No Time Travel, Sorry

MOBE2001 writes "The bad news is that time does not change. Spatial velocity is given as dx/dt. Velocity in time(dt/dt) is nonsensical. As simple as that. In other words, no time travel to the past or the future, no motion in space-time, no wormholes and no hanky-panky with your great, great grandmother. There is only the changing present, aka the NOW. The good news is that distance is an illusion and we'll be able to travel instantly from anywhere to anywhere."

Of course time travel is possible!

How else could people post articles in The Mysterious Future?

Re:Of course time travel is possible!

Trivially, as when a politician vows to curb inflation, buys a dog, names it "Inflation", and curbs it daily.
Read that in Mad Magazine about 20 years ago.
Only change: Alfred E. Neuman has been elected. Twice.

When I want to go forward or backward in Time...

I just flip the page. Same with Newsweek.

Re:Of course time travel is possible!

Why is motion in spacetime impossible? It has to do with the definitions of space and time and the equation of velocity v = dx/dt. What the equation is saying is that, if an object moves over any distance d x, there is an elapsed time d t. Since time is defined in physics as a parameter for denoting change (evolution), the equation for velocity along the time axis must be given as v = dt/dt which is self-referential. The self-reference comes from having to divide dt by itself. dt/dt always equals 1 because the units cancel out. This is of course meaningless as far as velocity is concerned.

Does the impossibility of motion in spacetime invalidate Einstein's relativity? The answer depends on whether one takes spacetime to be physically existent (as relativists do) or as an abstract, non-existent, mathematical construct for the historical mapping of measured events. If one chooses the former, one is obviously a crackpot or a fraud, or both. If one chooses the latter, then general relativity is to be seen as a mere math trick: the physical mechanism of gravity is still out there and it is incumbent upon physicists to find it.

This guy seems like an idiot to me. If you make the step to say that this is a mathematical construct that best describes our limited understanding of reality, which I believe to be true, you'll never be able to describe OR refute a more complete understanding of reality using that construct. You often need to discard and rethink the original concept or adapt it for it to improve. None of our knowledge, scientific or otherwise, is fully and completely right. Not one bit, it's just the best abstract model we've got. Everything we know will eventually be demonstrated to be incomplete, inconsistent or wrong. Which means you can't use any existing models to refute a new one. You can use them as a guide, you can say that the old and the new are inconsistent, but to refute them you need to go to the real world.

Re:Of course time travel is possible!

I didn't want to say I'll have told you so...

Drinking to much funny-juice

Nothing Can Move in Spacetime! By Definition!

That's weird because I could have sworn when I went to bed last night it was yesterday and now its today.

Nevertheless...this is fun. Looking at the equation from which all his arguments flow, it seems he is only demonstrating that it doesn't make sense to talk about one's velocity through time. I would agree. If I hop in my time machine and zip off to tomorrow, it doesn't make much sense for you to ask how long it took to get there. Or if you and I both have time machines and we decided to race to 1:00 pm tomorrow it would be always be a tie. But this is a far stretch from demonstrating that it is impossible. By this same logic we could define slope as the change in x over y or s = dx/dy. Does this definition make it impossible to move along the y axis because then the slope of our movement would be dy/dy? No. but it does say that if you move along the y axis your slope will be a constant.

Re:Drinking to much funny-juice

"That's weird because I could have sworn when I went to bed last night it was yesterday and now its today."

Not really. Now it's now, and that's all that is. You remember yesterday, but that is a memory occuring now. The past doesn't physically exist. Nor does the future. The only real (i.e. existing physically) part of our time perception is now.

Re:Drinking to much funny-juice

Not really. Now it's now, and that's all that is. You remember yesterday, but that is a memory occuring now. The past doesn't physically exist. Nor does the future. The only real (i.e. existing physically) part of our time perception is now.

