it is always pathetically hilarious every time you drop this hypocritical line.
Time Travel is Science Fiction
- Thread starter Farsight
- Start date
In general time travel into the past, seems to create many more problems and apparent possible paradoxes then future time travel.
That is fairly easy to see, and I'm sure you really do see it.
It has also been pointed out in all the links I have given from Sagan and Thorne.
Now please show me where I have ever said that time travel into the past is impossible.
I havn't and neither have any of my links.
Please show me how anyone can even attempt to infer I said time travel into the past was impossible.....
I said from your pasted quote of mine...........
"The over riding fact on this subject is that the laws of physics and GR in no way forbid the possibility of time travel.
And any sufficiently advanced civilisation could achieve it, even our own.
Both are undeniable facts accepted by all mainstream common sense logical physicists."
You then said..........
I noted:
now you seem to agree time travel into the non-existing past is impossible but think time travel into the non-existing future is permitted by the laws of physics. I don't know where there is any mention of different laws of physic for the past than for the future - how can you have it "both different ways"?
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Probably closer to a dozen times. But so has everyone in this thread. It is all continually going over old ground, and the fact as detailed in my previous post here, that confusion/misinterpretion seems rife, I see it as essential to keep mentioning it, as it seems to be getting lost in the other philosophical and pedant posed by our naysayers, particularly Farsight and his speudoscience take on things in general.
tashja
Registered Senior Member
Good work as usual tashja, and nice to hear another professional.
It should be noted that he said.....
There is an important difference between time dilation and time travel. What fast moving muons experience is time dilation, where the clock of an object moving relative to an observer appears to run more slowly than a clock stationary with respect to the observer. This a consequence of Special Relativity.
I cannot accept that view and I see it as opposite to what Sagan and Thorne have claimed.
eg: If I travelled at 99.999% "c" and returned to Earth 12 months later, by my onboard ship's clocks, both biological and mechanical, I will be returning to an earth 230 years down the track. This is time travel in any one's language, and is the opnion of Thorne, and Sagan as well as Carroll and Smolin.
He then said......
If I were talking about time travel in the sense of Doctor Who or The Time Machine then I would expect the time traveller would take a path through space and time not permitted by the rules of Einstein’s theories of relativity that have been tested by experiment."" In this sense the muons aren’t time travellers"""
NOTE: IN THIS SENSE.....so in the other sense, it can be construed as time travel???
I'm sure it could.
And then we have this doozy that completely refutes what delusional Farsight claims....
There are some situations where time travel remains hypothetically possible while obeying the rules of these theories, and some discussion about what travelling backwards in time might mean, but no experimental evidence for time travel in this sense. Stephen Hawking’s whimsical ‘proof’ that it isn’t possible is that we don’t meet tourists from the future, but this isn’t meant to be an absolute proof.
So in essence the good professor has refuted Farsight's claims, while remaining part non commital on the other stuff.
But Farsight sees it as agreeing with him....
Maybe too much of themight be at fault.
Dr. Baker:
I wonder if the question here is what constitutes time travel. We all travel forwards through time – this year I’m a year older than I was last year. Travelling through space at different speeds means that we all travel into the future at different rates, though for most of us those differences are utterly miniscule. The most any human has managed to age slower than the rest of us has been about 20 milliseconds, due to time dilation. I think that being a proper time traveller though is rather different from that – you need to be able to move in both directions. Otherwise ‘Back to the Future’ would just be ‘To the Future’ and ‘The Time Machine’ would be ‘The machine we later found had sent a man into the future’, which don’t have the same ring to them and couldn’t sustain their plots.
The story quoted and attributed to Sagan and Thorne is generally called the twin paradox, though it pre-dates them to 1911. Two twins are on Earth and one gets in a spaceship that travels for a certain time at very high speed and then comes home to find that the other twin is much older. That is to say that much more time has elapsed for the twin who stayed fixed on Earth. It is explained in detail at: http://en.wikipedia.org/wiki/Twin_paradox. They have both moved into the future at different rates just like the rest of us do, only by a more spectacular margin. No moving of anyone backwards in time.
