between space and time that i was referring to

[Tren Bull]

Of course only things without mass can go the speed of light. For a massed object, it would require an infinite amount of energy to go the speed of light. photons have no mass tho, so its the only thing that can go that fast. Mass can be converted to energy, but energy cannot be converted to mass.

according to the lorentz transformation equations it is true that anything with mass cannot go the speed of light, but who knows if those equations hold true if you go fast enough?

i mean, light is said to have no mass. but have you ever heard of solar sails? its a method that spacehips use to move thorugh space. basically they have light from the sun hit the "sail" which is actually a large reflective surface. and it causes the sail and the spaceship to move in the opposite direction. this can be explained by conservation of momentum

[Tren Bull]

another thing that makes me believe that light has mass is that if it gets close enough to a black hole, it will be sucked in. this is due to the insanely strong gravitational force exerted by the black hole on the light photon... or wave... however you want to describe it

[tiger909]

did you guys know that space travel at light speed is impossible because even an ant to go at that speed would require infinite energy

[Tren Bull]

did you guys know that space travel at light speed is impossible because even an ant to go at that speed would require infinite energy

even if we could travel at the speed of light, i sure as hell wouldn't want to go on some long space trip... by the time we got wherever we were going, then came back so much time would have passed on earth that its not likely humans would even exist anymore

[AnabolicAndre]

I remember reading somewhere that if you were to go in to a continuous flight in space at near the speed of light time would be the same in space but however when you returned to earth time elapse would have been slower so its kind of like traveling in to the future. I think it wa measureed in nano-seconds but ultimatly still travelling through a time paradox into the future. So relativly speaking time travel is feasible.

reminds me of that crazy steven king book where an airplane flies into a time portal and only the people who were asleep survived through the portal, then when they returned to earth time was still until time caught up with them. I forget the name of the book, I read it like soph year of HS.

[cfiler]

I'm thinking back to highschool physics.

If you go faster than the speed of light, don't you go back in time?

[stunner5000pt]

according to the lorentz transformation equations it is true that anything with mass cannot go the speed of light, but who knows if those equations hold true if you go fast enough?

i mean, light is said to have no mass. but have you ever heard of solar sails? its a method that spacehips use to move thorugh space. basically they have light from the sun hit the "sail" which is actually a large reflective surface. and it causes the sail and the spaceship to move in the opposite direction. this can be explained by conservation of momentum

light has energy thus momentum... if that's what you mean

E = hc/L
p = h/ L

where h = planck's constnat
c = speed of light
p = momentum
E = energy
L = wavelength
theres many things (i think) that have energy but have no mass... look at neutrinos.. they carry energy with them...

also why you gotta ask questions to whom answers cant be found yet!

before we even try to imagine tackling a question liek this.. let's learn a lot of GR, strings, branes, QM etc etc... all grad school material

[stunner5000pt]

there are hypothetical particles called tachyons which cna travel faster than light... read up on them

the only way they ahve thought of goin faster than light is by creating 'warp drive' ... yup straight out of star trek haha... so we dont really violate any GR and SR physics we create a distortion in spacetime so that we dont violate any principles.

largely theoretical suchtheories are just myth and fantasy for now

[Tren Bull]

I'm thinking back to highschool physics.

If you go faster than the speed of light, don't you go back in time?

i dont know. i think that length contraction would be more of a concern. cause if you were to go the speed of light (or faster) then the universe would be so compressed, that youd theoretically travel an infinite distance in less than a second... like as soon as you are going the speed of light, you reach the end of the universe... and then what?

thats one thing that always messed with my head

[AnabolicAndre]

The universe has an end???

[stunner5000pt]

I'm thinking back to highschool physics.

If you go faster than the speed of light, don't you go back in time?

the set of equations we know about would not apply anymore

causality is violted (a causes b causes c, doesnt exist anymore)

other stuff too

[stunner5000pt]

The universe has an end???

can't say..

but chaances are that it is finite

[IronFreakX]

Damn Johan, still havent replied here ???

[Tren Bull]

light has energy thus momentum... if that's what you mean

E = hc/L
p = h/ L

where h = planck's constnat
c = speed of light
p = momentum
E = energy
L = wavelength
theres many things (i think) that have energy but have no mass... look at neutrinos.. they carry energy with them...

also why you gotta ask questions to whom answers cant be found yet!

before we even try to imagine tackling a question liek this.. let's learn a lot of GR, strings, branes, QM etc etc... all grad school material

yea but light also has to have some mass. how else can you explain how light gets sucked into black holes? if it were totally massless, then there would be no gravitational force on it... which is not the case

[T3/T4 GSR]

No way would you reach the end of the universe as soon as you went the speed of light. Look at how many light years a lot of stars are away. The light you see at this moment took years at the speed of light to get here.

