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Time travelling

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If Hawking doesn't think it's possible that's good enough for me

Please tell me you're kidding - he used the "no visitors" argument.

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Here's one for you...

 

If you travelled back in time to yesterday how would the universe know where to put each particle of matter and energy??

The computer this simulation is running on would have to have random access memory. But there is no hard drive storing the log file for the universe.

So the only way to move through time is linearly, either forwards like we are or backwards.

 

Travelling forwards quicker or slower than we currently are (time dilation) isn't a problem because you're moving through each instant of time as is the rest of the universe but you're moving from one to the next quicker or slower than the rest of the universe.

Because all the particles are following their natural path from one instant to the next.

 

So to "rewind" time the entire universe is going to have to throw all those particles into reverse just for you.

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Please tell me you're kidding - he used the "no visitors" argument.

 

That reminded me of something else I was thinking about RE this thread..

I'm going to start talking about aliens visiting us from other worlds. :-(

I'm not going to say they do exist just theorise about what they might be..

 

The chance of any life that developed on another planet turning out to look almost human like is astronomical. The number of different ways for life evolving on alien worlds is unbelievable.

 

So let's forget about these "aliens" we keep getting reports of coming from other planets.

They look far too much like the human race after a few million years more evolution OR a few generations of genetic manipulation. ;)

 

So the most likely explanations are they could either be humans from our future, genetically enhanced to survive the trip or something like that.

Or just figments of peoples imaginations, back in the days when aliens were first "invented" they wouldn't have realised the chances of aliens having arms and legs with 5 digits on each, 2 eyes, 2 nostrils, a single mouth, 2 ears etc.. would be slim to none.

 

So they're either us from the future or figments of our imaginations from our past.

And until Hawking finds out whether they're actually real or not how can he say we've never been visited by people from the future??

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Maybe unconventional but necessary?

No!

 

It depends on where you look. I know Alan Guth's model of inflation (multiple universe theory) has 2D, that's where I got the idea that quantum mechanics was 2D.

 

Inflation does not have two time dimensions. Look at astro-ph/0404546 which is a review (by Guth) of inflation. There is most certainly only one time dimension - look at the signature of the metric after Eq.(1.4).

 

I also know M-Theory cosmology is; simply, because each brane is not on one standard time and therefore the branes themselves lie in a higher dimension of time (and space).

 

No it isn't. The branes are separated in space, not time. Oh, there may be one or two bizarre models out there which do have multiple time dimensions but they are the sort of theories which do not get good receptions at conferences....

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And until Hawking finds out whether they're actually real or not how can he say we've never been visited by people from the future??

Well quite.

 

Like they'd be walking around with big placards that said "we're from the future! please interrogate and dissect us, because disrupting the universe is FUN!"

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Well quite.

 

Like they'd be walking around with big placards that said "we're from the future! please interrogate and dissect us' date=' because disrupting the universe is FUN!"[/quote']

 

You're accepting the possibility that these "aliens" could be us from our future??

Does that mean you're accepting that they probably are us from our future too??

 

I hope you are cos that means we can start discussing why they've never made real contact with us. All they've done is the typical time traveller stuff we'd do on people if we went back in time ourselves.

 

We'd abduct people, look at how they're developing then after wiping their memories of the event, stick them back so it wouldn't affect our time when we came home.

We'd probably be interested in other species development too, we'd do experiments on cows to see how they were developing and how as being a food source they affected human evolution.

 

What if we stuck a huge sign up saying "We know who you are!!"??

 

Maybe we're looking at time travel the wrong way.

Instead of spending time and energy trying to figure out how to become time travellers we should spend be trying to figure out how to become people visited by time travellers.

Doesn't that make more sense?? It's easier to stick that sign up than create a time machine simply because we already know how to make signs. ;)

 

But what could we use to send a signal to these aliens (aka ourselves from our future) saying we know what/who they are??

Well if they're from our future and they'll know all our knowledge all we should need to do is send a message to the future.

What the Hell would happen if a huge number of people started accepting this theory?? Would our future selves would go back to that time and introduce themselves...