Getting back to the past is altogether more difficult to explain in terms of the existing understanding of physical reality. While quantum mechanics and relativity are written down in ways that don’t mind whether they operate forwards or backwards in time, that may be because we’re not very good at writing down theories that have a preferred direction in time, or the universe doesn’t have a preferred direction of time. What we do know really prefers one direction in time is the second law of thermodynamics. Kip Thorne points out on the page that was linked to in post #832 that most of the ways you could think of making a time machine based on quantum mechanics and relativity fall down when they meet the second law of thermodynamics and the ones that might not fail for other reasons. From what we know about time at the moment there’s only one direction we can go through it, unlike space.
Ultimately science can’t say that things are impossible, only that no way of their happening is consistent with our current state of knowledge. That it is how I’d describe time travel into the past right now. Kip Thorne’s description seems to suggest that he and Stephen Hawking seem to know no way of time travelling at the moment. I’m sure they’ll still work hard at improving the current state of knowledge about how relativity and quantum mechanics relate to each other, and if something pops up that would allow a time machine then you can be pretty certain they’ll mention it.
Hope that helps,
Peter
Dr. Paul Lebrun:
No! The muon isn't special. We currently have no real understanding why we live a world with three families of leptons (the electrons, muon and tau). As far as we can tell, they all behave the same way, following the laws of causal Quantum Electrodynamics. Causal being the key word.
Paul
Read this wiki starting at "In modern physics, the notion of causality had to be clarified". Experimental attempts associated with the concept of time travel are trying to send information faster than the speed of light.A whole bunch of physicists that are professionally qualified, which you are not, all happen to disagree with you.
Remember, as much as it literally rips out the foundation stones of your delusional take on accepted cosmology, TIME TRAVEL IS NOT FORBIDDEN BY THE LAWS OF PHYSICS AND GR.
You see, [and I'm really trying to help you here] your whole take on cosmology is built like a house of cards...It just takes one obvious error/misinterpretation or woo aspect, and your whole structure of cards come tumbling down.
Now that you have been told the truth, you can put me back on ignore.
http://en.m.wikipedia.org/wiki/Causality_(physics)
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I didn't like that response, tashja. It's as if it was written for popscience groupies with no physics knowledge whatsoever. I'm going to give some comments:
We all travel forwards through time – this year I’m a year older than I was last year.
Travelling through time is just a figure of speech. Time is a cumulative measure of some regular cyclical local motion, it just isn't something that we travel through.
Travelling through space at different speeds means that we all travel into the future at different rates,
No it doesn't. Our macroscopic motion through space plus our microscopic internal motion cannot exceed c. So when we move fast through space our internal motion is reduced, so we suffer time dilation. There is no way you can travel into my future such that you're living in the middle of next week.
Again though for most of us those differences are utterly miniscule. The most any human has managed to age slower than the rest of us has been about 20 milliseconds, due to time dilation.
No problem with that.
I think that being a proper time traveller though is rather different from that – you need to be able to move in both directions. Otherwise ‘Back to the Future’ would just be ‘To the Future’ and ‘The Time Machine’ would be ‘The machine we later found had sent a man into the future’, which don’t have the same ring to them and couldn’t sustain their plots.
You can't travel backwards in time because you can't even travel forwards in time.
The story quoted and attributed to Sagan and Thorne is generally called the twin paradox, though it pre-dates them to 1911. Two twins are on Earth and one gets in a spaceship that travels for a certain time at very high speed and then comes home to find that the other twin is much older. That is to say that much more time has elapsed for the twin who stayed fixed on Earth. It is explained in detail at: http://en.wikipedia.org/wiki/Twin_paradox.
That's fair enough.
They have both moved into the future at different rates just like the rest of us do, only by a more spectacular margin. No moving of anyone backwards in time.
They haven't "moved into the future". The travelling twin has experience less local motion, that's all. There's no moving of anyone backwards in time, and there's no moving of anyone forward in time either.
