FAO: Theory of relativity buffs

[Dj_Jestar]

Hi

I've recently had a pub chat with some mates about the theory of relativity, and two/three topics arose which were of particular interest to me.

1. "What happens on the other side of The Speed of Light?" elaboration:
In order to have the ability to pass the speed of light, an object must have negative mass. (nb: is this correct? If not, ignore the following) Which then sparked, what else must the object have? Negative velocity? Negative Time? Is there anything to support this (any/all 3)?

2. As the French would say: Le Big Bang. Universe started as some single point (singularity) that exploded. The Universe as we know it, is expanding. Will it eventually collapse, back into it's original singularity state? What will happen when it transfers from expanding to collapsing? Will time stop, then turn around and go backwards? Is this possibly what has been happening repeatedly since the beginning of everything - Continuous expansion, collapse, expansion, collapse, rinse repeat, etc.? (A friend dubbed this the "Slinky Effect")

3. and finally the obligatory.. if the Slinky Effect is true, what was "the beginning" and what will be "the end." of the Slinky Effect?

Pub + alcohol fueled discussions ftmfw.

 

[Darg]

Try to use your brain less while drinking. It can produce odd results.

 

[Droolinggimp]

I have no idea.

But saying that. If we was to travel faster then Light then surely we could be at any point in time or the universe we choose, or would we be infront of time and thus traveling in time? There fore we would not have any destination to arrive in as it wouldnt of been "made" yet. Probably..

I am trying to be serious btw. I might of got some facts and figures mixed up but I hope you get my point.

 

[D.P.]

Hi

I've recently had a pub chat with some mates about the theory of relativity, and two/three topics arose which were of particular interest to me.

1. "What happens on the other side of The Speed of Light?" elaboration:
In order to have the ability to pass the speed of light, an object must have negative mass. (nb: is this correct? If not, ignore the following) Which then sparked, what else must the object have? Negative velocity? Negative Time? Is there anything to support this (any/all 3)?

2. As the French would say: Le Big Bang. Universe started as some single point (singularity) that exploded. The Universe as we know it, is expanding. Will it eventually collapse, back into it's original singularity state? What will happen when it transfers from expanding to collapsing? Will time stop, then turn around and go backwards? Is this possibly what has been happening repeatedly since the beginning of everything - Continuous expansion, collapse, expansion, collapse, rinse repeat, etc.? (A friend dubbed this the "Slinky Effect")

3. and finally the obligatory.. if the Slinky Effect is true, what was "the beginning" and what will be "the end." of the Slinky Effect?

Pub + alcohol fueled discussions ftmfw.

1), pointless as you can not go FTL.

2) Currently, the universe is expanding at an increasing rate, which is somewhat perplexing as gravity should act upon all bodies slowing them down and eventually reversing the direction. But this isn't happening, due to some hidden energy effects. OS the universe will foreseeable always expand until it is just one big dark cold emptiness.

3) don't know

 

[Arcade Fire]

1. "What happens on the other side of The Speed of Light?" elaboration:
In order to have the ability to pass the speed of light, an object must have negative mass. (nb: is this correct? If not, ignore the following) ...

It's not correct (nothing can go faster than the speed of light according to relativity) so I'll do as you ask!

2. As the French would say: Le Big Bang. Universe started as some single point (singularity) that exploded. The Universe as we know it, is expanding. Will it eventually collapse, back into it's original singularity state? What will happen when it transfers from expanding to collapsing? Will time stop, then turn around and go backwards? Is this possibly what has been happening repeatedly since the beginning of everything - Continuous expansion, collapse, expansion, collapse, rinse repeat, etc.? (A friend dubbed this the "Slinky Effect")

Most accurate answer: no one knows. The equations of general relativity give utter nonsense as we approach singularities, so they don't make any sensible predictions about the big bang except that there probably was one. Many people are now working on quantum theories of gravity (including string theory) which might provide answers to some of the questions that you ask.

 

[Azagoth]

Another one to ponder is, if you're travelling at c in a craft of some description, what happens if you turn the headlights on?

 

[Efour]

Another one to ponder is, if you're travelling at c in a craft of some description, what happens if you turn the headlights on?

the emit a beam of light like normal its all relative don't ya know.

 

[Scuzi]

Another one to ponder is, if you're travelling at c in a craft of some description, what happens if you turn the headlights on?

The light wil emit as normal at the speed of light, relative to the craft?

 

[Blinkz]

Another one to ponder is, if you're travelling at c in a craft of some description, what happens if you turn the headlights on?

You'll travel back in time and have to fight biff in order to get the sports almanac before travelling back to the future to save the doc from being shot by terrorists so that you can go back to fight biff and.....oh no I've gone cross-eyed

 

[Samione]

I read a paper on travelling huge distances in space , it talked about manipulating space time around the object so, the object didn't itself travel but everything else around it moved, therefore not violating the theory of relativity, it involved a whole other bunch of stuff like negative energy and more, to the point that if I tried to write it down, it'd be even more of a mess than the rest of this post.

P.S I have no idea what i'm talking about i'm just trying to regurgitate some of what I read!

