(fwd) Where Do We Go From Here?

Please explain this statement. WHY does FTL travel imply time travel?

Because people in different reference frames cannot agree on what's simultaneous.

Here's another explanation that's much better than what I've tried to do:

But both those websites deal with FTL events initiated with a HEAVY tau factor. FTL travel would imply (IMO) that such speeds are unnecessary and (assuming that the arguments posed are valid) somewhat detrimental.

Besides - what we know of the nature of the Universe might not be even a significant fraction of the picture. In decades and centuries to come, it might be determined that Einstein had it totally wrong. :-)

At any rate - that's really an argument for future generations. Me, I just want something that can get me to Mars in a couple of months, Jupiter and the other outer planets in a year or so. Fission drives, ion drives, MHD thrusters etc. can do that, and I don't have to try wrapping my brain around paradoxes...

It implies (forward) TT from the POV of a (relatively) static observer only.

Try this site:

They're not going to find him totally wrong, any more than he found Newton was totally wrong. Einstein's special relativity equations revert to Newton's for low tau.

While we know that Einstein's equations have to be wrong for certain conditions (especially singularities), those conditions are pretty extreme.

In the non-extreme limit, the Theory of Everything will turn into relativity. One of the cool things about string theory is that it demands relativity, although slightly modified for those extreme situations.

BTW: Newton came startlingly close to special relativity. He backed off...possibly because it was just too much for him to accept, possibly because he realized that there was no way he could test it.

Perhaps that's why he became very religious in the last years of his life. I'd like to think it was something like that rather than falling asleep by a concoction giving off mercury vapors or running into a time traveler with a calculator.

Zooty

Can you elaborate?

-dave w

Good one, Bob. Thanks.

BTW: It does mention the "special frame of reference" that I alluded to way earlier in the thread.

This would be a form of symmetry breaking that, alas and damn it, screws up one of the conservation laws. Hanged if I can remember which one.

Kip Thorne has come up with an analysis of wormhole time travel that basically predicts that any action taken would just happen to avoid a paradox. You can travel in time, but you can't affect anything.

This one wouldn't surprise me. It would essentially amount to "you can go FTL or travel in time, but you can't do anything useful with it." My guess is that time travel and FTL, if it occurs, happens like this on a subatomic scale.

I suppose I'd honk off a few people if I pointed out that the subatomic particle theory that predicted tachyons was flawed, and once the flaws were corrected, the tachyons went away....

Oh well.

Zooty

One of the aspects of Newton's laws is that they exhibit symmetry. In free space without gravity, the laws are symmetric in any direction, at least at a macroscopic scale.

(No, I'm not getting into loop gravity theory, mostly because I don't understand it. I can't follow the danged math.)

We have evidence from Newton's writing that he was playing with the ideas that physical laws would be symmetric in any uniform motion reference frame.

Newton backed off. We shouldn't be too hard on him. When you consider that he was responsible for framing the laws of motion which explain everything in his world, asking him to frame the laws of motion for things which he could not see would be beyond belief. Newton was the one who discovered that light has wavelike properties. We tend to think of calculus and physics as being two sides of the same coin. He invented both.

Theologically, he might also have been concerned about the results. People today still take the lack of an absolute reference in space as having theological meaning. There are radio preachers who condemn the theories of relativity as Satanic attempts to undermine the existence of God. No, I'm not kidding. You should hear them go on about Quantum Mechanics. The theory of evolution isn't the only one to get attacked. Newton may have backed off for the same reason.

Heck, perhaps he figured it out, took a look at the mess, realized that people were having trouble accepting the basic stuff he'd come up with, and he simply decided to throw it away and go back to trying to change bass metals into gold using his Alembic.

Maybe he just went out for a beer. I think I'll do the same.

Zooty

It may kill the pun (for those who didn't get it anyway) but it shows how geeky you really are :)

Jerry

I have read Kip's book. It is really good for the layman. Very easy to understand without going into the math. Also, it gives plenty of background to understand how we got to where we are WRT Einstein's Theories.

I actually have a waiting list of friends who wish to read it. They all got interested after I started talking about it.