Getting back to the past is altogether more difficult to explain in terms of the existing understanding of physical reality. While quantum mechanics and relativity are written down in ways that don’t mind whether they operate forwards or backwards in time, that may be because we’re not very good at writing down theories that have a preferred direction in time, or the universe doesn’t have a preferred direction of time. What we do know really prefers one direction in time is the second law of thermodynamics. Kip Thorne points out on the page that was linked to in post #832 that most of the ways you could think of making a time machine based on quantum mechanics and relativity fall down when they meet the second law of thermodynamics and the ones that might not fail for other reasons. From what we know about time at the moment there’s only one direction we can go through it, unlike space.
We don't go in any direction through time. You can't point in this direction because it doesn't exist. But space exists, and things exist, and light, and all these things move in all directions through space. That's the reality, the rest is abstraction.
Ultimately science can’t say that things are impossible, only that no way of their happening is consistent with our current state of knowledge. That it is how I’d describe time travel into the past right now. Kip Thorne’s description seems to suggest that he and Stephen Hawking seem to know no way of time travelling at the moment. I’m sure they’ll still work hard at improving the current state of knowledge about how relativity and quantum mechanics relate to each other, and if something pops up that would allow a time machine then you can be pretty certain they’ll mention it.
Science can say that things are impossible when they are based on misunderstanding and fantasy. The past is merely a label we apply to the state of the universe when everything is where it used to be. There is no way we can move to make everything move back to where it was, such that it never moved at all.
We all travel forwards through time – this year I’m a year older than I was last year.
Travelling through time is just a figure of speech. Time is a cumulative measure of some regular cyclical local motion, it just isn't something that we travel through.
Travelling through space at different speeds means that we all travel into the future at different rates,
No it doesn't. Our macroscopic motion through space plus our microscopic internal motion cannot exceed c. So when we move fast through space our internal motion is reduced, so we suffer time dilation. There is no way you can travel into my future such that you're living in the middle of next week.
Again though for most of us those differences are utterly miniscule. The most any human has managed to age slower than the rest of us has been about 20 milliseconds, due to time dilation.
No problem with that.
I think that being a proper time traveller though is rather different from that – you need to be able to move in both directions. Otherwise ‘Back to the Future’ would just be ‘To the Future’ and ‘The Time Machine’ would be ‘The machine we later found had sent a man into the future’, which don’t have the same ring to them and couldn’t sustain their plots.
You can't travel backwards in time because you can't even travel forwards in time.
The story quoted and attributed to Sagan and Thorne is generally called the twin paradox, though it pre-dates them to 1911. Two twins are on Earth and one gets in a spaceship that travels for a certain time at very high speed and then comes home to find that the other twin is much older. That is to say that much more time has elapsed for the twin who stayed fixed on Earth. It is explained in detail at: http://en.wikipedia.org/wiki/Twin_paradox.
That's fair enough.
They have both moved into the future at different rates just like the rest of us do, only by a more spectacular margin. No moving of anyone backwards in time.
They haven't "moved into the future". The travelling twin has experience less local motion, that's all. There's no moving of anyone backwards in time, and there's no moving of anyone forward in time either.
Getting back to the past is altogether more difficult to explain in terms of the existing understanding of physical reality. While quantum mechanics and relativity are written down in ways that don’t mind whether they operate forwards or backwards in time, that may be because we’re not very good at writing down theories that have a preferred direction in time, or the universe doesn’t have a preferred direction of time. What we do know really prefers one direction in time is the second law of thermodynamics. Kip Thorne points out on the page that was linked to in post #832 that most of the ways you could think of making a time machine based on quantum mechanics and relativity fall down when they meet the second law of thermodynamics and the ones that might not fail for other reasons. From what we know about time at the moment there’s only one direction we can go through it, unlike space.
We don't go in any direction through time. You can't point in this direction because it doesn't exist. But space exists, and things exist, and light, and all these things move in all directions through space. That's the reality, the rest is abstraction.
