Time travel

[Baron von Richthofen]

:face:Who is interested in time travel, if you are have a look at this
http://www.brianbosak.com/

[Nesti]

Don't mean to be a wet blanket. I don’t believe in time travel, it doesn’t lend itself toward supporting a stable reality. Also, time travel would necessitate the abolition of freedom of choice, since time travel would require a purely deterministic universe. That’s why there’s an arrow of time, freedoms must be accounted for.

In my opinion, there is only one type of temporal travel for us, time dilation…I don’t support teleportation either…it’s all hype.


Cheers
Mark

[Bobbyoutback]

Iv'e had an interest in this subject for a long time , some great minds have said it's not impossible !

From memory the main difficulty regarding paradoxes is going back , I do remember a convincing argument about not being able to go further in the past then when the time machine was built .

Love to jump into tomorrow for obvious reasons ;)

[Esseth]

From what I understand, while it doesn’t break any of the laws of physics it bends them quite a bit and would require a huge leap forward in our understanding of the universe.

Basicly when we are sending space crafts to other systems and have things like effective anti-matter engines and have worked out the kinks in fussion power... then we might make some break throughs.

"About not being able to go further in the past then when the time machine was built" yeah I’ve heard that as well. however there are several different theories on the matter...read all about them in Physics of the Impossible.

[wavelandscott]

While I don't know all of the details, my Wife's Uncle who is a retired professor has a patent that supposedly makes time travel at least theoretically possible (as he self describes it).

The method is described but to my knowledge has not been built...

His Father (my Wife's Grandfather) was a patent attorney and as a "retirement" project completed the project.

James F. Woodward
Departments of History and Physics
California State University Fullerton

Theoretical consequences of the gravitational origin of inertial reaction forces, that is, Mach's principle, are explored. It is argued that Mach's principle leads to the conclusion that time, as we normally treat it in our common experience and physical theory, is not a part of fundamental reality; the past and future have a real, objective existence, as is already suggested by both special and general relativity theory. A laboratory scale experiment whereby Mach's principle, and thus radical timeless ness, can be established is mentioned.

I don't claim to understand it but it makes interesting cocktail conversation...

[avandonk]

If time travel was at all possible we would be inundated with tourists from the future.

Even if you could hypothetically 'travel' in time the spatial navigation would be a bit of a problem. Even if you maintained your initial inertial frame of reference.

Where exactly was the Earth ten years ago say or even ten seconds? What is your reference frame for spatial position?

The equator moves at about 1600 km/hour due to the Earths rotation. 0.5 km/sec
The Earth goes around the Sun. 30 km/sec
The Sun orbits the Galactic centre. 250 km/sec
Our galaxy is moving relative to other nearby galaxies. 300 km/sec
Our local group of galaxies are moving relative to others. ?>300 km/sec

And so on.....

Actually we are all time travelers as we are moving into the future at 1 sec/sec.

Bert

[Omaroo]

You'd think! :) ... unless they were cloaked... :lol:




I wonder what our actual linear velocity is on any chosen vector? I'd be some "carrier" landing to get back to, spinning like we do as a planet within a spinning solar system within a spinning galaxy within......

[Rod66]

Its simple. Whenever a time traveller passes through to our time , they create a new existence hence our future is not necessarily his future anymore. Of course getting back to his own future is problematic and some sort of dimensional marker may need to be created. This also avoids the grandfather paradox, he can kill as many of his ancestors as he likes, he won't disappear.

But it does make you wonder where are all these guys from the future???

Rod

[Astro78]

So we're all but certain the earth is effecting space time. hmm

We've got lasers to bend around matter now, thanks Havard Uni.

No laws of physics prevent time travel whatsoever, hmm.

hmm hmm and hmmm

[shane.mcneil]

I am in no way qualified to comment on this but personally I think that time travel is unlikely, and if it is possible, one would not be able to change past or future events. I've often wondered though if an extra dimensional life form would be able to see all of our time stretched out before them? Just as a 3D being would see a dimension that a 2D being couldn't.

Having said all that, I have read that these experiments might imply some passing of information back through time on the quantum level.

Here (http://en.wikipedia.org/wiki/Wheeler%27s_delayed_choice_experime nt) and here (http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser).