Dark Helmet: What the hell am I looking at? When does this happen in the movie?
Colonel Sandurz: Now. You're looking at now sir. Everything that happens now, is happening now.
Dark Helmet: What happened to then?
Colonel Sandurz: We passed then.
Dark Helmet: When?
Colonel Sandurz: Just now. We're at now, now.
Dark Helmet: Go back to then!
Colonel Sandurz: When?
Dark Helmet: Now.
Colonel Sandurz: Now?
Dark Helmet: Now!
Colonel Sandurz: I can't.
Dark Helmet: Why?
Colonel Sandurz: We missed it.
Dark Helmet: When?
Colonel Sandurz: Just now.
Dark Helmet: When will then be now?
Colonel Sandurz: Soon.

Re:Drinking to much funny-juice

*golf clap*

Re:Drinking to much funny-juice

Airplane II: "This isn't the past or the present, Elaine! This is the future!"

Re:Drinking to much funny-juice

I picked a hell of a discussion to stop taking acid.

Re:Drinking to much funny-juice

Stop quoting me, bastard!

Re:Drinking to much funny-juice

Of course they left that out, as flux capacitors never work reliably and DeLorean's are almost impossible to find now days.

Re:Drinking to much funny-juice

it doesn't make sense to talk about one's velocity through time

All well and good, except that we've already proved in practice [metaresearch.org] that time has a different rate of passage for different people. Quote: "For GPS satellites, General Relativity predicts that the atomic clocks at GPS orbital altitudes will tick faster by about 45,900 ns/day because they are in a weaker gravitational field than atomic clocks on Earth's surface. Special Relativity predicts that atomic clocks moving at GPS orbital speeds will tick slower by about 7,200 ns/day than stationary ground clocks."

The difference is about 38,000 ns/day. Since the speed of light is about one foot per ns, if relativity were wrong (because time passed at the same rate for everyone), GPS would accumulate an error of about 7 miles per day. Such an error would be blindingly obvious to everyone using the system, and wouldn't require any fancy equipment to measure.

I'm interested to hear Mr Savain give an alternate explanation for how GPS works.

Er am i the only one to notice that...

time dilation [wikipedia.org] can be reproducably created, and in fact occurs on a daily basis, to a slight extent every time someone flies an airplane, or is launched into orbit aboard a space vehicle. technically just 'walking' will create a small bit of 'time dilation' it might be impossibly small to try and detect, or course.

Nasa has done a lot of research on this. if you accelerate a physical object to the 'speed of light' it's 'relative' time stops in comparison to that of the universe, while time continues to flow for the rest of the universe, until that object is decelerated to normal velocity.

So if 'time' can't be traveled through, then what exactly is 'time dilation?' Also, black holes are only useful for traveling 'forward' in time, the 'intense gravity' within a black hole 'simulates' traveling forward at the speed of light, the closer you are the greater the gravity, and thus the greater the time dilation. no one has formulated or demonstrated the possibly to go 'to the past' although if 'gravity' and 'light speed travel' can decelerate ones own flow of time so the future can be reached, then 'anti-gravity' or some form of 'reverse momentum' might perhaps allow one to experience a pocket of time where as one progresses through it the entire universe grows 'younger' the problem with this is gravity and acceleration seem to both follow temeperature and have a common starting point or 'absolute zero' below which it is impossible to go.

appologies to all the great science fiction, but traveling back in time just isn't possible.* (unless of course one travels forward through time throught the end of the universe as we know it, until a new universe is created from the ashes of the old one, assuming that that Does in fact happen, and given the nature of atomic mass to develop in a consistant patter, one travels to the 'future' of a new 'third world inhabited by the evolutionary decendants of apes' before they manage to create time travel, and knowing exactly how the universe unfolds (because of a massive quantum computer and impressive algrythm that can determine the exact course of events Before they happen, again, based on the data it recieved while you were traveling 'forward' in time...) and thus influence the development of a primative world that the locals call 'earth' because everything formed along the same 'predestined' pattern based on the arrangment of molecules in the universe when it collapsed... only you went and went Forward in time, causing the end of the universe to happen differently than when it ended last time, so now you're ona world inhabited by 27 foot tall sentient lizards who think mamals are a tasty snack.

oops. well, you shouldn't have tried to avoid the big crunch to see how the universe would unfold the next time around ;)

Idiotic

The guy who wrote the article simply does not understand the question that is being debated by the likes of Feynman et. al.

