Science Fiction Writers Workshop

[quote]Kip Thorne proved back in the 80's that time travel is possible.[/quote]

So by "proved" you are saying he did it? He actually built this infinite X 3 machine?

No?

Hah!

I rest my case. If it's all on paper, it's not much of a proof.

The major "proof" that time travel cannot happen is the paradoxes it creates. The old chestnut: if you go back in time and kill your parents, you will cease to exist, but that means you didn't kill your parents.

The Hitchhiker's Guide to the Galaxy (an unassailable bastion of scientific theory) gets around this by saying you are still here, therefore you didn't kill your parents, therefore there is no paradox. This seems reasonable because how many people could actually go through with it?

However, something simpler, like going back in time and buying Cisco stock at the IPO, or going forward in time to find the winning numbers for some lottery, anyone could do with few moral roadblocks. Or even going back in time and asking that girl out that you just didn't have the courage to do. What's the harm in that?

Or here is another one. Say you invent a machine that sends a message back in time. Just a message, something simple.

So you ask your friend a question at 3:00, he sends you an answer at 2:00, and you get the answer at 1:00. Therefore, you got the answer 2 hours before you sent the question. You don't need to send the question anymore. That means you won't get the answer... You have a paradox.

The physicist you postulated that experiment said the universe would split into two halves, one where you had the answer, and one where you didn't. Thus time can fork just as space can.

That means the universe consists of an infinite number of parallel universes where all possibilities exist. If you go back in time and change something, you will from then on be in a different universe.

In other words, to put in layman's terms, these physicists haven't a clue what would happen.

[quote="eddycurrents"][quote]Kip Thorne proved back in the 80's that time travel is possible.[/quote]

The major "proof" that time travel cannot happen is the paradoxes it creates. The old chestnut: if you go back in time and kill your parents, you will cease to exist, but that means you didn't kill your parents.

In other words, to put in layman's terms, these physicists haven't a clue what would happen.[/quote]

Well....Kip Thorne proved it mathematically

But if you want to talk time travel I have to say that the talk about paradox is hogwash. Its an idea that stems from Newtonian thought about a clockwork universe where everything has a begining, middle, and end. Where rules are clearly defined and boundries easy to seperate.
There is only a paradox if you assume the universe itself follows the human mind's "arrow of time" which filters all events so they appear to be orderly and follow the premise of cause and effect. One of the things that relativity did, aside from throw Newton of his gravity throne was point out that even time is relative. From the universe's point of view there is no distinction between past, present, or future. As Einstien was fond of saying, there is only "here now", and "here then." Here now is obviously the moment you think you live in. Here then would be any other time.
Also from a quantum mechanical point of view there is no difference betwen a particle traveling backwards in time, and one moving forward in time. The Universe would treat them as the same (assuming of course we're talking about say two electrons, or two protons, et. Of course different particles would be treated differently.) There is even a theory that was breifly considered feasible in which every electron in the Universe could be thought of as being merely one single electron, at various stages of temporal movement. Sometimes moving forward, sometimes moving backward. Don't know how fashionable the idea is now...it was mostly popular with old Soviet physicists and made some great Soviet science fiction stories

The likely truth is that the Universe is a chaotic system where cause and effect aren't as closely adhered to as our human sensabilities would have, where time travel would and probably does ad a level of complexity to the chaotic nature of the universe.

The idea that every choice we make creates a parallel universe has become a bit passe' in physics today mostly because quantum theory is evolving into string, or brane, theory. In string theory particles are seen as oscillatingg membranes at sub-sub-sub atomic levels. How the brane oscillates determines which particle we percieve at our level of perception.
Also in string theory, time plays a less structured role. Oscillations can travle forward or backwrd in time, and depending on when we observe them will determine if we see say a quark, or a proton. Admittedly my string theory is weak at best, and I'm still learning, but my point is that from a 21st century physics point of view, time travel paradoxes are moot. Douglass Adams may have been right after all....

And yes....physicists haven't a clue, that's why they need science fiction writers to show them the way

Joe's argument makes sense.