Bob

If special and or general relativity inply time travel then I believe they are flawed.

does not mean I know something better just that I believe they are flawed.

Newtons laws were shown to be flawed in some conditions by relativity etc.. just like their are implications that it quantum physics proves true that it will prove relativity false in "some" cases.

I ask again show me one test that confirms or even hints that time travel can occur under any conditions.

I fail to see how "speed" can affect time (in the way "WE" want it affected IE going forwards or backwards) not just its speed of progress (slowing down speeding up) and you STILL have failed to take into account that ONLY relative time would be afected if it is at all.

IE time would go backwards for the FTL traveler NOT the FTL traveler would go back in time.

they are two very different statements.

You clearly did not read what I said.

what you said is NOT the explanation for what he asked.

either clarify it or correct it.

INCORRECT or INCONGROUS perceptions DO NOT imply time travel.

AGAIN the ONLY thing they can not agree on is WHEN MY LIGHT IMAGE reached them.

I am not my light image. what I go where I was going is fixed and known. just because THEY are to dumb to account for the light travel distances and times to properly account for when I got their is not my problem and in no way implies ANY time travel under ANY conditions.

The SUn BLOWS UP RIGHT NOW

Yet if you are in africa YOU WILL STILL SEE THE SUN FOR ANOTHER 8 Minutes (roughly)

when the sun blew up is not in question or up for interpritation.

how you calculate that IS and does not imply time travel.

Think of it this way.

Lets say my image travels to you at 600mph if I go 700mph I can reach you and then "watch" an "image" of myself arriving.

I am not watching ME arrive. I am watching an in transit IMAGE of me arriving.

His "relative" Fig Newton got it pretty much right. ; )

Randy

Ok I can by no means do the math. Hell I do not even know what the math is but this page appears so FLAWED that is stands out to me like a sore thumb.

I quote

" However, consider the prospect of FTL travel with this diagram in mind. As O and Op pass by one another, the event "*" has not happened yet in Op's frame of reference. Thus, if he can send an FTL signal fast enough, then he should be able to send a signal (from the origin) which could effect "*". However, in O's frame, "*" has already occurred by the time O and Op pass by one another. This means that the event "Op sends out the signal which effects *" occurs after the event which it effects, "*", in O's frame. For O, The effect precedes the cause. Thus, the signal which travels FTL in Op's frame violates causality for O's frame."

See that LAST part their - Violates causality for O's Frame.

First Their is no casuality for a reference frames. its a contradition by its very existance.

You have casuality period. casuality issue can only occur with REAL instances.

IF casuality APPEARS to be violated in O's frame then this simply means O did not caculate events outside of their time frame properly. Nothing more.

This is going to take a lot of typing so I am going to try it just once. maybe I will make a web pages for it.

First we need a fixed time frame. none of this can even be discussed without that. We will use Earth time as the reference frame from which to compare the other frames of reference.

I travel from here to Alpha Centauri. lets for sake of argument make it 4ly away.

Now lets assume I will do this at 2c or a little over 13million miles per hour.

What is the time line for my trip to Alpha Centauri.

THIS IS THE EVENT. this is FIXED. it is not negotiable. ANYTHING that contradicts this is a MISCALCULATION on the part of the observer. Period.

Now lets try to creat a calculation.

An observer on earth will "see" me arrive 4 years after I leave.

Wrong. the observer will see my LIGHT IMAGE arrive 4 years after I left. he can not see me. we can only see light. this is where peopls confusion sets in.

We can not see anything except light. yes this sounds rediciously obvious but once you really hammer this in all your casuality issues vanish.

you can not see me land on AC you can only see a light image of me landing. Most of the time for our reference points they are effectively one and the same because of how fast light travels. we get confused in this case because now the Object and light are traveling at different speeds.

Now lets say their is a planet 1ly past AC. from time frame 0 (earth launch) when will they see me land on AC ?

one might say well 5ly so 5 years. wrong. its 3 years. 2 years for me to get to AC and then my light image travels from THEIR to the new planet for 1y so

I do not understand why people creat this casuality crap. we already know and accept that the things we see in our telescopes of distance galaxies etc.. happens thousands and MILLIONS and BILLIONS of years ago.

when we look at AC we are NOT SEEING AC. we are seeing a Photograph of AC that is 4years old.

not getting the photograph at the same time to different observers does not imply casuality issues. it is just delivery time.