Everyone agrees that practical time travel is at the very least exceptionally unlikely. But whether our model of the universe excludes the posibility of time travel is another matter entirely.

Note that even if our model of the universe allows for time travel it does not mean that time travel is possible. Not least because we know that our model of the universe cannot possibly be completely right. Quantum physics provides an excelent model of the universe at a large scale, relativity provides a good model at the cosmological scale. The problem is that the two models are incompatible. At leas one of our models must be wrong. Most likely they are both approximations.

The other issue that the writer does not seem to grasp is that the ability for matter to travel through time and the ability of information to travel through time are very different issues. For meaningful time travel it has to be possible for information to move backwards in time and not just matter. Otherwise what would come out the other end would be a random soup of quantum particles, not the time traveller. This is the problem with black hole time travel, the most that can come out the other side is a random soup.

The 'proof' provided by the author only demonstrates that he does not have the slightest understanding of the subject he is pontificating on. dt/dt = 0??? No, all that shows is that the dimensions of the two quantities are the same. Besides x/x = 1 in most algebras.

Re:Idiotic

This reminds me of the great crackpot index [ucr.edu].

This dude's score is off the charts. I highlighted some of the good ones:

        1 point for every statement that is widely agreed on to be false.

        2 points for every statement that is clearly vacuous.

        3 points for every statement that is logically inconsistent.

      10 points for each favorable comparison of yourself to Einstein, or claim that special or general relativity are fundamentally misguided (without good evidence).

      10 points for claiming that your work is on the cutting edge of a "paradigm shift".

      30 points for suggesting that a famous figure secretly disbelieved in a theory which he or she publicly supported. (E.g., that Feynman was a closet opponent of special relativity, as deduced by reading between the lines in his freshman physics textbooks.)

      30 points for suggesting that Einstein, in his later years, was groping his way towards the ideas you now advocate.

      40 points for claiming that the "scientific establishment" is engaged in a "conspiracy" to prevent your work from gaining its well-deserved fame, or suchlike.

      40 points for claiming that when your theory is finally appreciated, present-day science will be seen for the sham it truly is. (30 more points for fantasizing about show trials in which scientists who mocked your theories will be forced to recant.)

casuality is the key

If "time travel" just means the usual physics definition of "tracing a trajectory backward" then of course you can regard it as happening all the time. Positrons (anti-electrons) can easily be regarded as electrons traveling "backwards" in time, so that a positron-electron annihilation event is nothing more than an electron traveling "forward" in time, then reversing itself and traveling "backward" in time. Obviously we (traveling steadily forward in time) see two particles with opposite properties converge and disappear. Whoopee.

However, I think what most people mean by "time travel" is something different, a causality loop. That is, they mean you do something (which they call "time travel") and this something lets you become your own grandpa, or influence the outcome of the Civil War, and so forth. Since, of course, those things influence the you that's influencing them (otherwise the story is not interesting), this makes a nice little loop of cause and effect: you influence x which influences you who influences x, and around and around.

Whether or not the physics of the universe allows such a thing, I can't see any obvious reason why it would cause big problems -- or even be interesting. Certainly it could not manifest itself the way it's shown in the movies, in which you see the loop first one way (Marty McFly's parents marry and produce him), and then another way (Marty's parents fail to marry, because McFly travels back in time and interferes with their meeting). That's logically impossible. If the loop exists at all, it must have one unchanging form.

