Time Travel possible or not?

[TenEightyOne]

Because that is the earliest possible point for time travel to exist, so to say. Any time before that, and the technology basically doesn't exist, even if the machine has partial functionality.

To follow that through logically... if a 50-year-old were to travel back 10 years then would they become 40 years old? As it is there's no reason that a "time machine" as it's understood to be in popular literature wouldn't be able to go anywhere. The idea is that the machine and its contents move unaltered across time.

 

[Lain]

Having read the book, Time Travel in Einstein's Universe, I'd say...

Time travel to the future? Probably possible.
Time travel to the past? Probably impossible.

It's been ages since I've read that book though, so don't ask me for specifics on why. Not to mention the possibility that the book, like any other, isn't infallible. But it was a good read, I recommend checking it out.

 

[polysmut]

Having read the book, Time Travel in Einstein's Universe, I'd say...

Time travel to the future? Probably possible.
Time travel to the past? Probably impossible.

It's been ages since I've read that book though, so don't ask me for specifics on why. Not to mention the possibility that the book, like any other, isn't infallible. But it was a good read, I recommend checking it out.

I read Relativity by Einstein many years ago & still don't feel like I know exactly what it's all about.

 

[TheCracker]

Okay, so here's another thing. Let's imagine we created a time machine, but it's static to a particular coordinate on the earth. It can travel back and forth through time but must remain in the place it was constructed. What would happen if we went back in time, but in the past there's actually a building or solid object, occupying the space that was clear when the machine was first built. Would the time machine merge with the building or solid object?

 

[TenEightyOne]

Okay, so here's another thing. Let's imagine we created a time machine, but it's static to a particular coordinate on the earth. It can travel back and forth through time but must remain in the place it was constructed. What would happen if we went back in time, but in the past there's actually a building or solid object, occupying the space that was clear when the machine was first built. Would the time machine merge with the building or solid object?

Given that you have the ability to find the Earth in space then you'd just use similar tech to shuffle the coordinate to "clear" ground space, no? If the merge were attempted then you'd likely have a nuclear explosion.

Arguably you'd get the even if you merged a solid and a gas, of course.

 

[justin credible]

@justin credible
Would you consider prophecy - for instance Nostradamus - to be a form of time travel?

Interesting point but up to now my limited knowledge on it makes me say no. The guy is hailed as a prophet but for me his sayings are to hit and miss to accept as correct or time travelling.

 

[Dotini]

Interesting point but up to now my limited knowledge on it makes me say no. The guy is hailed as a prophet but for me his sayings are to hit and miss to accept as correct or time travelling.

Other possible forms of time travel might be clairvoyance, remote viewing, UFOs, ghosts, poltergeists, Bigfoot and infestations of garden fairies. The hypothesis is that they are all "psychic" manifestations, i.e., related to human consciousness.

 

[justin credible]

Other possible forms of time travel might be clairvoyance, remote viewing, UFOs, ghosts, poltergeists, Bigfoot and infestations of garden fairies. The hypothesis is that they are all "psychic" manifestations, i.e., related to human consciousness.

Agree 100% I have never seen any of the above ghosts bigfoots or experienced any clairvoyance etc.
I always thought it is the mind playing tricks on you.
Take ghosts for instance people see them when there usually alone may be a bit tired usually dusky time of the evening Why don't I see one ever when I am in say Tesco shopping? or standing in a football crowd seconds before kick off I never see one run across the pitch.

No for me they can't be time travellers as I truly believe it is as you said all related to human consciousness.
Hypnotherapy works when we are resting in a trance state and we accept what we are told by the therapist much the same line of seeing ghosts etc to me make you think you really did experience it, subconscious mind acting the pratt like dreams.

Time travel to me is the fascination of the time machine and having the ability to go forwards and backwards to any given time, I know impossible but future time travel might be able to be done as I have read so that feeds my interests.
Fairies Ghosts no not for me.
I will believe them if I can see and touch them.

 

[Dotini]

Time travel to me is the fascination of the time machine and having the ability to go forwards and backwards to any given time

In my youth, I saw the most excellent film, The Time Machine, by HG Wells. There was the most ornate, baroque time machine. There were the beautiful Eloi and horrible Morlocks!