[Robh]

What is time? It is just the perception of one event followed by another; the ticking of numbers on a clock.
When an event has occurred here on Earth, an infinite number of events have simultaneously occurred throughout the Universe.
One cannot wind back this series of events. In fact, time itself is not absolute and its measure changes in varying gravitational fields.
To be able to recreate a whole Universe at a perceived point in time gone past is in the realms of pure fiction.
To be able to create a future Universe, which is a projection of every indeterminate event today, is even greater fantasy.

Regards, Rob.

[renormalised]

Yeah, but what if we perceive as being "reality" is nothing more than an illusion. Let's say that time doesn't really exist, but is a consequence of the way our consciousness interacts with this existence at a quantum level.

[sjastro]

Just to add to the general confusion, in particle physics time has a very definable characteristic.

In particle decay involving the weak force, time reversal is required for the process to proceed.

Steven

[Nesti]

Doesn't the pion decay occur instantaneously. In that the tunneling of the alpha particle, from within the strong force's expressed radius to outside the strong force's expressed radius, takes no time at all...the alpha particle then decays within the radius of its wavelength, radiating out as the weak force (radiation)?

Cheers
Mark

[Baron von Richthofen]

I suffer from precognition under certain conditions which I try to avoid like the plague and which has been witnessed by reputable people like police and teachers
I say suffer because I found that you can not change the event, the best you can do is postpone it for a few minutes, I don't want to know the future if I cant do anything about it.:(

[FredSnerd]

Thats what I was just about to say.

[Nesti]

snap!!!

[FredSnerd]

When I was a kid I'd think people who'd say stuff like anything is possible were just talking bunkum. But now as we're only just beginning to discover just how complex and vast the universe is I dont know that you can rule anything out, including time travel. We just simply dont know enough at this stage.

[sjastro]

Decay of the alpha particle does not involve the weak force hence time reversal doesn't occur. Beta decay does.

In particle physics, particle interactions occur if symmetry is invariant before and after the interaction.
Experimentally it has been found that parity (P) and charge conjugation symmetries (C) are not conserved in beta decay. Neither are the 2 symmetries together (CP). By introducing a time symmetry T, the combined symmetry CPT is invariant and the interaction proceeds.

A more technical description of this can be found at:

http://en.wikipedia.org/wiki/CPT_symmetry

Regards

Steven

[xelasnave]

I think folk can get carried away with hopes and dreams ..they hope time travel is a fact and so they lean that way....

Where do we get such notions I wonder...

and why ..as some scientific "news flashes" say.."black holes may hold the key to time travell"... what a long bow to draw when black holes still remain a matter we know very little about..and yet many read such "head lines" and away they go... I think many get their science from Hollywood when it comes to black holes.

Some folk seem to think if you can go faster than light that means you can beat time... why would this be so in any reality??? even if light travelled "instant" I can not see why or how such will have any effect upon time...and I do suspect the physics can lead us to find a mathmatical extrapolation to believe in such an idea but I feel such extrapolations lead us away from any reasonable reality.

Nature says time is merely a limit on "speed" at which a series of happening can occur and in this that suggests strongly it is a one way street.

alex

[renormalised]

Who said reality was reasonable...there are plenty of instances, and not just in science, that says otherwise.

[Robh]

Just because the human mind can conjure an idea does not mean it exists in reality. For example, I can conjure images and stories of ghosts and perhaps even believe in ghosts, but that does not mean ghosts exist.

Time just reflects the passing of events. Conceptually, I can imagine a retrace of some events back to a point in time passed by. However, it is not possible to recreate the infinity of events that have occurred across the Universe for the last second, let alone for the last decade or 100 years.

Rob

[bobson]

We can play it this way as well then :)

We use our scopes to collect light in order to see image of the object in the sky. Lets assume we are looking at the object that is 100 light years away from us. In other words it takes 100 light years for the light to get to us.
Now, lets assume we know something faster than light, twice as fast in fact. If we send that towards the mentioned object lets say 10 light years towards that object. Then record that object with it and send the image back to us again twice as fast as light.
We would be looking at the future of that object. In relevance to us of course, those things already happened as far as that object is concerned. So its a past for the object and future for us for that object.

