Discussion in 'SciFi & Fantasy' started by arfa brane, Apr 9, 2018.

1. ### gooseRegistered Senior Member

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158
I may be misunderstanding what you mean.
But the reference frame I'm using is time. Say an event happens in time A in body Z, and body Y only exists inside body Z at time B. If we were to move body Y into time A, which goes backwards in time? Z or Y? Time doesn't rewind for body Y, it only does so for body Z. The age of Y isn't changing, only the age of Z.... therefore Z is the thing traveling in time.
A - Past
B - Present
Z - Universe
Y - Time Traveler

In my eyes, your example is about velocity. Can't have a negative velocity (negative being backwards in a sense).

3. ### gooseRegistered Senior Member

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ignore this -.-

5. ### DaveC426913Valued Senior Member

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Your post 56 suggests that the passenger always experiences time moving forward, therefore it must be the universe that is moving backward.
I am simply making an analogy to travelling in space.

Turning around in time no more turns the universe around than does turning around in space.

7. ### Michael 345New year. PRESENT is 69 years oldValued Senior Member

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Noooooo
From Counter as per above If the past doesn't exist (it doesn't) how can we remember it?
Note doesn't exist? NOT did exist?
As for memory yes can have physical records which continue existence just like every other physicality stuff. Can also have none physical memory (just thoughts in the head ie non existent)

8. ### Q-reeusValued Senior Member

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Tempted to say 'it always amazes me to see certain folks here repeat an assertion endlessly without once clearly defining it's meaning and context'. But it has long ceased to amaze - just a sad reflection on what generates needlessly long threads that never resolve anything to anyone's satisfaction.
There are two main camps re nature of time:
Eternalists aka 'Block Universe' advocates. They take the mathematical formalism of 4D spacetime to an extreme (or logical conclusion if an advocate)
Presentists aka 'time doesn't exist' or 'there is no past or future only the ever present moment' advocates.

A half-way amalgam of sorts is the 'Crystallizing Block Universe' aka 'Growing Block Universe' pov - the past exists but the future is genuinely open and not set in stone. Basically where a standard interpretation of QM modifies standard Einsteinian 4D Block Universe relativity.

To clear the head (or confuse it even more), it pays to at least be well acquainted with all or nearly all the differing viewpoints and apparent 'clinchers' for each, e.g.
https://plato.stanford.edu/entries/time/
https://onlinelibrary.wiley.com/doi/10.1002/9781118522097.ch21

9. ### hansdaValued Senior Member

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Physical travel to the past may not be possible but the past information can be traced from the present.

10. ### DinosaurRational SkepticValued Senior Member

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Janus58: Your Posts 29 & 31 express concern about not having a frame of reference for motion of the Earth while an alleged time traveler uses his time machine.

The above problem relates to determining how far the Earth moved while the time travel device was used.

How far & relative to what frame of reference are not the real issues. It seems unreasonable to claim that the Earth is stationary while the time traveler moves in time. Hence the time traveler must move in space as well as time in order to remain on Earth.

11. ### C CConsular Corps - "the backbone of diplomacy"Valued Senior Member

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Back in the 1950s, Isaac Asimov addressed that in The End of Eternity. But I'm not sure he was the first to do so in a fictional work.

That "a time-traveler must also be a space-traveler" might arguably seem more applicable to the "single leap or teleportation across the decades / centuries" type stories. Rather than simply "accelerating" through the future or past as the time-traveler may have done in HG Wells' 1895 novel. In essence, the latter would be an approach of "still moving along with the Earth change by change" minus the normal snail-pace of temporal modifications. Regardless of the plausibility of such in the real world or non-fictional treatises by scientist authors. (While not remaining in a specific location on Earth, a spaceship traveling close enough to light speed to garner relativistic effects would also be surfing within the rest of the cosmos and its incremental changes, in its version of carrying an occupant to the future minus most of the personal experiences and aging process transpiring back home.)

~

12. ### DaveC426913Valued Senior Member

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You say no, and then you repeat what I said almost verbatim?

As for memory yes can have physical records which continue existence just like every other physicality stuff. [/QUOTE]

Er. What makes you think the thoughts and memories in your head are non-physical? They're stored, recalled and experienced as bio-electric chemistry. How is that qualitatively different than something stored as magnetic ones and zeros?

13. ### Janus58Valued Senior Member

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But that's the point. There is no definite answer to how far the Earth moved while the device was used. If you go back 24 hours. do you appear 2,592,000 km from the Earth ( the distance traveled by the Earth relative to the Sun), 19,872,000 km from the Earth ( the distance our solar system moved relative to the center of the galaxy) or some distance that is a combination of the two? There is no absolute definitive answer to the question: "How far does the Earth move in 24 hrs." That question can only be answered as "relative to some reference frame". But every reference frame is equally valid. Saying that you must move in space as well as time is a meaningless statement.
This is one reason that, in my opinion, any remotely feasible method of time travel would require something physical at both entry and exit.

14. ### Michael 345New year. PRESENT is 69 years oldValued Senior Member

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True.
The most common form I think is called a book

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16. ### Michael 345New year. PRESENT is 69 years oldValued Senior Member

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Because they are not physical they are concrpts
CONCEPTS

Think we are back to the lie detector machine and or the EEG - while the EEG picks up the electrical activity of the brain - it has no way of extracting the thought

17. ### Michael 345New year. PRESENT is 69 years oldValued Senior Member

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Gawdzilla Sama likes this.
18. ### DaveC426913Valued Senior Member

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They're encoded as bio-electrical patterns.

Unless you;re one of those soul-believers.

Who said anything about extracting them? The thoughts in your head are a product of those bio-electrical patterns. Your memory is stored physically, even if we don;t yet have a way of reading them.

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20. ### arfa branecall me arfValued Senior Member

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In Travelers, a team is injected into the past so it can deflect a comet (or asteroid) which otherwise causes massive tidal waves and a global catastrophe.

So how much mass and momentum would the bolide need to have, to first of all represent a catastrophic event, and how much energy would you need to project in order to deflect it safely? In the show, the deflection is achieved with an X-ray laser, powered by 10.2 g of antimatter, so the amount of energy available is $10.2 \times 10^{-3} kg \times {(3.0 \times 10^8ms^{-1}) }^2 = 10.2 \times 10^{-3} kg \times 9.0 \times 10^{16}m^2 s^{-2} = 9.18 \times 10^{14} J$

Last edited: Apr 14, 2018
21. ### Q-reeusValued Senior Member

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Feeling especially bored? Because imo you are now hijacking your own thread.

22. ### DaveC426913Valued Senior Member

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Right. So, you acknowledge that your thoughts and memories are physically encoded in your physical brain.

23. ### arfa branecall me arfValued Senior Member

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So the question here is: is about $10^{15}$ Joules enough energy to deflect a comet? Maybe, but deflecting the comet also means having to focus this energy on a known location.

Well, here's a problem, even if the future "knows" when the comet enters the earth's atmosphere and when it strikes the ocean it lands in (because both are known accurately), how could it know where the comet was when the deflection beam is fired? This comet doesn't get detected until it's too late, so there must be some really cool quantum processing goin' on somewhere.

Unless of course, it is possible to retrodict the comet's position from a sufficiently large set of measurements taken from the moment of first detection.