Science Forums

# Time And Time Travel

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I have uploaded a video to youtube and was looking for some feedback. Here is the link.

https://youtu.be/v0lyeu9ostE

It is about time and time travel, mainly questions based on Stephen Hawking. Thanks for watching and for any feedback.

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I have uploaded a video to youtube and was looking for some feedback. Here is the link.

https://youtu.be/v0lyeu9ostE

It is about time and time travel, mainly questions based on Stephen Hawking. Thanks for watching and for any feedback.

I don't do YouTube videos. If you want to raise a topic to discuss, i.e. in your own words, then that would be different.

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Thank you for making the video short. We mostly all have busy lives after all.

It was essentially: "How does one twin age a lot while the other twin does not?"

You mentioned velocity as one of the factors affecting time. Your scenario is not focused on velocity as the cause of time dilation (shifting of time for two frames). Your scenario is referring to gravity as the cause of time dilation. If you orbit a black hole safely, you enter a space-time well (stretched out space-time) where time is stretched out relative to the distance you are to the black hole. This closeness to the black hole, for a period of time, is what causes the traveling twin to experience time differently than the twin on earth. When the traveling twin returns home he has to climb out of the well of the black hole by using an engine to increase his orbital velocity escape orbit and return to earth. The "time travel" (age difference) comes from the gravity and the velocity is not whats important here, unless you are talking about near light speed travel, but, its better to just focus on the gravity effects first. You did mention the comparison of velocity between the two twins. I noticed you asked the question that went something like this "how fast is the twin orbiting the black hole, and how fast is the twin moving on earth"? Your question is arising the from misconception that the velocity of each twin is taken into consideration. This is not possible. Here is why: You have to obey the logic of saying how fast are the twins moving in relation to what? Your making the assumption that there is something that is at absolute rest in which they can both compare to and this is not possible. The relativistic equations that deal with "time dilation" deal with only two reference frames for simplicity and accuracy. Therefore, you have to obey the logic of considering only the velocity relative to the two twins and avoid thinking of a third frame of reference to find out velocities. So you see, one twin has to be considered "at rest" (not moving) while the other is doing the moving. This is because at the beginning of the trip they were NOT moving relative to each other. Then, one twin accelerated away in a ship and became the "mover" in the scenario and in the equation. So that should help you clear away any confusion. Also, the twin would not die from a slow heart beat because the "time travel or dilation" is only observed and is not mutually inclusive. The twin that orbits the black hole will experience time as usual and his heart will beat properly. This is described by both logic and mathematics. In other words, its because space and time are not two things, they are one thing called space-time. It might even be better to call it "the fabric that connects mass". When the twin orbits the black hole he moves through a different quality or expression of the fabric and therefore moves into a different universe so to speak (he travels down a different path).

Next, you mentioned something about backward time travel. This is my view on the matter. It is not possible because it requires something to memorize every tiny single millisecond of action of every particle in the universe and save that memory over a dimension of time. Why? Because backwards time travel assumes you can travel to a new place. This new place is outside of the present moment and therefore outside of the universe, which is inside of a different universe. It doesn't take much thought to realize it would be practically impossible for anything to memorize this much data, not to mention it brings up a large amount of problems about what exactly this memory device is. Some might consider it to be a computer or machine, or possibly an intelligent mind or being that can save time inside itself. These are drastically far out ideas that just create a whole bunch of new problems and questions. Therefore, it is much more acceptable to consider that backwards time travel is not possible due to the requirements to make it possible.

I wouldn't worry about Hawkings idea about future people not traveling to our present. There is that old theory about causing splits in the time continuum if someone were able to do this, and it says that if you traveled back in time you would create a new timeline and never be able to return to your original one. This theory is full of paradoxes and impossibilities with implications of infinity (which makes everything meaningless). So its best to just let go of that idea and accept that backwards time travel is not possible. This way, you can also let go of your concern about the future of humanity coming to an end and never doing time travel. Just understand that space-time is not being put anywhere for storage in order to be retrieved when desired.

Time travel isn't really a thing. It is better to use the words such as time differentiation, time dilation, and time separation. You see, you can't travel into the future, you can only extend your lifetime in relation to your regular lifetime had you not experienced any time separation. You didn't travel into a future, you just went on holidays and lived longer because of the place you went to.

There are many good resources out there that use diagrams, equations and pictures to help make sense of this time thing.

Time is a confusing word. It has several applications or uses. So you have to really get clear on what type of time you are talking about before you start asking questions about it and pondering its nature. So I would suggest if you want to continue the discussion to explain what type of time you would like to understand better. Just try to explain the type of time your interested in.

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I wouldn't worry about Hawkings idea about future people not traveling to our present. There is that old theory about causing splits in the time continuum if someone were able to do this, and it says that if you traveled back in time you would create a new timeline and never be able to return to your original one. This theory is full of paradoxes and impossibilities with implications of infinity (which makes everything meaningless). So its best to just let go of that idea and accept that backwards time travel is not possible. This way, you can also let go of your concern about the future of humanity coming to an end and never doing time travel. Just understand that space-time is not being put anywhere for storage in order to be retrieved when desired.

Another way of thinking about it is that even if traveling back in time were possible, you wouldn't be able to change anything because whatever it is you will do, you will already have done.  This makes time travel irrelevant.

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