Let me give you an example that follows your websites example.

I land on AC

6 months later to the 2ly planet I have not landed and while going over their notes they realize that their will be a problem with the landing thruster and I might crash.

so they fire off a message to try and stop me from landing.

well duh I landed 6months ago. no casuality is broken they just end up sending their warning 6months to late since they did not account for Light Image travel time.

No casuality is broken.

Chris Taylor

This one statement, better than anything else, proves that you need to go through a relativity class before we take this argument any further. It's clear you have no significant understanding of special relativity.

Zooty

How geeky can a bass player be? Anyway, at least I'm not a drummer.

And yes, I've been thinking about doing a full-scale model of a J bass and flying it.

Today, I saw a bass that, were I to attach some fins and a couple K motors, you could launch. The guy who owned it seemed to think that would be a good use for it, especially if you neglect a recovery system. It seems the truss rod is really screwed up, and it's not worth putting a new neck on.

Believe it or not, this just gave me an idea for something rocketry related. I wonder if it would work....

Zooty

As a physics major, I see a reluctance in many students to accept relative time when they take their first Special Relativity course. Relative time is counter-intuitive and conflicts with our experiences in the Newtonian reality we perceive. Our perceptions do not dictate the operation of the Universe, however.

Consider that we can, and do, measure time dilation and even use it in designing particle accelerators and maintaining the accuracy of the GPS system (which is just a satellite timing signal network).

Think about the experiment with identical atomic clocks. The set of clocks maintain very precise timing synchronization when stationary in the lab. Put one on a jet and fly it around at a relatively high speed compared to the others, and it is seen to be running behind the stationary clocks when it is returned. It is slower by a small, but easily measured amount.

What happened to the moving clock? In a phrase, it traveled backwards in time compared to the stationary clocks. Or, as is usually said, time slowed for the clock while it was moving relative to the stationary ones. But the end result is the same; the moving clock is out of time sync with the "stationary" reference frame. Same reason the GPS satellite signal timing incorporates relativistic corrections; the satellites are moving relative to the Earth's surface and their time is not the same as ours.

Carried to the extreme, you get the Twins Paradox; one twin embarks on a high speed rocket journey and comes back to find his brother on Earth many years older than he.

The fact is, time is relative to the motion of the reference frame of the observer compared to the reference frame of the event observed. What you see and experience is not the same series of events that a moving observer might experience or measure. If you were diving into a Black Hole, you would die pretty quickly. What we on Earth would see is a different matter having absolutely nothing to do with how fast the light from the black hole takes to get here; your velocity is "slowing" your time down as compared to us on Earth. Think about someone observing your fall from a nearby rocket.

Given that sub-lightspeed time is not an absolute and that working equations exist which describe it's behavior, assumptions on trans-lightspeed effects can be postulated based upon those equations.

In a very simplistic analysis (ignoring imaginary components of complex roots), one effect of greater-than c velocities is a sign change in the time variable (or term) in certain equations; the time term simply becomes negative. What does that mean? Reverse time? Who knows? Of course, these Special Relativity equations also "blow up" (usually from division by zero or infinite integrals) at a velocity = c, so speculation as to the meaning of (-t) is just that in Special Relativity, speculation. Other theories don't have such severe math problems, but they must also agree with Spec/Gen Relativity at some point and c is a limit (assumption) in both Special and General Relativity. Why, then, consider FTL and time travel at all? Quantum probability may allow a particle to "tunnel" past c (exist on the other side of the wave equation energy well) without actually attaining c exactly. Literally, skip over infinitely high energy requirements. We haven't "seen" particles tunneling past c yet, but its a very low odds possibility and the same tunneling effect is utilized in other real world objects and processes.

Your resistance to the concept of time travel is understandable, but your reasoning and examples do not correspond with known science.

In fact, I don't think velocity is the key to time travel, either. I think anti-matter is traveling backwards in time. ;)