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Inflation does not have two time dimensions. Look at astro-ph/0404546 which is a review (by Guth) of inflation. There is most certainly only one time dimension - look at the signature of the metric after Eq.(1.4).
I read the abstract and it says nothing abotu only one dimension of time.
No it isn't. The branes are separated in space, not time. Oh, there may be one or two bizarre models out there which do have multiple time dimensions but they are the sort of theories which do not get good receptions at conferences....
If there’s only space, then wouldnt you agree that nothing would ever happen. Unless, of course, we conclude time really doesnt exist in first place...but for most theories, with out time: nothing happens.

 

And again, I'm not taking a position. You're taking the rather limited side that there is only 1 time dimension. This is pointless. You're not even responding to everything I say.

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I read the abstract and it says nothing abotu only one dimension of time.If there’s only space' date=' then wouldnt you agree that nothing would ever happen. Unless, of course, we conclude time really doesnt exist in first place...but for most theories, with out time: nothing happens.

[/quote']

 

Why would nothing happen with one time dimension? The Standard Model has only one time dimension and it is the best tested theory ever!

 

And again, I'm not taking a position. You're taking the rather limited side that there is only 1 time dimension.

 

No - I am happy to entertain new ideas. I was objecting to your statement that most theories have multiple time dimensions, or that multiple time dimensions was somehow natural.

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Why would nothing happen with one time dimension? The Standard Model has only one time dimension and it is the best tested theory ever!
I said with NO time, nothing happens.

 

“but for most theories, with out time: nothing happens.”

 

What you did is called a strawman, which is pointless because I don’t want to debate you.

No - I am happy to entertain new ideas. I was objecting to your statement that most theories have multiple time dimensions, or that multiple time dimensions was somehow natural.
I really meant most cosmologies, and I never tried to argue that multiple timeD’s were ‘natural.’

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I said with NO time, nothing happens.

 

Sorry - I misread your post. I agree that we need to have at least one dimension of time, so I think it was your statement which was the strawman - to suggest that there be no time dimension is jsut silly.

 

I really meant most cosmologies...

 

Fair enough, so justify the statement. I just posted a review on inflationary cosmology by Guth himself, who you cited as having invented cosmologies which require multiple time dimensions. He does not mention multiple time dimensions! If the alleged creator of the theories of multiple time dimensions does not deem them fit to mention in a review article, it does not seem justified to suggest that 'most cosmologies' include multiple time dimensions.

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Sorry - I misread your post. I agree that we need to have at least one dimension of time, so I think it was your statement which was the strawman - to suggest that there be no time dimension is jsut silly.
Do you mind explaining where my post misinterpreted you?

 

“to suggest that there be no time dimension is jsut silly”

 

It was a statement similar to that one that started this whole thing.

 

Don’t be so dogmatic, please. What if we could represent time as another spacial dimension? We have a quanta of time, namely the chronon, there is a model where time is treated like a particle.

Fair enough, so justify the statement. I just posted a review on inflationary cosmology by Guth himself, who you cited as having invented cosmologies which require multiple time dimensions. He does not mention multiple time dimensions! If the alleged creator of the theories of multiple time dimensions does not deem them fit to mention in a review article, it does not seem justified to suggest that 'most cosmologies' include multiple time dimensions.

Alan has at least two main theories that each have many theories of themselves. One is known as inflation, and the more commonly known one is multi-universe theory (bassed off inflation). I never saw him mention only one time dimension (it may have been to explain a concept, so don’t pull things out of context if you wish to challenge that statement). I said earlier that I remember reading the concept of a quantum mechanical model of 2 time dimensions in his book. That doesnt necessarily mean his basic model. There are other models that attempt to explain why the universe exists, several actually, that he explains throughout that last third of his book.

 

Beside, that is one theory (actually hypothesis but whatever).

 

M-Theory cosmology is a definite 2D(+). If we conclude that our brane lays in a higher brane, and not just another dimension, then we have 3D of time. But the least amount of time dimensions in this cosmology is 2.

 

I remember this one cosmology, I think some black hole cosmology where a black hole is a seed for a new universe (it is a singularity) has infinite ‘layers’ of time. Each universe could be explained as a quanta that interacts with other universes through the higher ‘mother’ universe or something which is seen as black hole interactions (black holes themselves are treated similar to atoms). Its been a while sense I read an article on it though.