 

[TenEightyOne]

In my youth, I saw the most excellent film, The Time Machine, by HG Wells. There was the most ornate, baroque time machine.

Proper brass'n'oak steampunk before hipsters were a thing

 

[Danoff]

In my youth, I saw the most excellent film, The Time Machine, by HG Wells. There was the most ornate, baroque time machine. There were the beautiful Eloi and horrible Morlocks!

Proper brass'n'oak steampunk before hipsters were a thing

 

[Robin]

That remake was bizzare, and who let Samantha Mumba act!

 

[TenEightyOne]

who let Samantha Mumba act!

Certainly not her.

 

[Danoff]

That remake was bizzare, and who let Samantha Mumba act!

I liked it, though I automatically give movies a few extra points for being post-apocalyptic. It gets a few more bonus points for having a great soundtrack.

 

[Robin]

I liked it, though I automatically give movies a few extra points for being post-apocalyptic. It gets a few more bonus points for having a great soundtrack.

I felt the CGI (especially that scene when the Moon starts to break up and he goes way into the future), set design and the design of the time machine itself were great but the script, slightly nonsensical plot and the acting for me was I don't quite remember the soundtrack, been a while since I last watched it.

I wouldn't want to go forward, we might end up in the world as shown in 'Idiocracy'

 

[Imari]

Barely related, but there's also an idea that there's only one electron in the entire universe, and it travels around in time to be everywhere that it needs to be.

https://en.wikipedia.org/wiki/Retrocausality#Modern_particle_physics

I have no idea how well it holds up, but I love the idea.

 

[Obelisk]

Barely related, but there's also an idea that there's only one electron in the entire universe, and it travels around in time to be everywhere that it needs to be.

https://en.wikipedia.org/wiki/Retrocausality#Modern_particle_physics

I have no idea how well it holds up, but I love the idea.

So we're all sharing a single electron?

 

[TenEightyOne]

https://en.wikipedia.org/wiki/Retrocausality#Modern_particle_physics

Yeeees. Might come back to that later

(or earlier, to be on-topic)

 

[DolHaus]

Well there is also quantum entanglement which some believe suggests that the big bang never happened and everything is still in one place which means that neither time nor distance exist so both time and travel are irrelevant

 

[justin credible]

I felt the CGI (especially that scene when the Moon starts to break up and he goes way into the future), set design and the design of the time machine itself were great but the script, slightly nonsensical plot and the acting for me was I don't quite remember the soundtrack, been a while since I last watched it.

I wouldn't want to go forward, we might end up in the world as shown in 'Idiocracy'

I would love to travel to the time set in Idiocracy I would be like Ricky Gervais in The invention of Lying,
Can you imagine the fun you could have? it would be a world of enjoyment and that's not to mention the naughty bits

 

[Blitz24]

Well there is also quantum entanglement which some believe suggests that the big bang never happened and everything is still in one place which means that neither time nor distance exist so both time and travel are irrelevant

But then how would aging work? Too many questions that idea opens up.

 

[DolHaus]

But then how would aging work? Too many questions that idea opens up.

How do you mean?

 

[Blitz24]

How do you mean?

If time doesn't exist then how would aging really exist?

 

[DolHaus]

If time doesn't exist then how would aging really exist?

What is ageing though?

 

[Danoff]

Well there is also quantum entanglement which some believe suggests that the big bang never happened and everything is still in one place which means that neither time nor distance exist so both time and travel are irrelevant

They exist. We give names to things we observe, and these are the names we've given to the things we observe. In effect, we've given two names (time and space) to the same phenomenon (spacetime). You might say that spacetime doesn't exist either, but whatever its true nature is, we've named what we observe.

Pretending, for a moment, that you do not travel through time or space, that what only exists is right now, and that there is no direct link between past memories and future memories, space and time still exists as descriptions of perception.

Forgetting quantum entanglement for a minute (because that's stuff is confusing). Let's talk about black holes.

