# Is time travel possible based on theory?

Discussion in 'Physics & Math' started by Saint, Jun 9, 2019.

1. ### Write4UValued Senior Member

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IMO,
a state of superposition is always theoretical and cannot ever be the result of the collapsed state. That's when the superposition gets sorted out in reality as either A or B, never both at the same time.

Superposition is a "potential", which implies a possible choice between two opposing preliminary states.
potential is defined as: "That which may become reality"

3. ### Michael 345New year. PRESENT is 72 years oldlValued Senior Member

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From my understanding it is not a single component you are trying to observe

It is a mix of components and when observations are made you see one OR the other

Did I get that right?

Looks good

5. ### Write4UValued Senior Member

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18,777
I think so.
As I understand it, the observation is what collapses the wave function and resolves the superposition into one state or the other.

p.s. I have not yet watched this but may be a good companion to the book.

What is Relativity? An Introduction to Einstein's Theory with Dr. Jeffrey Bennett

Last edited: Aug 25, 2019

7. ### Michael 345New year. PRESENT is 72 years oldlValued Senior Member

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So Schrodinger’s cat works if you have both a live AND dead cat in the box, and the alive/dead cat pair oscillate between being in the box or somewhere else

Opening the box stops the oscillation and you see one OR the other

Thought bubble

If you flap the lid fast enough would your observations finish up 50/50 alive/dead?

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8. ### Write4UValued Senior Member

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18,777
LOL, I think you have a cat in the box which may be alive or dead. The superposed states are theoretical states. It is a thought experiment.

Let us not forget Schrodinger posed the problem to show the inherent contradiction.
https://wtamu.edu/~cbaird/sq/2013/07/30/what-did-schrodingers-cat-experiment-prove/

9. ### Write4UValued Senior Member

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Suppose the cat died but we are traveling back in time? Will the the cat magically revive at some point, return to a state of superposition?

10. ### Michael 345New year. PRESENT is 72 years oldlValued Senior Member

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Doubtful

Watched the video. Put it up on the 65" TV, good quality. Fell asleep last ¼ hour

Not the best presenter, but from the bit of the book have read, a better author. Regardless thanks for the link

Got couple of gems from the video. One was the 50 year round trip at 99.9% speed of light to Alpha Centauri, the Earth twin ages 50, the astronaut 7 years

Unfortunately not spelled out HOW. Some mention of the speed of light being the absolute, also mentioned was the fabric of space-time being curved though which the planets roll as explaination of gravity

Time to hit the books again

Cheers

Coffee moment

11. ### pluto2BannedValued Senior Member

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Time travel is probably only possible in a science fiction world or in a fantasy world.

But I have to tell you that I'd choose a science fiction world like Star Trek or Stargate over the world we live in right now at any time because this world very much sucks and I don't like it because it's crazy.

Last edited: Aug 25, 2019
12. ### Write4UValued Senior Member

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And what is it about Star Trek and Stargate that attracts you? Kirk and Spock cleaning up crazy situations on different planets instead of different neighborhoods on earth?

Not much different, just on a larger scale!

13. ### pluto2BannedValued Senior Member

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I was just kidding. In the movies anything is possible.

But time travel is actually not possible under any law of physics that we know of. And physics and only physics dictates what is possible or not in the very end.

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14. ### QuarkHeadRemedial Math StudentValued Senior Member

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Fortunately for science, opinions do not count - only observations and conclusions drawn from them do.
Agreed, superposition is not the RESULT of a collapsed state. One can argue (like Niels Bohr) that, given a state can be represented as a wave function, then measurement trivializes the wave function function so that it is everywhere except at a single point in state space
Whose "reality"? Yours or observational science's?

You are privileged to have an insight into "reality" without observation!!

15. ### Write4UValued Senior Member

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18,777
QuarkHead, that's just a meaningless knee-jerk response. Opinions don't count? How about knowledgeable opinions? If the opinion is in agreement with "official scientific concensus", it still doesn't count anyway?
And it is your observation that I made those statements without observation? Your observation is science and mine is pure speculation?
AND HOW DO YOU KNOW THAT! SPECULATION?
https://www.merriam-webster.com/dictionary/potential

Potential: "that which may become reality", are we clear on this? Or do you have the privilege to have insight to someone's "knowledge" without observation, which according to you is a nono, tsk,tsk,tsk.

If you need clarification on anything, just ask, and I'll explain, ok.

Last edited: Aug 25, 2019
16. ### QuarkHeadRemedial Math StudentValued Senior Member

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I certainly shall, thank you. How about you start with Quantum Electrodynamics, which is causing me some difficulty - or rather the mathematics is. Please clarify

17. ### Write4UValued Senior Member

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You mean QED is an incomplete theory which requires greater explanation?
Isn't that precious. I offer to explain anything I said which is not instantly clear and you come back with a question which I did not address to begin with and which apparently no one can answer, right?

That's a disingenuous question, not posed in good faith.

18. ### QuarkHeadRemedial Math StudentValued Senior Member

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Ah now, you flatter me. That I am struggling with the mathematics of Quantum Electrodynamics hardly seems to suggest it is an incomplete theory - I am far from being that clever!

19. ### Write4UValued Senior Member

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Ahh. Well my knowledge of mathematics extends only to advanced bookkeeping, so I'm afraid I can be of no assistance in the maths of QED...

I am happy when I understand the concepts behind a theory, let alone the maths.

I do have understanding of the "mathematical function". That helps when observing the Natural Order of the universe.

I am struggling with the concepts (and maths) of Bohmian Mechanics which, like QED, also resolves the conflict between QM and GR. It does away with the notion of the particle/wave duality, which is the great sticking point.

Are QED and Bohmian Mechanics in competition or are there common denominators which may offer compatibility?

Last edited: Aug 25, 2019
20. ### Write4UValued Senior Member

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Observational science , of course. My observational science is no different than anyone else's.

Better question would be, what happens in a multiverse? Do different universes share the same quantum event? Can A be B in a different universe? If so, are the events in each universe related at all or occur totally independently from each other?

And what are the Potential Implications of that "perspective".....

I have empathy with this presenter and his perspective on the physical world.

Last edited: Aug 25, 2019
21. ### phytiRegistered Senior Member

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680
If a particle has 2 possible states, a or b, you don't know which one is current unless you perform an observation. My simple analogy of superposition is a coin flipped into the air. While in motion it can be considered in a H and Y state. When it comes to rest, an observation reveals either H or T.

In the case of Schrodinger's cat, the uncertainty is not with the cat, but the decay of the radioactive material.

Both cases tend to reveal the 'wave function' as a lack of knowledge about a system, and not about the system itself.

With time defined as a dimension, it's not surprising that someone will ask, can we go there.

22. ### TheFroggerBannedValued Senior Member

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Michael345, if time does not exist, then in the following example how is it possible to travel from one to two:

2-----------
xxxxxx/
xxxxx/
xxxx/
xxx/
xx/
x/
/
-------1

?

A human being IS time: it is within us. Time is subjective, and travelling thus means that by traversing time, YOU will discover what YOU have done; it doesn't mean an absence of action results in an action. If you do not do something, it will not happen.