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I tend to agree with this idea that time is not a dimention. It appears to me as just a method of measuring the pasage of a moment from the future to the past. Noting that our view of the universe is distorted by the fact that all we see is history. I understand a dimention as somthing like width, depth, and hight. Time is somthing diferent.

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Do you mind explaining where my post misinterpreted you?

 

You appear to suggest that I believe there is no time dimesnion at all.

 

Don’t be so dogmatic' date=' please. What if we could represent time as another spacial dimension?

[/quote']

 

The only thing which distinguishes a time dimension from a space dimension is the signature of the metric. If the signature is such that your 'time' dimension has the signature of a space dimension, then it is a space dimension!

 

We have a quanta of time, namely the chronon, there is a model where time is treated like a particle.Alan has at least two main theories that each have many theories of themselves. One is known as inflation, and the more commonly known one is multi-universe theory (bassed off inflation).

 

[snip]

 

M-Theory cosmology is a definite 2D(+). If we conclude that our brane lays in a higher brane, and not just another dimension, then we have 3D of time. But the least amount of time dimensions in this cosmology is 2.

 

I am sorry but I don't believe any of this. Could you please provide links to Guth's papers on his 'multiverse' theories where he has multiple dimensions, and links to papers describing M-theory with 2+ time dimensions. Because every M-theory paper I have ever read has 1 time dimension; the branes are separated in space, not time.

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I tend to agree with this idea that time is not a dimention. It appears to me as just a method of measuring the pasage of a moment from the future to the past. Noting that our view of the universe is distorted by the fact that all we see is history. I understand a dimention as somthing like width, depth, and hight. Time is somthing diferent.

 

I've got to agree with astromark but 1veedo and Severian left me behind ages and ages ago in another time dimention. ;)

 

The only extra dimensions of time I can grasp are 2 sorts.

#1 At the quantum level in string theory where strings can do crazy things like exist in two places at one time. So strings can move forwards (maybe backwards??) and sideways, which I don't think is a really accurate description because when they move to the other place in space as well as time they're moving sideways... Then again we can't see what's going on yet.

 

 

#2 Is the multiverse theory where there have been multiple big bangs forming seperate universes in the original nothingness that our universe hovers about in. If these seperate big bangs happened at different times each universe could have a different number of seconds since creation variable.

These aren't really extra dimensions of time because it's just the seperate universes that exist in other dimensions with time flowing like it does in our universe.

Those are the (mem)branes you two guys are talking about, right??

 

If there are any more theories for how there could be time could be different I think we'd all like to know about them... Those of us who don't know about them yet anyway. ;)

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grrr...there is no nothingness. for anything to hover in anything it would need space. space was created in the big bang.

 

brane theory is the closest i will get to accepting a multiverse type deal thingy.

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grrr...there is no nothingness. for anything to hover in anything it would need space. space was created in the big bang.

 

LOL

I know exactly what you mean but I struggle to describe the thing that didn't exist before the big bang.. What's the conventional terminology for it??

 

I had lots of fun once trying to explain the concept to a friend. He tried telling me there was this nothingness before the big bang which also surrounds our universe. I kept trying to explain to him that there was no nothingness there because in accordance with our perception of things - even nothing is something, it's like an empty place where things can exist but the "nothingness" I refer to there's nothing that could ever move into it.

 

The only way I could express it was by calling it a dimension before dimensions which never even existed... I think that blew his mind and he just accepted it to end the debate. ;)

 

brane theory is the closest i will get to accepting a multiverse type deal thingy.

 

Yup agreed!!!

I like the idea of black holes sucking matter in to make miniverses but I think that's all it is, an idea... I see black holes more as matter to energy convertors of some kind.

 

As for parrallel universes where every possibility is played out, I can't accept those either.

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You appear to suggest that I believe there is no time dimesnion at all.
:roll: lets recap.
I read the abstract and it says nothing abotu only one dimension of time.If there’s only space, then wouldnt you agree that nothing would ever happen. Unless, of course, we conclude time really doesnt exist in first place...but for most theories, with out time: nothing happens.
Why would nothing happen with one time dimension? The Standard Model has only one time dimension and it is the best tested theory ever!

