WormHoles

BoneCollector

Any way.... moving right along..
Scientist have said that its much easier to travel forward in time than back.

However.. as stated in 4th dimention reopend

they have stated that using a worm hole would be the best approach. The term Worm hole does not neccaseraly mean what you seen in startrek it is a term applied to a method of creating a doorway which envokes gravitational forces to allow time travel.
obviously this i beyond current technology but this is what is being discussed.

PLEASE GIVE CONSTRUCTIVE INPUT OR IGNORE THIS POST

DeadBankClerk

afaik
space is curved and a worm-hole is a passage through 'sub space' ie: space is curved like a hair-pin bend and a worm hole is like cutting the corner. you travel from one place to another, and arrive before you are able, because nothing can travel faster than light.

(based on lots of discovery channel, a brief history of tme and some issac asminov book my mate leant me

DeVore

That is pure theory though. Noone has ever shown that while space-time may be curved near large mass objects, it can be curved MORE to facilitate some form of *hop* between locations.

Frankly, speaking as someone with a degree in Pure Math, I find the area somewhat more fanciful. I dont object to the discussion of the topic in Science but I dont believe that what was a good analogy by Einstein (of the rubber mat with a lead ball on it) should be taken as literally as it has been in some sci-fi authors books.

There are far too many paradoxes and anomalies (much loved by Star Trek writers) to be considered. Yes, at the point of a singualrity we know that conventional Einsteinian physics and even perhaps quantum mechanics, (though I cant say that for certain) simply dont work. Newtonian mechanics went out the window long before that point

Perhaps a unified theory will elegantly explain the seemingly ugly anomolies of singualities similarly to how quantum mechanics explained the problems at the extremely-small-scale. However I dont think anyone will ever show that space-time is both curved AND flexible .


That is the single most brainiac post I've put on Boards in a long time, and now I think I need to go to lie down...


DeVore.

DeVore

btw, when I said I dont mind this being discussed on the Science board I mean in scientific terms. I've just read far too much fluff on the other threads which is non-scientific based. I am happy with the idea that (as Einstein himself said, in paraphrase)
No idea which does not at first seem ludicrous, can have value!
but we need to stay rooted in science.
Science is approached in three stages:
Observe (or hypothsize, for non-experimental sciences)
Theorise
Prove.
If you are in stage one, listen to the input of people who have knowledge of the other two stages




Still, I think there is a wealth of info on this topic (space-warping)out there which need not be addressed in this forum.

There are some very interesting experiments in the Australian desert into FTL particle acceleration, the results of which are hotly contested.

Someone asked about proof of clocks beating at their own pace. It has been shown that a clock which is accerlated to near speed of light will show a different time from a clock left on Earth. It is well accepted at this point that time is relative to the location of the observer.

Interestingly, if you were also on that near-light-speed craft with the clock, you would experience time normally, and arrive back to earth with MORE time having passed on Earth then you had experienced. If you stayed on Earth you would long previously have died of old age. (this is obviously a thought-experiment )

In both cases, the passage of time as experienced by the observer is in relation to their relative position over time to the clock.

Dont think too hard about this stuff, I have *literally* seen people go mad thinking about it. (An ex-lecturer of mine!)

DeV.

Gargoyle

Originally posted by DeVore
That is pure theory though. Noone has ever shown that while space-time may be curved near large mass objects, it can be curved MORE to facilitate some form of *hop* between locations.

Frankly, speaking as someone with a degree in Pure Math, I find the area somewhat more fanciful. I dont object to the discussion of the topic in Science but I dont believe that what was a good analogy by Einstein (of the rubber mat with a lead ball on it) should be taken as literally as it has been in some sci-fi authors books.<snip>

Speaking as someone with a degree in Physics, DeVore is correct. People have gone crazy on wormholes not reaelly because they can be explained by general relativity, but rather because it's not explicitly elminated.

Most physicists believe that if a wormhole were ever to be created artificially, you'd have to do it from both sides, making it pretty useless for exploration. Additionally, most believe that you'd hardly get anything much larger than an alpha particle through it even if you did create one. Of couse, this is all science, most definitely not engineering. But, its fun to discuss nonetheless.

Bob the Unlucky Octopus

This discussion is leading us straight into string theory in all its complicated nastiness. Let's first start off with the idea that a black hole must emit radiation, a fact that was proved by Hawking.

Let us first, consider the Heisenberg uncertainty principle:

delta (x) * delta (p) ~ h/2pi

This is equivalent to the expression:

delta (E) * delta (t) ~ h/2pi

Now, the universe allows for the creation of a proton/antiproton pair, that annihilate each other a very short time after they are created. However, if this happens near the event horizon of a black hole, either the proton or the positron can be absorbed before they had the chance to annihilate each other. Since we have a black hole absorbing borrowed energy, it must emit it somewhere else. This predicted radiation is called Hawking radiation.