Ultimately science can’t say that things are impossible, only that no way of their happening is consistent with our current state of knowledge. That it is how I’d describe time travel into the past right now. Kip Thorne’s description seems to suggest that he and Stephen Hawking seem to know no way of time travelling at the moment. I’m sure they’ll still work hard at improving the current state of knowledge about how relativity and quantum mechanics relate to each other, and if something pops up that would allow a time machine then you can be pretty certain they’ll mention it.
Science can say that things are impossible when they are based on misunderstanding and fantasy. The past is merely a label we apply to the state of the universe when everything is where it used to be. There is no way we can move to make everything move back to where it was, such that it never moved at all.
This is you adopting an absolute space and time that both Einstein and Minkowski rejected. What do you have to say about their explicit arguments against this position?
Not really, since it contradicts your position to say that more time has elapsed on one path between two events than on another path between those events. You believe that there is only one "time", never addressing the arguments of the scientists that you claim to be citing who disagree violently with your position.
Godel quite clearly gave an example model where many things moved to back where they were along with everything else. Despite citing a book about Godel, you seem completely ignorant of his work on this subject.
The travelling twin turns round and comes back so we say he's the one who was moving.
It doesn't contradict me at all. You surely must understand this by now? Each twin is equipped with a parallel-mirror light clock. The light path is straight up and down for the stay-at-home twin, and zigzag for the travelling twin. When they meet back up, they meet up at the same time regardless of their clock readings or grey hairs, and the light-path-lengths in their clocks are the same.
I'm not. But you are clearly ignorant of A World without Time: The Forgotten Legacy of Godel and Einstein.
Attachments
This has nothing to do with the arguments of Einstein and Minkowski that you are ignoring. It is another transparent attempt to avoid answering a direct question about your specific position.
Unlike you, I have actually read the relevant parts of that book. It has nothing to do with your arguments.
You are yet again using a link as a deceptive technique to avoid real answers.
Again, you made claims about crystals and about how one should really do physics that you have yet to support.
Of course, since you have admitted that your physics is not about actually learning anything about physical systems, this is not surprising.
Er no, I'm the guy who isn't ignoring Einstein and Minkowski and others. But since you have demonstrated your insincerity, I am ignoring you.
Reference please!
Saying each had a clock or even an ideal clock, OK. But saying that the twins had light clocks is like saying they have cesium clocks. It is an invention and assertion of your own.
Just ignoring what they really intended to say!.. Putting your own words and interpretations into their mouths, so to speak!
And here we have the standard Farsight approach: make some grand claims; avoid direct questions about those claims; when questioned in a way that is hard to avoid, claim that you're being insulted; throw some insults; add to ignore list.
That's fine. Farsight always ignored the important questions, since it is clear that he can't do physics and he's doing this for some other reason.
http://lofi.forum.physorg.com/A-Despairing-Open-Letter-From-A-Physics-Teacher_17140.html
It's sad that he has this fantasy physics that he clings to so he can imagine that he isn't failing his children, but it can't be healthy.
I don't think it is "time travel" any more than other means actually available* to some small extent now that slow one's rate of aging as measured by clocks on earth. Yes conceptually it is possible by accelerating for a few years at the few Gs max the body can tolerate for more than an hour, so you could in principle live to die 200 years by earth's clocks after your birth, but actually being the "traveling twin" to do that probable would cost more than a year of the world's total GDP, so will not be done, even if technically possible.... Well mainstream accepted opinion in general is saying it is time travel.....and more importantly, so do I.
TRAVELLING TWIN: [ on returning to Earth]How's Obama going? [to a white house security gaurd]
SECURITY GAURD: Are you OK matey? He died 200 years ago!
TRAVELLING TWIN: What years is this?
SECURITY GAURD: 2214, why?
TRAVELLING TWIN: But I have only been away for 12 months.
Yeah, it's time travel!