Note that when you transmit information, you are transmitting energy. If you can transmit energy, you can transmit matter, because they are the same thing. That's assuming you can reduce matter to pure energy and somehow contain the supernova that would create.

...

Here's another thought: if you say time and space are inseparable (Einstein) then just as a body can't be in two places at once, a body can't be in two times at once -- as it would be if you traveled back to a point in time where you already existed.

That means you could still travel to some point in the future or distant past, but only once.

How about if you jump backward in time and find yourself. How is that possible if you don't remember it in your present time?

And what about if you travel to five minutes in the future, then go back to your original time. What happens in five minutes? Will you see yourself? What happens if your future self is standing on the exact same spot where your present self jumps to? If that negates your present self, how do you get back in time to create your future self?

So here's an interesting slant on a time travel story: you can only travel to any point in time where you know you did not or will not exist. If you try to exist twice at the same time -- something very bad happens.

[quote="eddycurrents"]Joe's argument makes sense.

...

Here's another thought: if you say time and space are inseparable (Einstein) then just as a body can't be in two places at once, a body can't be in two times at once -- as it would be if you traveled back to a point in time where you already existed.

That means you could still travel to some point in the future or distant past, but only once.

How about if you jump backward in time and find yourself. How is that possible if you don't remember it in your present time?

And what about if you travel to five minutes in the future, then go back to your original time. What happens in five minutes? Will you see yourself? What happens if your future self is standing on the exact same spot where your present self jumps to? If that negates your present self, how do you get back in time to create your future self?

So here's an interesting slant on a time travel story: you can only travel to any point in time where you know you did not or will not exist. If you try to exist twice at the same time -- something very bad happens.[/quote]

But....(cause I love playing Devil's Advocate, and I'm on vacation, and I'm really, really bored, and I should be writing but every time I try someone interrupts me...)

If the Universe is a chaotic system and by this I mean as in the science/math of chaos theory what would be the problem with two similar, but slightly different objects occupying the same time? After all, you aren't exactly the same mass, or same density as you're younger self. There are differences. Changes due to age might make a big differnece in how the Universe sees us at different times. And we don't know all the rules yet. Maybe a body can be in two places at once. After all if two particles can be linked quantum mechanically over a large distance (this is the premise of entanglement) then as far as the Universe is concerned those particles are one.

I think our perception of time, and space will have to be adjusted.
In my humble opinion I think that if we meet our past selves, all that will happen is that we meet our past selves. I think the Universe is rich in texture enough, and complicated enough to be able to shrug off any postential paradox that arise because of some sentient who thinks he's figured out a loop hole.

My love for science fiction is deeply rooted in the premise that there are lots of loop holes that we can take advantage of. Ian Watson? Ian Wallace? One of the Ian's at any rate had an FTL dive that was essentially a time machine...he had his folks travel back in time to when the Universe was smaller and cross the distances more quickly.
Niven had an FTL drive that combined hybernation and time travel:
Travel back in time say five hundred years, go into hybernation, slow travel between the stars...at the destination the ship computers wake you from hybernation. AS far as you're concerned it was an instantaneous trip.

But I do like the idea of something bad happening to you if you're out of your time. I've been fiddling with a story for awhile now along those lines. Suppose multiple world lines are possible. Supposse someone crosses to another time. What if they shouldn't be there and the Universe recognizes the difference? What if the person starts to get unexplainably sick?
You know all those weird dreams we have about strange places?
All those unexplained pains and aches you feel that no doctor can ever explain. What if you're in the wrong time and the Universe is trying to kill you, and you can't get back to youre own place because you don't know how you got to this on to big with?

That's the premise, now if I can just write it!

Hmm...

Webster sez:

equivalent = equal in force, amount, or value
equal = of the same measure, quantity, amount, or number as another (synonym EQUIVALENT)

[quote]would that create some sort of imbalance?[/quote]

Theoretically it would. The big-bangers say that all matter (and energy since they are the SAME THING) existed at the point of creation, and all we are seeing now is a redistribution of both and conversions of one to the other.