[Tren Bull]

The universe has an end???

i dont think wel ever know the answer to that question

[stunner5000pt]

can't say..

but chaances are that it is finite

woulds ya taht because the big bang occurred n years ago and the speed of light is 3 x 10 ^8 m/s the universe has been expanding a finite amount of time at a finite speed thus it is finite

[Tren Bull]

No way would you reach the end of the universe as soon as you went the speed of light. Look at how many light years a lot of stars are away. The light you see at this moment took years at the speed of light to get here.

you're not thinking relativistically

[Tren Bull]

woulds ya taht because the big bang occurred n years ago and the speed of light is 3 x 10 ^8 m/s the universe has been expanding a finite amount of time at a finite speed thus it is finite

its strange to think about the big bang. but i believe thats what happened.

stars colapse and eventually explode all the time... im pretty sure that when that happens they call it a supernova

[T3/T4 GSR]

Explain what you mean here. Are you saying just the speed in itself would cause the universe to compress thus traveling faster than you are?

[AnabolicAndre]

I want a supernova those things sound hella dope.

But seriously this is such an intersting topic, I am definitly am way to uneducated to involve myself in in-depth conversation. But now i am intrigued and I def. will be researching it.

[stunner5000pt]

yea but light also has to have some mass. how else can you explain how light gets sucked into black holes? if it were totally massless, then there would be no gravitational force on it... which is not the case

this is a topic of GR... not something i can answer properly...

you ahve definitely seen those diagrams where it appears a mass is on a rubber sheet and the mass 'bends' the sheet... well mass creates a spacetime curvature. As a result anything traveling along a straight path (lgiht usually does this) as it approaches the mass will bend since the shortest path between two points on a curved surface is not a straight line but a curve. This a source of gravitational lensing. When light approcahes dead onto the mass it has to 'impact' the mass right? with black holes therer is a singularity that the light has to reach thus it gets 'sucked' into the black hole

[Tren Bull]

there are hypothetical particles called tachyons which cna travel faster than light... read up on them

the only way they ahve thought of goin faster than light is by creating 'warp drive' ... yup straight out of star trek haha... so we dont really violate any GR and SR physics we create a distortion in spacetime so that we dont violate any principles.

largely theoretical suchtheories are just myth and fantasy for now

i really doubt its possible to make a particle travel faster than the speed of light. i mean, no matter how fast you are moving, the speed of light is constant...

i know that sounds very abstract, so il put it this way. if one guy is on a spaceship going near the speed of light, and another guy is chillin on earth, and they both observe and measure the speed of light which is leaving a flashlight in the space ship thats already moving close to the speed of light, both the guy on the ship and the guy on earth will observe the light moving away from them at the same exact speed

[Tren Bull]

this is a topic of GR... not something i can answer properly...

you ahve definitely seen those diagrams where it appears a mass is on a rubber sheet and the mass 'bends' the sheet... well mass creates a spacetime curvature. As a result anything traveling along a straight path (lgiht usually does this) as it approaches the mass will bend since the shortest path between two points on a curved surface is not a straight line but a curve. This a source of gravitational lensing. When light approcahes dead onto the mass it has to 'impact' the mass right? with black holes therer is a singularity that the light has to reach thus it gets 'sucked' into the black hole

relativity has nothing to do with it. its putting a very small mass into a VERY strong gravitational field...

newtons 4th law of gravitation describes whats going on when light goes anywhere near a black hole... or any other mass for that matter. but a black hole is the only thing massive enough to create a strong enough gravitational field to suck the light in

[stunner5000pt]

its strange to think about the big bang. but i believe thats what happened.

stars colapse and eventually explode all the time... im pretty sure that when that happens they call it a supernova

there are problems with the big bang model which dont explain how stars were formed... this is what i was told ... i ahvent taken many astronomy courses.

if the big bang did indeed occur then the universe would have expanded uniformly in all directions. But why uniformly? i dont know. Let's say it did for now.

Now stars have to have localized concentrations of hydrogen and helium to fall into themselves due to gravitational force of their mass and ignite forming a star when the outward (by the energy generated by ignition of H and He) and gravitational pressures balance out.