That is as far as reliable proof takes us. Ideas like white holes, wormholes, bending of space-time are all just conjectures really, means of explaining how and where the radiation is emitted. We have no idea what would happen if any of us approached a dark mass/black hole, or where we would be emitted if we avoided total destruction[tm]. In fact, you'd almost certainly be crushed into particles not found anywhere else. Saying a small amount of proton/positron radiation is emitted, and then trying to expand that idea to a large mass (even larger than a few particles) is ludicrous and unsupportable. A partial and and almost impossible to prove explanation is found in superstring theory, a theorem which makes perfect sense mathematically, but is impossible to verify at the current time.

Now it's incredibly elegant mathematically, and if any of you wish to pursue this further, here's a great link to start at:

http://superstringtheory.com/

A simple explanation of Hawking's radiation is found in a nice little animation at : http://superstringtheory.com/blackh/blackh3.html

A more complicated explanation for the mathematically inclined, outlining the Four Physical Laws of Black Holes is found here:

http://superstringtheory.com/blackh/blackh3a.html

For the rest, just navigate the site, it's extremely interesting, and well worth perisisting with the math involved, particularly for those of you who have mathematical training in the first place (DeVore, bonkey, et al).

This debate is to be perfectly honest, extremely difficult to hold on an internet board, mainly because of the highly complex ideas involved. There are perhaps in the order of magnitude of 50 people on the planet who can claim to understand string theory. As such, it makes it hard for us mere mortals to discuss these concepts intelligently. We'll give it a try at any rate

Occy

bonkey

Originally posted by Bob the Unlucky Octopus
This discussion is leading us straight into string theory in all its complicated nastiness. Let's first start off with the idea that a black hole must emit radiation, a fact that was proved by Hawking.

However, Hawking's proof also shows that a back hole can shrink because of this, and that the more it shrinks, the hotter it gets. Ultimately, his proof shows that black-holes should shrink "to nothing" while still remaining as singularities, but when their mass gets to about that of an asteroid, they would be emitting msasive amounts of energy.

This, unfortunately, disagrees with observation, because we have never observed anything approaching this amount of rediation from any body.

It is worth remembering that anything dealing with black holes is a major problem, because it involves special relativity and quantum mechanics, and at the moment, those two theories are incompatible!

Interestingly, horrid string theory shows that in certain cases, these "extremal" black holes would not in fact emit radiation.
Of course, as with anything in string theory, this i sspeculative. The whole field of string theory is too young to be considered a solid model yet, but it does show some interesting stuff...

Now, the universe allows for the creation of a proton/antiproton pair, that annihilate each other a very short time after they are created.

Is it not virtual photon / anti-photon pairs (as opposed to protons, which are not elementary particles).

To those not familiar - this is based on quantum theory which states that these particle-pairs can exist briefly, as long as they "repay" their energy to the universe quickly. So, in normal conditions, nothing splits into a virtual particle/anti-antiparticle pair which then quickly recombine to nothing. In theory, they do not have to recombine with each other, as long as something is "destroyed" quickly enough to repay the energy debt.

In a tiny area around the event horizon of a black hole, this could (and should) lead to a number of situations where one half of the virtual pair falls into the singularity, and the other escapes. Thus, a particle has been unleashed into the universe "from nothing", and the black-hole pays the energy debt! Thus, the black hole appears to be radiating energy....which means that it has temperature, and also that it is *losing* energy, and therefore shrinking.

The problem with this theory comes (as mentioned above) when the black hole shrinks below the Chandaskar limit (if I have my names right) which is the minimum mass a collapsing body needs to form a black hole. See, you need the mass (in theory) to build a black hole, but once built, it can apparently shrink smaller and smaller because of the maths involved. However, as it shrinks, it should emit more radiation, for some perverse reason, despite the area of its even horizxon having shrunk.

Anyway - back to wormholes...

Lets start with the startrek notion of time-travel.

First, if wormholes exist and we could travel through them, they allow what is apparently FTL travel, but not time-travel. Let me explain. If you set off from point A, and head to point B via a wormhole, you will arrive there faster than any information transmitted at light-speed from A at the moment you left.

However, this is not the same as time-travel as you can never get back to where you started before you left.

So, first off, to make sure no-one wanders off into startrek science on this thread....time travel is not possible via wormholes by any of our existing theoretical models, including string theory, because in all of them, the wormhole is a tearing of a spatial dimension, and there is no theory which allows the tearing of the time-dimension. So no time travel. Got that? None.