Where is a black hole? That's a confusing question, it's a singularity in spacetime. It's about as confusing as saying when is a black hole. As you travel into a black hole, time slows down for you relative to the rest of the universe. In front of you is the beginning of the black hole (time is moving so slowly at the center of a black hole compared to you right now, that it just began), and behind you is the end of the universe (time is moving so fast outside of the black hole compared to the inside that all of time transpires while you fall in). So you never hit the bottom (compared to our perception of time). Black holes expose the relativity of the experience of space and time. They exist without space or time, which led me to make this post about black holes. Where are they? Nowhere, anywhere. When are they? Never, always.

Our perception of time is directly analogous to our perception of space. We perceive time because of where we are, and we are where we are because of our perception of time. We surf the surface of spacetime and hope not to fall off (into a black hole) leaving spacetime altogether.

 

[DolHaus]

They exist. We give names to things we observe, and these are the names we've given to the things we observe. In effect, we've given two names (time and space) to the same phenomenon (spacetime). You might say that spacetime doesn't exist either, but whatever its true nature is, we've named what we observe.

Pretending, for a moment, that you do not travel through time or space, that what only exists is right now, and that there is no direct link between past memories and future memories, space and time still exists as descriptions of perception.

Forgetting quantum entanglement for a minute (because that's stuff is confusing). Let's talk about black holes.

Where is a black hole? That's a confusing question, it's a singularity in spacetime. It's about as confusing as saying when is a black hole. As you travel into a black hole, time slows down for you relative to the rest of the universe. In front of you is the beginning of the black hole (time is moving so slowly at the center of a black hole compared to you right now, that it just began), and behind you is the end of the universe (time is moving so fast outside of the black hole compared to the inside that all of time transpires while you fall in). So you never hit the bottom (compared to our perception of time). Black holes expose the relativity of the experience of space and time. They exist without space or time, which led me to make this post about black holes. Where are they? Nowhere, anywhere. When are they? Never, always.

Our perception of time is directly analogous to our perception of space. We perceive time because of where we are, and we are where we are because of our perception of time. We surf the surface of spacetime and hope not to fall off (into a black hole) leaving spacetime altogether.

Do you know what (scientifically speaking) a black hole is?

 

[Danoff]

Do you know what (scientifically speaking) a black hole is?

A collapsed star.

 

[DolHaus]

A collapsed star.

Correct, A star that got so massive that it collapsed in upon itself due to its own gravity. This collapse doesn't make a hole at all, the mass of the formerly gigantic star is smooshed together into a significantly smaller area which is incredibly dense. Now, because it has the same mass as before it still creates the same amount of gravity but in a much more focused area, this focussed force is so strong that not even light can escape it (hence the blackness). In the same way that when you travel incredibly fast time passes faster around you the opposite thing happens with massive gravitational forces, the closer you get to the massive force the slower time will pass around you. While time may be relatively slower it will never stop and it will never go backwards.
Black holes aren't that mysterious and they most likely don't lead anywhere, anything that gets sucked in just gets compressed. They are located exactly where the star was (either at the centre of a system or orbiting a larger star), they exist from a definable point in time, you can't fall into it because there is nothing as dense in the rest of the universe (same reason you don't sink into the centre of the earth). They are very difficult to find because they are essentially invisible and would absorb any signals you could send its way, there could be one not too far from our own solar system but we just woulnd't know it was there because we can't see or detect it.
While fascinating they are a simple cause and effect process rather than how Sci-Fi often glorifies them, they are no more powerful or dangerous than the sun that they once were because they have the same mass and gravity, anything that was going to get sucked in would have been sucked in before the star collapsed.