 

[panthro]

You're never going to get a definitive answer to 2 and 3!! This topic could go on forever......and Im too lazy to type atm! but, when an object is travelling at the speed of light the mass will be converted into energy, therefore having zero mass, to answer part of point 1.

 

[Dj_Jestar]

D.P./Arcade Fire/panthro - yes, that's my understanding, too - but Tachyon's tend to throw a spanner in the works: http://en.wikipedia.org/wiki/Tachyon

I like discussions that have no definitive end.

 

[Darg]

2) Currently, the universe is expanding at an increasing rate, which is somewhat perplexing as gravity should act upon all bodies slowing them down and eventually reversing the direction. But this isn't happening, due to some hidden energy effects. OS the universe will foreseeable always expand until it is just one big dark cold emptiness.

That's unless Steorn manages to harness this unknown power and make the universe collapse on itself!

 

[frying_pan_cat]

Another one to ponder is, if you're travelling at c in a craft of some description, what happens if you turn the headlights on?

It is impossible for an object with mass to reach the speed of light (relative to another object) so this will never occur. Anyway its all relative, so if you are going "at the speed of light" relative to another object whats to say they are not travelling at the speed of light and you're stationary?

 

[Arcade Fire]

D.P./Arcade Fire/panthro - yes, that's my understanding, too - but Tachyon's tend to throw a spanner in the works: http://en.wikipedia.org/wiki/Tachyon

Most physicists believe that tachyons don't exist, and I side with them. They're predicted by some theories, but are usually taken to be a sign that the theory is borked (not a technical term). We've certainly never observed one. But yes, it is an intriguing idea!

 

[Phalanx]

what I get confused with is Einstein's equation.

you can rearrange the equation to give you what C =

c² = (e/m)

(3x10^8)² = (e/m)

i mean, does this mean that the reason you need infinite mass to go at the speed of light due to the most energy you can get is (3x10^8)² joules or what?

 

[hendrix]

Another one to ponder is, if you're travelling at c in a craft of some description, what happens if you turn the headlights on?

The light from the craft still travels at the speed of light relative to the craft. There's a formula used (Lorentz transform i believe) that proves this, but 1) I can't find it 2) There's no way in hell i'm going to work through it during the summer off from physics degree

As far as the OP goes, negative mass/time seems absurd to me, 2) Universe is to big for my wee head, 3) guess there would be no way of knowing really.

 

[Darg]

what I get confused with is Einstein's equation.

you can rearrange the equation to give you what C =

c² = (e/m)

(3x10^8)² = (e/m)

i mean, does this mean that the reason you need infinite mass to go at the speed of light due to the most energy you can get is (3x10^8)² joules or what?

c is the speed of light.

EDIT: Sorry, on re-reading your post you knew already

 

[Coran]

Noones given a decent answer to part 2 so here's me having a go:

There's 3 possibilities.
1) The universe keeps expanding forever.
2) The universe expands but slows down and eventually stops meaning its size becomes constant.
3) The universe expands, slows down, comes to rest, then starts decreasing in size until eventually it collapses in on itself once again.

The result depends on the total mass of the universe which is something we can't really measure. There is a critical mass.
If the total mass is below this critical mass, option 1) happens.
If equal to, option 2) happens.
If above, option 3) happens.

If option 3 is true then indeed we would experience the 'slinky' effect. There would be no foreseeable beginning or end and no information could be passed between two successive slinky expansions.

[minor edit] Time would still keep going forwards, not backwards. You might be able to argue that time is reset each time but that doesn't mean we'll live exactly the same way each time. It would be completely different, a bit like trying to replicate an explosion with everything blowing up in exactly the same way. [/minor edit]

I hope I'm not sprouting complete rubbish. I didn't look that up but I have recollections and it seems to make sense.

 

[Manlove is my forte]

Hi

I've recently had a pub chat with some mates about the theory of relativity, and two/three topics arose which were of particular interest to me.

1. "What happens on the other side of The Speed of Light?" elaboration:
In order to have the ability to pass the speed of light, an object must have negative mass. (nb: is this correct? If not, ignore the following) Which then sparked, what else must the object have? Negative velocity? Negative Time? Is there anything to support this (any/all 3)?

2. As the French would say: Le Big Bang. Universe started as some single point (singularity) that exploded. The Universe as we know it, is expanding. Will it eventually collapse, back into it's original singularity state? What will happen when it transfers from expanding to collapsing? Will time stop, then turn around and go backwards? Is this possibly what has been happening repeatedly since the beginning of everything - Continuous expansion, collapse, expansion, collapse, rinse repeat, etc.? (A friend dubbed this the "Slinky Effect")

3. and finally the obligatory.. if the Slinky Effect is true, what was "the beginning" and what will be "the end." of the Slinky Effect?

Pub + alcohol fueled discussions ftmfw.

1) IIRC you will have infinite mass and be traveling forward in space but backward in time
2) You travel to work every day and go home every night. Does time ever travel backwards during this journey?
3) Its a cycle, kind of like the chicken and egg question. Which came first the big bang, the big collapse? where did the matter come from in the first place?