Here's another paradox: say you had an object that you took back in time and gave to yourself a year ago. That means that object only exists for one year. Thus it didn't exist at the big bang. Did you create something out of nothing?

Hawking sez time before the big bang means nothing, because time started at the big bang along with matter/energy as we know it. I think in a roundabout way that proves my paradox.

[quote="eddycurrents"]Hmm...

Webster sez:

equivalent = equal in force, amount, or value
equal = of the same measure, quantity, amount, or number as another (synonym EQUIVALENT)

[ :?[/quote]

Well...yes...but obviously you didn't read the rest of what I said, or what you said. You said they were the SAME thing, which is not what Einstien said. Equal in value or amount or force is not the same as being exactly the same THING!! Photons do not act like protons. They can't. They are different particles. But, a clump of protons might be equivalent to an amount of energy which happens to effect spacetime the same way.
Webster's dictionary doesn't answer physics questions.
For that you need a physics dictionary.

here is a good link:
http://www.geocities.com/thesciencefiles/emc2/emc2.html

Note that what E=mc2 actually implies is that matter and energy are two different STATES of the same thing, NOT THE SAME THING!
In physics, that's a big distinction. Just as solid water behaves differently from liquid water, or a liquid hydrogen has different properties from gaseous hydrogen, matter and energy behave differently. It does not automtically follow that because you can do something with energy you can do so with matter. Matter has density, and requires less volume to warp spacetime then is required of energy to do so. To create a gravity well using only energy will require concentrating an enormous amount of energy into a very small volume of space.
Perhaps...getting back to mt original repsonse to your thought that what you can do with energy you can do with matter, just perhaps time travel involving matter requires too many possible cariables to make it easy.
Or maybe sending matter back in time results in complete conversion of said matter to energy. In which case...boom.

I founf two sites that had a good discussion about time travel.

http://www.pbs.org/wgbh/nova/time/

and

http://www.physicscentral.com/writers/writers-02-4.html

Which Niven story was that?

Energy or matter can carry information. Assume you have two identical systems. You then add information to one of them. Has its mass increased? I take a sheet of paper and give it to my grandson. At two he manages to scrawl a few lines on it. I take an identical paper and using the same amount of ink I write Maxwell's equations. Have I created mass/energy?

I never heard of a law of conservation of information. Scientific American had some articles a few months ago where they were describing a computer that used no energy (? something like that) I think they said that it takes energy to destroy information. It was some kind of thermodynamics argurement, never my strong point.

Oh well, fun to talk about.

[quote="DaveK"]
Energy or matter can carry information. Assume you have two identical systems. You then add information to one of them. Has its mass increased? I take a sheet of paper and give it to my grandson. At two he manages to scrawl a few lines on it. I take an identical paper and using the same amount of ink I write Maxwell's equations. Have I created mass/energy?

Oh well, fun to talk about.[/quote]

Yes fun to speculate and talk about. Science fiction writers can do that, scientists can't...hah ha...

I would say that if you add ink to a piece of paper you are adding to its mass. If I eat too much food, and only a portion of it gets released as refuse, I increase my mass, right? (trying hard not to confuse weight with mass)
If the paper's mass consists of a particular number of atoms and you add more atoms by putting either scratches or equations, you, by my arguably flawed mental reasoning add to the paper's mass. From this perspective I would say sharing information can increase mass. As for energy...hmmm

If you and I set up a sytem for sharing information which say involves changing an electron's state from postive to negative, and we both have instruments which let us observe these changes and interpret them, and we establish a code whereby postive means one and negative means zero, and we use this binary code to convey our messages/information we might be adding energy to our systems if the mechanism by which the electrons are flipped requires jolting them with photons. hmmm Hitting an electron with a photon will bounce its energy state and create another photon. maybe that's a bad anaology. That might just keep the level of energy the steady. Have to ponder that one some more..

As to a law of Conservation of Information, I kind of cheated a bit. The concept of such a law is where the controversy lies. Some folks think there must be one, some think there can't possibly be one. That's why information escaping from a black hole is important.