Much more probable of actually being done is learning the detail of how bears do hibernate for many months and some of that knowledge being applied to humans so they can live to see their great, great grand children and the nature of the world that will exist then. Or an application of that knowledge may be government financed to reduce the food and other cost of colonizing Mars, etc.
In both cases no one is Traveling into a future that does not yet exist. We all are Traveling into future as it becomes the present. But via space ships or suspended animation, one can live longer or "age more slowly" by Earth's clocks.
I have asked you before if you call suspended animation "time travel" - no reply yet, but I'll wait. There is no logical or rational reason I can see /understand why only one of these two methods of slowing the aging process should be called "time travel" and not the other. If you can tell me one, please do.
It is not that the laws of physics do not prohibit time travel (or dozen of the other concepts in science fiction) - it is the simple fact that there is no where to travel too as neither the future or the past exists ANYWHERE now. One once did and the other some day will be our "now." The laws of physics do not prohibit travel to the apex of a sphere. - What prohibits that is that there is nowhere an apex of a sphere to travel to.
* The drugs inducing coma and lowering whole body temperature as used mainly with brain and open heart replacement surgery, which takes most of a day to do.
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No it isn't. See the Simple inference of time dilation due to relative velocity:
Observer at rest measures time 2L/c.
Observer moving parallel relative to setup, measures longer path and thus, with same speed of light c, measures longer time 2D/c > 2L/c.
No it isn't. See the Simple inference of time dilation due to relative velocity:
Observer at rest measures time 2L/c.
Observer moving parallel relative to setup, measures longer path and thus, with same speed of light c, measures longer time 2D/c > 2L/c.
That is not a reference to anything real! it is once again an example of your illusions.
the link in your link would not open for me, but in your link I read this:
"Students should learn methods to mathematically describe the physical world rather than answer word questions that rely on opinion and non-scientific ideas."
I was reminded of the fact that the math of post 28 has been ignored in favor of opinion. It is a mathematical fact that the entire universe can be describe with no reference to time as shown in post 28. As I have more than half a dozen times admitted that "no need for time in physic" does not prove time does not exist. Only adding Newton's first rule of philosophical reasoning (now commonly call Ockhams's rule) can one say that time does not exist. (but it may as Ockham's rule is a suggestion, not a law.) Newton was quite clear that the "t" in his equations was NOT sensible, but some "absolute mathematical time" and recommended that what we now call sidereal time (his "astronomical time" an observable that can be sensed) be used as the best approximation.
As the teacher complained, we have nearly ~900 posts in this thread now telling opinions of just thinly disguised name calling, but no refutation of post 28 by means of mathematics.
No. Farsight's two drawings makes time dilation clear for most. A few words may help you understand. There are three events. First a brief laser flash leaves A and then hit perpendicularly the mirror at B and finally returns to A. - a in one statinaray frame. The lower drawing is how those three events are seen by the moving to the right observer. He to see the flash leave A hit the mirror B at an angle not 90 degrees, and return to A. via a longer path. Usually this is drawn with the lower part inverted. (A & C above B)
Just as these two drawings below explains why light bends in a gravity field:
Left (referred to in text as Fig 10.3A) is for the rocket accelerating "observer A".
This Fig 10.1:http://www.newtonphysics.on.ca/einstein/chapter10.html said:during the time interval Dt, light seems to travel a vertical distance Dh:
Therefore, as illustrated on figure 10.3A, for the accelerated observer, the beam of light will appear to follow a curve and will hit the opposite wall at a distance Dh below the entrance height.
Top left above the quote (for "observer A") is for the elevator accelerating up ("false gravity" inside). Observer B is in box on earth surface (in "true gravity.")
SUMMARY: Farsight's and the above drawing are amost impossible to not have been seen more than once by any one in a physic course concerned with the effects of gravity & effects of velocity near the speed of light. THEY ARE ABOUT AND MAKE CLEAR THE REAL WAY NATURE IS. Any different POV is just false opinion.http://www.newtonphysics.on.ca/einstein/chapter10.html said:
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