I am sorry but I don't believe any of this. Could you please provide links to Guth's papers on his 'multiverse' theories where he has multiple dimensions' date=' and links to papers describing M-theory with 2+ time dimensions. Because every M-theory paper I have ever read has 1 time dimension; the branes are separated in space, not time.[/quote']Whatever dude, I don’t even want to tackle this. I can only say: Buy the inflationary universe.

 

Just listen to yourself.

 

Without time nothing happens. Branes collide in M-Theroy...well, I guess they don’t any more! Seriously, you need time to describe brane interactions. This means we need 2.

#2 Is the multiverse theory where there have been multiple big bangs forming seperate universes in the original nothingness that our universe hovers about in. If these seperate big bangs happened at different times each universe could have a different number of seconds since creation variable.

These aren't really extra dimensions of time because it's just the seperate universes that exist in other dimensions with time flowing like it does in our universe.

Those are the (mem)branes you two guys are talking about' date=' right??[/quote']Correct.

If there are any more theories for how there could be time could be different I think we'd all like to know about them... Those of us who don't know about them yet anyway.

If I remember correctly, in the self reproducing model, you have one time dimension that treats all the ‘pokcet universes’ as particles. Basically you have a False Vacuum that creates a +universe that can fluctuate into three universes with the uncertainty of the charge between the false vacuum..... So you get -universes and so on. However, these pocket universes will evolve on their own, and can switch charges. This, kindof like time travel, affects the “main” timeline so everything down the road will fluctuate, universes will go out of existence, or will switch charges... etc.

 

Lets explain this visually.

 

(V[acuum] s[mall] L[arge])

 

1. V s- V L+ Vs - V

2. V s- V s- V 0 V s+ V s+ V

1.1 V s+ V L- V s+ V

The new second ‘second’: V + V which can of course break into tow smaller negative and a large neutral pocket universe.

 

Just like particles.

 

PS: This is a universe from nothing model.

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Seriously, you need time to describe brane interactions. This means we need 2.

 

Why would you need 2 time dimensions to have colliding branes? One is enough. You can have 2 surfaces in a higher dimensional space collide with only one time dimension - it is just the higher dimensional analogue of dropping a piece of paper on a table. I don't need two time dimensions to do that - do you?

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Why would you need 2 time dimensions to have colliding branes? One is enough.
Yes, one is enough for coliding branes. But are you implying that these branes are static? They evolve on their own as well, and every once in a while have an outside force acting on them.

 

------

 

http://www.damtp.cam.ac.uk/user/gr/public/qg_qc.html

 

This explains two of the concepts I was talking about earlier.

 

1) Quantum cosmology has two dimensions of time.

2) Time can be described as a spacial dimension.

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I think I see where you are coming from now 1veedo.....

 

...although I still disagree. The confusion is arising because of the analytic continuation from a Minkowski metric to a Euclidean metric. The time dimension is converted into a 'space' dimension by analytic continuation into the complex plane. But this is just a mathematical trick in order to solve the mathematics - it isn't really being turned into a space dimension. They just do this to solve the maths and then continue back again to the usual 3+1 Minkowski metric.

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I thought what you actually had was 'real' time and 'imaginary' time. The way it sundsl like its constructed is one time dimension describing the evolution of 4 spacial dimensions, one of which is time.

 

ie T[x, y, z, imaginary time]

 

After reading it again it seems more like euclidean field theory replaces real time with the imaginary time axis it corresponds to. Rather than having 4 dimensions of space-time, in imaginary time it's 4Dspace.

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I did not want to get involved but, i'll tell you 2 simple things.

Time is the comparation of movements... then it was implemented mathematicaly, but time is movements comparation just that, then acording to relativity theories, if two things are in 2 diferent inertial fields, then you would see some sort of time bending.

then, thinking about time for 3D time, and stuff, is first, useless, and second stupid.

 

¿questions?

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time is not a 4 dimention by the way... i mean. is like a set of fruits... thinking that a are apples are x, pears are y, and pineapple are z, and we put rocks as t (for time)....

is stupid and nonsense.

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??

 

Can you explain your first post post again? I dont quite understand what you're talking about.

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