Now, FTL travel....

If wormholes exist, and it is possible for us to travel through them, is FTL travel possible? The short answer is "unlikely". Why? Because as far as I can remember :

Relativity theory does not allow for the tearing of space-time and has no model to show what the impact would be.
Quantum theory does not allow for the tearing of space-time above planck length which is too small to "go" anywhere.
String theory does allow for the tearing of space time, but only in the 7 (or 8) rightly curled dimensions which we cannot see (known collectively as a Clabai-Yau space). While string theory does not limit the tears exclusively to the CY-space of the hidden dimensions (which, by the way are curled at or smaller then Planck length), there is no model yet developed to show that they are or are not possible in the larger dimensions adn what the impact would be.

In other words, all of our models that allow wormholes show that should wormholes exist, they dont actually span the universe, but rather exist on scales so tiny that they can effectively be considered to have their entrance and exit in the same place (from a macroscopic point of view)!

Of course...these holes are so small that even if they do exist, we cant travel thru them cause we're not as small as Plack length, which is the largest a wormhole could be without having catastrophic impacts on the physics model observed within our universe!

So....

with a vague understanding of the current models, I hereby proclaim that anyone advocating wormholes is looking at showing a way that they could exist by *modifying* our existing theoretical models, or by coming up with a new model entirely.

They may not be wrong, but it is highly speculative.

This make sense to anyone?

jc

Gordon

(over my head)

sorry to interrupt, this is very interesting.

Sir Digby Chicken Caesar

aye, tis am gona go read that superstring site now

course I say that now, but i have said it about ten times already i always get bored and go back to IRC

oh btw, DeVore ... deg in pure maths
you bastard


Mordeth the envious

bonkey

Pure maths....bastid. I only have a degree in Applied Maths. Bah.

Right...thats it....I'm going back to uni

On a more serious note.....

If anyone is interested in reading a bit about string theory, I find The Elegant Universe by Brian Greene to be the most readable intro to it I have come across, because he does a great job of keeping in touch with the Relativity and Quantum models, and showing how string theory explains the common stuff, and may offer solutions to the incompatabilities of the two main models.

Chapters 13 and 14 in this book (where I am at the moment!) discusses black-holes, wormholes, and all that good stuff. In fact, I probably would have kicked off a thread soon about the whole area anyway. Once I digest the info properly, I will probably write something up anyway.

jc

][cEMAN**

Hmmmmm I always prefered applied maths to pure maths at uni - I did both yet only have 2/3 of a degree. 1/2 of my masters....

The worst thing about it is that I forget it all - I looked at that site Occy put up on string theory and new that I should have recognised all of the types of equations but couldn't. Damn attention span of a......anyway what was I saying?

Saruman

Bone collector, you say time travel is beyond our technology.. this is true mostly yet proof of the possibility is within our means. For instance the 2 Atomic clocks, one moving on the ground the other moving at high speed on concord, The one on concord arrives and has lost fraction of the time it should be at compared to the one on the ground.. answer.. faster you go the less time passes. We are only talking a fraction of a second here BUT it shows its not impossible, but then again i doubt anything is actually impossible, after all did the universe appear in the big bang or in laymans terms Everything came from nothing.. (i wonder what that nothing was like!)

Bob the Unlucky Octopus

Saruman, it's impossible to exceed the speed of light, and therefore impossible to "time travel" or to "run time backwards". It'd take an infinite amount of energy to accelerate to this speed, logically, more than an infinite amount of energy would be required to accelerate past c. In conclusion, it's not possible as far as we know.

Occy

PS- I'd be grateful if people did a bit of reading around the mechanics of simple relativity before posting in this thread- "A Brief History of Space and Time" by Hawking is an excellent introduction to modern physics.

DeVore

1. the clock runs slowly.
2. the clock does NOT run backwards.

3. the faster you go the slower the clock SEEMS to go.

4. At the speed of light it would stop proceeding at all.

we theorise (rather simplistically) that if extrapolate this data (faster speed = slower time) that if we exceed light speed time will start going backwards. Quite a logical jump...

Cute idea and unassailable since we cant test it.

DeV.

JustHalf

Hey DeV

Any good books/website to look at for learning degree-level maths? I find maths interesting, but it's not something I can learn from lectures (these being dull as hell)... but I'd like to increase my maths capability.

bonkey

Originally posted by DeVore
we theorise (rather simplistically) that if extrapolate this data (faster speed = slower time) that if we exceed light speed time will start going backwards. Quite a logical jump...

What must also be remembered when looking at issues like this is one very simple fact :

Infinities have never been shown to be permissable in nature

Why is this relevant to the discussion at hand?