That is, if Marty McFly does go "back in time" he obviously can't (or rather doesn't) prevent his parents from marrying and having him, because they actually did. Whatever he does "back in time" is already part of history. His "changes" already exist, and have always existed. Indeed, they can't even logically be regarded as "changes" because nothing really changed. Although...it's possible McFly, with his imperfect knowledge of the past, could have assumed something about the past was different than it actually was (e.g. he thought his parents met at the dance, instead of afterward, when some strangely-dressed clown introduced them). Therefore, when he "changes" history (by interfering with his parents meeting during the dance, and then "fixing" things up by introducing them afterward), he might be under the illusion that he is really "changing" history instead of simply causing it to happen as it actually did.

I suppose we could now argue about whether Marty's sense of free will (as well as our own) is therefore just a big fat self-delusion, but, ugh, not before a pint or two.

Re:casuality is the key

And what if these events occur, but aren't time travel at all? For the sake of the argument, assume you have the powers of a god, and sit outside the universe. As it plays out, you take a snapshot of the universe as it is in 1955. You save this. You let it play forward til 1985... then, you pause the VCR.

You do your little god thing, rearranging everything in the universe as it should be according to your snapshot, with a few exceptions... Marty and the Delorean. He didn't travel back in time, though, to him it can look like nothing else. But by the metatime clock that you the god uses, time has rolled on as it always has, only the universe was partially reset once or twice. I like this interpretation better, because you don't have to play mindfuck games with it.

Re:casuality is the key

Just a thought exercise. I dislike having to always regurgitate everyone else's ideas, like to think of my own sometime, even if they are pretty dumb.

I'm not sure conversation of energy is my first worry though, not in the strictest sense. Mass worries me more. Does the god fill in the missing particles that was Marty with something that won't be missed from some far corner of the universe? Now, I know that mass and energy are convertible to each other, especially in something as outlandish as all of this, so it's kind of a nitpick on my part. I wonder just how much energy (besides the mass of Marty/Delorean) would be needed to roll the clock back 30 years, if it's calculable.

The real killer is probably information entropy though. The "snapshot" itself isn't allowed, even if you postulate a god sitting in a metaverse/metatime playing with the Universe on his VCR.

Re: Really? A tie?

You're wrong. For the guy who travelled at the speed close to C time did slow down. Let's say that at the onset of the journey both planted a bonsai tree that grows at 1 inch per month. Upon the reunion, the earthbound astronaut's plant would be 12 inches tall while the traveller's plant would be only 1 inch high.

Re: Really? A tie?

No. You misunderstand the twin paradox: the twin that journeys will age less than the twin that stays behind in the classic "paradox".

The two frames are not inertial frames since one twin accelerates during the experiment. While the result is no doubt peculiar, there actually is no paradox to resolve.

You can read all about it here:
http://en.wikipedia.org/wiki/Twin_paradox

Re: Really? A tie?

Einstein's theory of general relativity tells us that to you he will have aged 24 hours, but to him you will have aged 24 hours

No, it doesn't.

_Special_Relativity_ says that two observers moving past each other in unaccelerated reference frames will each perceive that the other's clocks are running more slowly. The observations are consistent. To get the two observers into the same reference frame, one or both of them would have to accelerate, and general relativity conveniently works it so that the paradox vanishes.

In the actual example, one observer is remaining stationary, while the other is accellerating to high velocity, then accelerating to change velocity ("around the solar system") and then presumably accelerating a third time to return to the original reference frame. All three accellerations, plus travelling at high velocity relative to the rest frame, will cause the traveller's clock to run more slowly, as observed by someone in the rest frame.

Crackpottery, Indeed

Yes, yes, but where do Einstein, Jesus, Socrates and the Clinton's [timecube.com] live in this theory?

(Seriously. It's like he read Zeno's Paradoxes and it blew his mind, man.)

I'm no physicist

But in all my readings, I have learned one thing about physics. Nothing is "as simple as that".

But I time travel every day!

One second per second, so that dt/dt = 1.

