The New Question

[Astro Dave]

Here is a question I've posed to my students over the years. Please read the question carefully.
BTW - We need to divorce ourselves here of any constructional hurdles. This is purely a 'thought experiment'.

We have found intelligent beings on a planet 1,000 light years away. To commmunicate between us a message would take 1,000 years both ways at the speed of light. Obviously a useless way to converse.

Now, a new idea has been introduced: Between us and them is a long rigid pole. It touches both planets. If I tap on the pole at my end, I should be able to send a message to the people at the other end instantly by say, morse code. Dot dot ... dash dash etc. We've beaten the time gap.

Yes or No?

[Radar]

I don't think the vibrations could travel faster than the speed of light. And with the expansion of the universe the pole would need to keep getting longer and longer to reach both planets. Also the tapping on the pole may need to be so hard that no pole could withstand such force. :pipethinker:

[CanisMajorTom]

What is the pole made of?

[Astro Dave]

Good efforts so far guys. Tom, let's assume the pole is simply a solid piece of say, steel. For the argument it doesn't matter that much, as long as it is basically a solid structure.

Radar your assumptions are correct. The vibrations could not travel faster than the speed of light. BUT I anticipated such a response from you and have factored in a tangent:-

What if I now push the pole forward? I could use one push, or a series of jabs. They would feel that at the other end. I could still use the morse code system to communicate in real time. I have negated the time delay factor.

Who has an answer to this conundrum?

[Robert TG]

A pole 1000 light years long. Wow, depending on it's diameter and density... is there enough material in the universe to build this. LOL

I agree the answer is no because pushing this pole would still condense the atoms in the pole as they expand again the compression wave would still be slower than the speed of light.

[Tenacious Del]

If the pole was made to a standard where there was no compression wave, then it could be possible to communicate faster than the speed of light. :hmm:

[Radar]

I just had an epiphany.

The expansion of the universe would make this impossible, because the distance between the two planets is increasing constantly so the pole would have to keep getting longer in order to be used for communication. :hmm:

[AstroBob]

I don't think there would be expansion between planets? The gravity of the milky way would hold us together at the same distance I'm thinking. :hmm:

[Jimbot]

I don't think there would be expansion between planets? The gravity of the milky way would hold us together at the same distance I'm thinking. :hmm:

Well Bobby has a point about us being in the same galaxy. But remember that the push on the pole would be a push on the earth as well, and given that our pole is 1000 light years long and therefore would have a mass greater than the earth the earth would move rather than the pole so no intantaneous message transfer I believe.
:pipethinker:

[Robert TG]

I found this information on the subject...
"If you have a long rigid stick and you hit one end, wouldn't the other end have to move immediately? Would this not provide a means of FTL communication?

Well it would if there were such things as perfectly rigid bodies. In practice the effect of hitting one end of the stick propagates along it at the speed of sound in the material which depends on its elasticity and density. Relativity places an absolute limit on material rigidity so that the speed of sound in the material will not be greater than c.

The same principle applies if you hold a long string or rod vertically in a gravitational field and let go of the top end. The point at which you let go will start to move immediately, but the lower end cannot move until the effect has propagated down the length at the speed of sound in the material."

[Radar]

I think Jimbot may have nailed this one. Robert, Dave is he right?

[Astro Dave]

In essence, most everyone's right, in a roundabout sort of way.

The whole issue revolves around moving information - whether it be verbal, written or mechanical - instantaneously. Forget planets moving apart and the expansion of the Universe... that does happen of course but for this exercise we're only interested in the actual transmission of information over a vast distance without the time delay.

A rigid pole between two points a thousand light years apart is a thought experiment. Einstein invented the term 'thought experiments' because he thought it was a good idea to do that. (No he didn't I just made that up)

We do thought experiments when mechanical constraints prevent setting up some sort of testing mechanism, and to remove all superflous 'facts' that don't affect the outcome attached to the question.

You cannot just push or tap on a rigid pole between two young Luke Skywalkers 1Kly apart and have the effect felt at the same time. NOTHING, mechanical movement or vibrations incl. can exceed the speed of light, the speed limit of our universe. If you pushed/tapped on the pole it would still take 1000 years for that effect to turn up at the other end.

BUT - There may just be a way to do it. It's only new science, but it looks promising. There is something about to be tested that may hold the key to FTL travel. There is something which, if experiments prove positive, may be the mechanism to allow us to send information instantly, to any point in the Cosmos.

It may even reveal to us, for the first time, proof of dimensionality!

Anyone care to hazzard a guess what it might be?

[Jimbot]

In essence, most everyone's right, in a roundabout sort of way.

BUT - There may just be a way to do it. It's only new science, but it looks promising. There is something about to be tested that may hold the key to FTL travel. There is something which, if experiments prove positive, may be the mechanism to allow us to send information instantly, to any point in the Cosmos.

It may even reveal to us, for the first time, proof of dimensionality!

Anyone care to hazzard a guess what it might be?