It is considered by most that breaking the speed of light is impossible because again, an infinite amount of energy would be required (under special relativity) to accelerate something to c.

Something without mass cannot have its speed modified by any method we are aware of, so were are only talking about massive particles here (where massive means "having mass" as opposed to "huge").

Now, those who believe that breaking the c barrier is possible are looking at it from a quantum point of view. At a quantuim level, the "smearing" of hte uncertainty principle could in theory allow a massive particle to travel beyond the speed of light without the problem of infinite energy. The maths can also be manipulated to show that beyond c infinite energy may no longer be required.

If this is correct, then individual particles, at a quantum scale, can in theory break the speed of light. However, no observation has been made to verify this theory.

Now....before the trekkies start yammering on about how time-travel must be possible if this second theory is correct, please keep reading....

Individual particles is what the theory discusses. Not objects. Not even atoms. In the same way that quantum tunelling does not mean that we can walk through walls, >c quantum particles does not mean that we can time travel.

Put simply, there is absolutely no mechanism anywhere in science which can be manipulated to show that anything larger than a single particle can do "weird things" like tunelling, time-travel, etc. and furthermore, there is no known way for us to control particles to do these things, because they all rely on the "smearing" effect of quantum uncertainty.

jc

Cake Fiend

Pff, lightspeed? Everyone knows you can travel through time by going 88mph in a DeLorean...

bonkey

LOL. How could I have forgotten.

Right - throw out science, and bring back Deloreans

jc

Saruman

yup that's true but you cant just pop down to your local peat's or Mapplin and get a flux capacitor can you, come to think of it De loreans are hard to come by too!

On another note sure you cant travel to the speed of light under the current laws of physics. However, im sure there have been impediments like this in the past and the laws of physics have been bent! If you cant travel faster than the speed of light then find someway to bypass having to move very fast at all which comes back to the whole wormhole thing! (nothing to do with time travel here!). there must be some way to open up a spacial rift (for lack of a better word) of some sort and move from one point to another with nothing more than a step through.. Hey it would beat the traffic gridlock in Dublin!

nesf

Originally posted by bonkey


Infinities have never been shown to be permissable in nature

Nice but debatable. I would agree, but to "model" certain situations, one may use infinities...

Thats where the problem lies. No number is permissable in nature in a strict sense. It's only in the models that we can discuss such things as the permissability of numbers and such. I know I'm being pedantic, but I'm trying to be very accurate in my for my next statement.

Take the idea of a Fourier Transformation, (apologies to all who've not come across or studied this concept), one can take a non-oscillating body and describe it using a fourier transformation with a period of infinite lenght. I know this is not quite what you were talking about, but i'm trying to get across the impossibility of completely banishing infinities from models. Look at re-normalisation in quantum or QED for instance.

Short answer to this is, I'm saying that we can't make broad far reaching statements (no matter how reasonable they may seem, about what is not permitted theoretically about nature, since tbh we still haven't figured it all out yet (assuming if we ever will for that matter.)

That said I pretty mush agree with your statement, I'd just like you to clarify and state it in a more precise fashion


In responce to Saruman, you cannot claim that the light barrier can be exceeded because of previous barriers being passed before. At a macroscopic level, relativity theory seems to be very accurate, I do agree with DeVore that it is misinterpreted at times, exp by popular physics authors, but we can't dismiss it, merely because we'd like a better result.

we theorise (rather simplistically) that if extrapolate this data (faster speed = slower time) that if we exceed light speed time will start going backwards. Quite a logical
jump...

Cute idea and unassailable since we cant test it.

Hmm, actually at FTL time would appear to go backwards to observers at sub-light speeds, but the opposite would be true for an observer traveling (from our observations) at FTL speeds. The tachyon problem can be introduced here. Particles have been found (a type of muon if i remember correctly, but I'm open to correction, I read this years ago), that exhibit tachyon properties. That being, that their behaviour is only agreeable with the physics of our universe if they were moving back in time in relationship to us. (Theres something about time symmetries(sp??) that comes in here but I can't remember what exactly, I'll see if I can find out tho) These particles have been observed from cosmic ray collisions with the athmosphere, and not in the lab, as the energies required are unfeasible etc.


One must take into account that the Theory of Relativity allows FTL, it just forbids going from STL to FTL speeds. It's one or the other, and due to symmetry etc, it should be a mirror image to our present frame of reference, only with the time flow, apparently being reversed.


I'm open to correction on this tho. I'll see if I can find some sites on the matter, or some books to read on the topic. Although it'll probably have to be a technical book (iow v v expensive) to actually cover this fully and have enough maths to suffice all the hungry maths grads in this thread...