But if the universe was expanding unifromly ... then how did localized concentrations of H and He come about? I'd liket osee explanations on this... if you can find theories i'd liek to know them.

[Polska]

i love stuff like this. quantum physics intrigues me. you should see the "what the bleep do we know" movies if you haven't already

[Tren Bull]

I want a supernova those things sound hella dope.

But seriously this is such an intersting topic, I am definitly am way to uneducated to involve myself in in-depth conversation. But now i am intrigued and I def. will be researching it.

haha yea supernovas are tight. i swear, God must be destructive.

haha, i can just imagine him sitting on his throne, pointing his finger at a star saying "God want BIG boom"



btw relativity is str8 weird. i love thinking about it cause it blows my mind

[stunner5000pt]

relativity has nothing to do with it. its putting a very small mass into a VERY strong gravitational field...

newtons 4th law of gravitation describes whats going on when light goes anywhere near a black hole... or any other mass for that matter. but a black hole is the only thing massive enough to create a strong enough gravitational field to suck the light in

newton's laws dont say anything light (because it has no mass) and gravity

and there isn o Newton's 4th law

there are only 3 Newtonian laws and they have nothing to do with gravitation directly - they do not state the relationship between mass, force and distance.

[stunner5000pt]

Only GR predicts the bending of light under gravitational fields

From Wikipedia
Bending of light

This bending also occurs in any accelerated frame of reference. However, the details of the bending and therefore the gravitational lensing effects are governed by spacetime curvature.

* The magnitude of this effect is twice the Newtonian prediction. It was confirmed by astronomical observations during eclipses of the Sun and observations of pulsars passing behind the Sun.
* Gravitational lensing: One distant object in front of or close to being in front of another much more distant object can change how the more distant object is seen. These effects include
o Multiple views of the same object: Observations of quasars whose light passes close to an intervening galaxy.
o Brightening of a star due to the focusing effects of a planet or another star passing in front of it: Such "microlensing" events are now regularly observed.
o Einstein rings and arcs: One object directly behind another can make the more distant object's light appear as a ring. When almost directly behind, the result is an arc. Observed for distant galaxies.

[Tren Bull]

there are problems with the big bang model which dont explain how stars were formed... this is what i was told ... i ahvent taken many astronomy courses.

if the big bang did indeed occur then the universe would have expanded uniformly in all directions. But why uniformly? i dont know. Let's say it did for now.

Now stars have to have localized concentrations of hydrogen and helium to fall into themselves due to gravitational force of their mass and ignite forming a star when the outward (by the energy generated by ignition of H and He) and gravitational pressures balance out.

But if the universe was expanding unifromly ... then how did localized concentrations of H and He come about? I'd liket osee explanations on this... if you can find theories i'd liek to know them.

i dont know man, i wasn't there, so i shouldn't claim that i know what and why it happened

[AnabolicAndre]

But if the universe was expanding unifromly ... then how did localized concentrations of H and He come about? I'd liket osee explanations on this... if you can find theories i'd liek to know them.

Well hasn't there always been free form gases, through out the universe. Polarit of He and H atoms would cause them to conform and bunch, and eventually instabilty would cause a reaction, that if large enough mass compounded became unstable you would get a similar racetion to the "big bang" Not to that extent but a smaller yet similar reaction.

[AnabolicAndre]

I wonder what on the other side of a black hole. There has got to be a lot of shit in there seeing as how it pulls everything in its path in.

BLACK HOLES are the only thing powerful enough to draw in light right?

[stunner5000pt]

Well hasn't there always been free form gases, through out the universe. Polarit of He and H atoms would cause them to conform and bunch, and eventually instabilty would cause a reaction, that if large enough mass compounded became unstable you would get a similar racetion to the "big bang" Not to that extent but a smaller yet similar reaction.

The problem is that i doubt London Forces (a type of Van der Waals force) would cuase this to occu because as soon as the temporary diploes attract they would be replled just as fast... no locailized bunching wiuld occur as a result.

[Tren Bull]

Explain what you mean here. Are you saying just the speed in itself would cause the universe to compress thus traveling faster than you are?

not exactly. im not sure what causes length contraction and time dilation... but once you start moving near the speed of light relativistic effects become more and more noticable. weve even measured time dilation. relativistic effects always occur no matter what speed you're moving, but at slow speeds, its effects are so small that you can neglect them for practical applications... well for engineering projects here on earth.