--dave

The e-mail I sent to the editor was ignored.

This guy is a pseudo-scientific moonbat. Please don't waste your time with the not-so-FA.

Re:The e-mail I sent to the editor was ignored.

Note the URLs of the articles linked:

http://www.rebelscience.org/Crackpots/notorious.htm
http://www.rebelscience.org/Crackpots/nasty.htm#Spa ce

(emphasis mine.) That alone should make it pretty clear that this isn't meant to be taken seriously. Oh yeah, and the story got the "foot" icon, too, so even Taco got it. :)

Well obviously!

... because we already know everything there is to know about the universe

Or, as Ford Prefect put it...

As Ford Prefect put it, "Time is an illusion, lunchtime doubly so."

Method of Travel?

Do they use the Back to the Future method or the Bill and Teds method of time travel?

Also, did they attempt to spin the Earth backwards on its axis? I heard that works if there is a lady in distress.

Re:Method of Travel?

You forgot, "Slingshot the starship around the sun."

That works well when aliens try to talk to whales.

Let's play: spot the Loony

Um, no.

I'm sorry, but if you're going to put up a web page in which you call all the foremost theoretical physicsts in the world frauds, then you'd better have more evidence than some undergraduate-level pseudo-calculus and verbal smoke screens.

The t-axis or time-axis velocity component is 1, a dimensionless number. Now there are relativists who will insist that it is perfectly acceptable to express velocity in time with a dimensionless number but the rest of us with our head on our shoulders, know that it is not true. We know that a dimensionless number such as 1 has absolutely no meaning in as far as expressing velocity.
Not true. Normalized velocities are perfectly reasonable things to express. Mach 1.25 is a perfectly well-defined speed that does not violate any laws of physics, and what do you know--it's a dimensionless number.

I'm sorry, but this page is really quite embarassing for the author's parents and any physics teacher's they've ever had. This sort of reminds me of people that read things like A Brief History of Time, a perfectly excellent book, and then try to tell me that the physics is really great and it would be so much better unencumbered by the mathematics.

I don't think real time travel, a-la Dr. Who is physically possible. But the "arguments" on this web page don't really make sense, much less prove all those physics wrong.

Craig Steffen
Ph.D. Physics, Indiana Unversity, 2001

Re:Let's play: spot the Loony

Ph.D. Physics, Indiana Unversity, 2001

And this guy should know what he's talking about-- somehow he's managed to make his post travel 5 years into the future.

Re:Let's play: spot the Loony

You are wrong.

Mach is the ratio of two speeds. Doing such produces a number in which the units cancel out. Speed/Speed = dimensionless. This also brings up another property of a dimensionless number, in that the value *does not change* in any unit of measurement. Mach 1.5 is the same in SI, FPS, or any other system.

Don't believe me? Here [wikipedia.org]. "As it is defined as a ratio of two speeds, it is a dimensionless number." I'd hate to think you believe what you said... as others are taking you seriously.

Please don't respond back... I don't want to debate this further and you are most utterly wrong. I hope you don't work on... anything.

Ha!

distance is an illusion and we'll be able to travel instantly from anywhere to anywhere.

HA! Take this from a person who has been in a long distance relationship... The distance is a reality, the relationship is the illusion.

We really outa get these theoretical scientist types out of a lab for a beer.

I must complain

That's it. I'm going to write a letter of complaint to Michael J. Fox and Christopher Lloyd to express my disgust at being deceived for the past 20 years.

All you need for time travel is...

A Deloreon, a flux capacitor, 1.21 gigawatts of power, and enough road to get up to 88 miles per hour.

Re:All you need for time travel is...

Roads? Where we're going, we don't need roads.

To the future

Going forward is easy. The hard part is not dying.

I desperately want to mod the story...

-1, Nutjob

Actually, ...

I'm from the year 3042. We have found that time travel is real, and would have discovered the time machine in 2048, but scientists were detered by this article.
Dan Church is Wicked Ill [danchurch.tk]

Re:Actually, ...