Here is a link to a paper discussing if such a law even exists.
http://arxiv.org/abs/gr-qc/0108010

I won't even begin to jump into the main fray of this conversation but to toss in these Timetravel stories I've recently read. 1) From Asimov's is "Chop Line" by Stephen Baxter in which Humans are battling a war by traveling to the future to see what happens. Then returning and doing things to change or alter the future. Then they return to the future and do it again and again and again. There's a huge complex dedicated to peering into the future to alter "present" events to help win a Human alien war.
2) A novel, called The Female Man, by Joanna Russ. This is one tough book. Major Fem-lit, but the timetravel ideas are pretty cool. I think this was written in the 60's and the ideas were pretty revolutionary: Something like you can't travel back in time to your own world, but you can travel to an infinite number of universes and alter those. I called the "X" theory because you couldn't travel in a straigt line, but only to a "neighboring" universe.

[quote]Matter has density, and requires less volume to warp spacetime then is required of energy to do so.[/quote]

You mean matter [i]is more dense[/i] than energy, and therefore requires less volume to warp spacetime then is required of energy to do so.

I don't know if that's the case, but I won't disagree with you. However, it doesn't matter (groan). Energy still has mass, and still warps spacetime, just as matter does. Einstein said in effect matter is compressed energy.

Now with all the quantum physics that have come since then, we are now talking about quarks and strings and other strange charming things (another groan). And some people have the GUTS (oh stop it already) to try to explain all the different particles and forces.

I don't understand all that. From what I hear, most quantum physicists don't either. But the fact that energy has mass has been proven, first by watching starlight bend around the sun during an eclipse.

Last I heard, they found even neutrinos do indeed have mass. And the GUTS folks are trying to use particles to explain forces, and I expect those particles will also have mass.

So if you are agreeing that energy has mass, but saying energy is a different form of matter -- I can align with that.

So long as we are clear... whenever we say energy, we are also talking about mass.

So back to the thread... Do we want to send matter in time, or just information?

You could easily argue that any form of information requires mass. If someone says "the sun will rise tomorrow", that required energy (which has mass) for him to say that. Even if you just think it, that still requires energy.

Even the lack of information could be considered information, but that still requires energy. If absolutely nothing happened in the universe for a microsecond, that's interesting information, and you had to burn energy to live through that microsecond to be able to process it.

This is because it's only information when it's read and processed by something (oops, now we are getting into Zen).

So does that mean you can [i]transmit[/i] information [i]without transmitting mass[/i]?

Dunno. You would need to be able to manipulate something in one time by doing something in your time, like some kind of parallel universe harmonic. Then you wouldn't actually be sending anything back in time. (Unless the harmonic thingie requires a force, which makes sense, and GUTS says forces are really a kind of particle, and if all particles have mass, we are back to where we started.)

The parallel universe idea is kind of the argument Crichton uses, and it's based on quantum theory (you would have to read the book).

However, Crichton extends this quantum shiznit to also send mass back in time.

Then even if the theory works, uh, in theory, you still have paradoxes, whether sending information or mass.

For information, there is the paradox of sending answers before the questions, which I mentioned earlier.

For mass, there is the paradox of an object which exists only for a period of time, which I also mentioned earlier.

A truly convincing time travel story would explain how to get around these paradoxes. People are willing to accept a story without it, just as people are willing to accept FTL travel without full explanations if the science is otherwise solid. Still, I would like to see a truly convincing time travel story.

One way to get around these paradoxes by using infinite parallel universes. So if you change something in the past, it doesn't necessarily change your universe -- it changes others, or puts you into that universe. This is kind of the approach Crichton uses.

Even this is pretty hokey though.

Dude... I was groaning at my own bad puns. Not at anything you said.

My immature FTL comment was the same -- an attempt at levity that backfired.

You can bury me in any science discussion. I have always been impressed with your broad background and detailed posts. I was just trying to stimulate argument and keep the thread going. Hell, I was trying to keep up with you!

No offense was intended at any time during the aforementioned posts or emails.

No offense shall be intended at any time during future posts or emails.

Don't go. If anyone should leave the group, it's me.