 

[Famine]

Correct, A star that got so massive that it collapsed in upon itself due to its own gravity. This collapse doesn't make a hole at all, the mass of the formerly gigantic star is smooshed together into a significantly smaller area which is incredibly dense. Now, because it has the same mass as before it still creates the same amount of gravity but in a much more focused area, this focussed force is so strong that not even light can escape it (hence the blackness). In the same way that when you travel incredibly fast time passes faster around you the opposite thing happens with massive gravitational forces, the closer you get to the massive force the slower time will pass around you. While time may be relatively slower it will never stop and it will never go backwards.
Black holes aren't that mysterious and they most likely don't lead anywhere, anything that gets sucked in just gets compressed. They are located exactly where the star was (either at the centre of a system or orbiting a larger star), they exist from a definable point in time, you can't fall into it because there is nothing as dense in the rest of the universe (same reason you don't sink into the centre of the earth). They are very difficult to find because they are essentially invisible and would absorb any signals you could send its way, there could be one not too far from our own solar system but we just woulnd't know it was there because we can't see or detect it.
While fascinating they are a simple cause and effect process rather than how Sci-Fi often glorifies them, they are no more powerful or dangerous than the sun that they once were because they have the same mass and gravity, anything that was going to get sucked in would have been sucked in before the star collapsed.

Did you just try to educate a spacecraft flight engineer in stellar phenomena?

Incidentally, these things... not quite the case:

the mass of the formerly gigantic star is smooshed together into a significantly smaller area which is incredibly dense

they are no more powerful or dangerous than the sun that they once were because they have the same mass and gravity

Black holes aren't that mysterious

The mass isn't just in a smaller area and incredibly dense - it's in zero area and is infinitely dense, or a singularity (an area with mass but no spatial dimensions). Black holes are phenomenally mysterious because they represent an utter breakdown of all physics - they distort spacetime to such an extent that they fracture it. All mass bends spacetime (see general relativity) but a singularity bends it to the point that the dimensions you know (length, breadth, height) are no longer at right angles to one another but parallel. The "hole" is merely the event horizon, and beyond the event horizon is zero spacetime.

This leads to the things @Danoff describes. Stand just inside the event horizon and there is no time for you. Despite the phenomenal curvature of spacetime (and thus gravitation) sucking you in, you'll never get any closer to the singularity. Turn and face the outside and you will watch the universe experience all of its time simultaneously.

Though given that your physical form will have been pulled into a fine thread (due to the increasing curvature of spacetime) over billions of years as you approached the event horizon, you wouldn't actually see much of anything.


Black holes may be the strangest things in our universe, because they break it.

 

[Danoff]

Correct, A star that got so massive that it collapsed in upon itself due to its own gravity. This collapse doesn't make a hole at all, the mass of the formerly gigantic star is smooshed together into a significantly smaller area which is incredibly dense. Now, because it has the same mass as before it still creates the same amount of gravity but in a much more focused area, this focussed force is so strong that not even light can escape it (hence the blackness). In the same way that when you travel incredibly fast time passes faster around you the opposite thing happens with massive gravitational forces, the closer you get to the massive force the slower time will pass around you. While time may be relatively slower it will never stop and it will never go backwards.
Black holes aren't that mysterious and they most likely don't lead anywhere, anything that gets sucked in just gets compressed. They are located exactly where the star was (either at the centre of a system or orbiting a larger star), they exist from a definable point in time, you can't fall into it because there is nothing as dense in the rest of the universe (same reason you don't sink into the centre of the earth). They are very difficult to find because they are essentially invisible and would absorb any signals you could send its way, there could be one not too far from our own solar system but we just woulnd't know it was there because we can't see or detect it.
While fascinating they are a simple cause and effect process rather than how Sci-Fi often glorifies them, they are no more powerful or dangerous than the sun that they once were because they have the same mass and gravity, anything that was going to get sucked in would have been sucked in before the star collapsed.

Not quite.

The gravitational focus is enough to stretch spacetime to a degree that it holds no meaning relative to the remainder of the universe. If we could see into a black hole we'd see that it has just formed, and everything that has fallen into it is still falling, and will never appear to reach it, slowing down as it gets closer to the center - asymptotically approaching zero speed from our perspective. They are like stopped time across infinite space (again, from our perspective). Where they exist in our universe and when is a meaningless question. The place where that star collapsed is no longer well defined.

Edit:

@Famine, admittedly as a spacecraft engineer (navigator) I know more about this than they lay person, but I'm no astrophysicist unfortunately. I run into the end of my understanding pretty quickly.