Uh...yeah...but I'm from the year 802701 (AD) and we planted that article in 2006 to delay you folks in 3042 from discovering temporal warp and then running into the hidious and irresistable...well...you'll find out.

Textbook strawman arguments.

Spatial velocity is given as dx/dt. Velocity in time(dt/dt) is nonsensical.

That would be a lovely argument if changes in position were measured in velocity.

You describe spacial travel as the dx, not the dx/dt. It stands to reason that you would describe time travel with the dt, not as some rate of travel we haven't come up with yet.

Closet time travel

Go into your closet, and bring enough food and water for 5 years.
Now wait...and eat sometimes.
5 years later, exit the closet.
You will find that time of the world has advanced from when last remembered by 5 years.

PS. don't forget to setup an auto-pay for your residential rent/payment. Otherwise your travel may be interrupted, and you will not be able to travel the full 5 years.

Not nearly as cool as timecube...

This guy is good, but he's not nearly as entertaining or mind-warping as the TimeCube [timecube.com] guy. Four days in one!!!

CmdrTaco has been scammed by Usenet schizo

Dear Rob

I'm sorry to have to tell you but you've been scammed by a well-known internet kook called Louis Savain into slashdotting his junk

If you google for "nothing moves in spacetime" and "rebelscience.org" you'll find lots of references to this particular paranoid schizophrenic (no, I'm not kidding)

He likes to spam sci.physics and sci.physics.relativity with his junk. One of his recent postings [google.co.uk] is fairly typical:

On Sun, 22 Jan 2006 16:59:17 +0000 (UTC),
glhan [e-mail] (Gregory L. Hansen) wrote:
>In article ,
>Traveler wrote:
>>On 22 Jan 2006 07:55:33 -0800, glhan [e-mail] wrote:

>>Repeat after me: NOTHING MOVES IN SPACETIME.

>World lines don't move in spacetime. When people talk about the motion of
>a particle they refer to a succession of points on the worldline, not the
>worldline in its entirety.

Repeat after me: ABSOLUTELY NOTHING MOVES IN SPACETIME!
NOTTHIINGGG!!!!

What this means is that there is NO CHANGE in spacetime (that's why it
was called Einstein's block universe by Karl Popper) and spacetime is
a fictitious math construct with no counterpart in reality. Now, isn't
it a tad weird that your idol Einstein agreed with his friend Kurt
"lunatic" Godel when he announced in 1949 that the spacetime of GR
allows time travel to the past via time-like loops?

Now hold on a southern cotton picking second! Aren't Kurt Godel and
Albert Einstein revered by physicists as two of the smartest men that
ever lived? Yep. ahahaha... One then wonders how they can be so stupid
as to believe in motion in spacetime. ahahaha...

http://www./ [www.] rebelscience.org/Crackpots/notorious.htm#Einstein

ahahaha...
>>> Or that your alien-induced lattice that exists nowhere is
>>>also an abstract model of your invention?

>>Nope. My lattice is not made of abstract crap but of real particles.
>>You crackpots call them virtual photons. ahahaha...

>You have a model that describes a lattice that is not made of abstract
>crap. You're like the screen writer who writes a line like "This isn't a
>movie, you know."

Maybe in your imagination but I know one thing: I am not an ass
kisser. I do my own thinking, than you very much. ahahaha... And
that's the way I like it. ahahaha... AHAHAHA... ahahaha...

Physics is so much phucking phun! ahahaha...

Louis Savain
Why Software Is Bad and What We Can Do to Fix It:
http://www.rebelscience.org/Cosas/Reliability.htm [rebelscience.org]

I would suggest you remove the story

Re:SG1 Answers!

I did what?

Re:SG1 Answers!

Time travel, remember? YOu haven't done it yet.

Re:Slashdot allows any bullshit site now?

Then again, maybe I should just "laugh, it's funny"...