See..its easy :)

bob

[FredSnerd]

Einstein wondered how an “apparently” simultaneous event, observed by 2 observers, one in motion and the other stationery, could appear to occur at different times. The answer. It was not the speed of light but the speed of time that changed. How crazy is that. Time does not move at the same pace AND even crazier; time does not move at the same pace for all of us at the “same time”. The answers that are waiting for us out there are down right weird. Einstein proved that. I just wouldn’t be in too much of a hurry to dismiss anything at this stage.

[renormalised]

The corollary of that is what we think is impossible doesn't mean it is, necessarily. We've hardly scratched the nature of what we perceive of as reality (that is a subjective perception, anyway). Yes, we can only go by what we know, but to then believe that what we know is close to the whole story is skating on very thin ice.

[Bobbyoutback]

Because Earth is not the best time keeper we now measure a second by the number of flicks of frequency wavelength of radiation emitted by atoms of cacsium (9,192,631,770 flicks a second ) .
But whats gets me is this " if you could measure a second near a black hole you would get the same number of flicks per second but those not near the black hole would find more time had passed , being near the black hole event horizon does effect the light of the oscillations of electromagnetic waves including the atoms we are made of .
As Einstein realized , light provides the only fundamental measure of both length & time in the universe .

If you have read this far I'm astounded :scared2:

Cheers Bobby.

[Astro78]

Alrighty that's a one argument :P



Well that's this thread covered ;)

[shane.mcneil]

Won't the answer depend on what time actually is? I thought time was just the rate of change in physical processes including biological. We've invented a method of measuring that change (hours, minutes, seconds etc) which we call time, but it is not a real thing. Time dilation occurs because as you approach the speed of light, physical processes slow down and thus "time" goes slower. You could therefore "travel into the future" by simply letting the universe age faster than you are. Is that right?

Others believe that time is a separate entity that may be able to be "traveled through". But I thought that that was more a philosophical position than I scientific one???

[Robh]

I get it and I'm astounded!

Regards, Rob

[sjastro]

It's only your common garden variety gravitational redshift at work.:)

Steven

[renormalised]

And, Einstein grew lots of those in his garden:P:D

[sjastro]

If he was Richard Feynman he probably would have smoked it.:)

[renormalised]

Until he became "red" in the face:P:D

[Robh]

Add some gravitational nutrients and watch it grow! :)

Rob

[Bobbyoutback]

HeHe Rob :D .

This may interest you :

Hawking came up with the idea of a small black hole evaporating away but leaving a naked singularity behind , that would create the edge of time exposed & be disastrous for physics .
If we took the mass of the earth & squeezed into a small black hole it would have a Schwarzschild radius of only about 10 - 13 cm , thats around the size of the nucleus of an atom !
The time elapsed since the big bang has been calculated enough for this to have happened & thus maybe reverse time itself .

Mentally I,m not equipped well to ponder distortions of time :help:

Cheers Bobby .

[renormalised]

A "black hole" Earth is much larger than that....just plug the numbers into the equation for radius...i.e,

R = 2GM/C^2

See what you get:D

You'll find it's 0.0088m or 9mm

[Bobbyoutback]

Whoops , thats huge compared to what I said, I've given the size of only a billion tonne sized asteroid mass then. :thanx:

Any ideas on faster then light probability , I know the search for tachyons is kinda difficult as they would be moving back wards in time if they were going faster then light because at the speed of light there is no time left to go any faster . :question:

Cheers Bobby .

[Nesti]

Or played Bongos with it.

Or made fun of it.

Or slept with it. :D
Or worse...I'm not going to mention anything about [Feynman] student orgies. :eyepop:

Yes, yes, it's common knowledge, don't shoot the messenger!

[sjastro]

I never knew he was into biological sciences.;)

[renormalised]

Must've had a broad education:P:D

[Nesti]

Old Feynman knew how to live didn't he?!

[renormalised]

Probably too well:P:D

[renormalised]

Anyway, getting back to the topic...Time travel...easy!!!!:D

Don't know what Einstein and all these other simpletons were on about..."grandfather paradoxes", causality violations etc...garbage!!!:D

All you need to do is get into the TARDIS, flip a few switches and viola...anywhere, anytime you like!!!:P:P:D:D