Well sounds to me like string theory!! Entangled strings may be able to transfer information instaneously but the issues for it relate to how to "encode" the information without altering the entanglement. I think that is how it works.:duh:

Jim:pipethinker:

[Astro Dave]

Well done Jimbot!! Well done for having a go. No - not directly related to string theory, sorry.

[Radar]

Super positioning?

[Astro Dave]

Nope Radar .. you're not near it. Good try though.

It is a new concept based on a suggestion for the existence of 'something' by Mr. A. Einstein (who pinched the Theory Of Rel by the way) a long time ago.

Think in the area of Black Holes/Neutron stars etc

[Duncan]

I'm led to believe the answer here might be in bending space and time by gravity waves. Anyone else got a thoughtie.:pipethinker:

[Astro Dave]

Ok, well done Duncan!! After pondering your answer, quite a few times I might add, over a good glass of milk (Yeah right!) I've decided you are so far in the ballpark you might just run into the batter.

It is mused (look that up) that gravity waves may in fact travel at enormous speeds, read that as instantaneously ... not constrained by the light speed barrier.

This is pretty heavy stuff - like U238. (look that up too)
There is a lot in this subject so go look it up.. try looking up "the speed of gravity waves" on Google. I saw this research presented in a paper presented at a symposium a few weeks ago.

It means, in essence, if all this tests out, communications from one star trek voyager to another won't suffer the time delay problem. Whew!!

Now, where did I put that glass.....?

[Duncan]

G,day Dave,
Hope everything your way is fine.
It certainly is an interesting theory. I would guess that it has even been asked if anything can be attached or dragged along by these. If it ever does become possible then think of the possibilities. Not just in space but even here on Earth. It's not that i'm particularly intelligent i just like scientific things,and have a reasonable memory for them. But i can't remember what the missus said 5 minutes ago,lol.
TIME TRAVEL,well not in my lifetime. But then again they said we'd never walk on the moon either.Certainly something to ponder.
Cheers mate,
Duncan:pipethinker: :pipethinker:

[Astro Dave]

Hi Duncan

Never, never, ever knock yourself because of your limited knowledge. The mere fact you are posting intelligent and incisive questions puts you out of the 'low intelligence' category.

You're better than you think you are.

You, and several others, are feeling your way over some pretty corrugated ground. Real estate that I (and a few others I suspect) walked on a little while before you.

By putting forward your opinions you are seeking answers - when it comes to stuff like string theory, gravity waves, dimensonality et al we're al in the dark and no one opinion is more valued than another's, remember that.

By the way: When the new super cyclotrons come online, probably by 2008/2009 they hope to collide (Gold nuclei I think) at the speed of light and produce,... drum roll please, a 'Graviton' - thought to be the particle that makes up a gravity wave. It may also detect higher dimensions as predicted by string theory.

How? If, as they say, the graviton is produced in this nuclear nightmare THEN disappears, it will, according to the hypothesis, enter the 4th dimension!!!!

Now that is COOL man!

[Duncan]

Hi again,

Now that's what i call a super answer. Thanks a million Dave:Chessy_Smile:
Cheers,
Duncan

[Robert TG]

http://www.ldolphin.org/vanFlandern/gravityspeed.html

Very interesting article about Gravity being instantaneous.

Dave, thanks for the hint where to look.

BTW, wouldn't that be the 5th dimension? The physical three dimensions and the forth demension time.

I wonder how long it will be for CERN to give a result after coming on line?

I agree with Dave, Duncan you are thinking about these things which is much more than the vast majority do. Although... you better be sure to listen to your wife and remember for more tha 5 minutes if you value your life. LOL

[Robert TG]

Just had a thought. What if they find that Gravity is another dimension and not a force that is bound by the dimension of time? Therefore Gravity would act instantaneous to us and anywhere in the universe while not "travelling" faster than light through the space-time dimensions.

[Astro Dave]

Thanks Duncan, glad it helped.

Robert, the 5th dimension? ... On reflection - YES (smacks on wrist) that would be more tenable than the 4th (time): heck it could also be any one of the other 5 (10 in total) that pervade the hallowed halls of string theorists.

I like your insightful comment, "What if they found gravity to be another dimension and not a force." I shall chew on that over another glass of cold Milo.

NB/ For the uninitiated, a quick lesson in string/brane theory: Brane theory tells us that our four-dimensional universe may actually be a kind of membrane existing between volumes that contain higher dimensions in space. It says that there could be as many as 10 dimensions of space and one of time. These dimensions exist beside each other and are not penetrable by 'ordinary' means. So, each cannot interact with the other.

In String Theory - Vibrating Strings are supposed to be the smallest things there are, below the level of Quarks and Gluons ... Gluons are thought to 'glue' or tie the quarks together, if I still remember the math I studied on Tattooine.

How they vibrate dictates the type of element it becomes and behaves like.

BUT ... as I mentioned, One thing is thought to be able to move from one dimension to tuther, and that's our friend the 'Graviton'.