Should we time travel into the past?

What if a time travel organization keeps a copy of time travelers in suspended animation to be revived if they get erased from history? Beyond our current technology, but then so is time travel.

 

As for changing the past, it might not be possible in classic physics but it is possible in quantum physics.

 

Not sure how it would be possible, all matter is accounted for 100% of the time. The future you would be stepping back in time when the matter that comprised you would be constituted in something else...

 

I don't think the universe would/could suffer the paradox. I think travelling to the past would necessarily create divergent timelines/alternate realities.

 

The OP assumes a Back to the Future scenario, where there is only one timeline, and changes in the past ripple out and change the future. I would think the more likely scenario is the Avengers: Endgame one, in which travel to the past creates a divergent history.

 

I like the idea in the original Time Machine movie. When he spoke of moving in the first three dimensions but being trapped in the fourth. If we could move backwards and forwards in the fourth.

 

Let me know if that's not what I said.

 

I already said that!

Reported.

 

Im reminded of quote from Futurama:

'I can't believe I wasted 20 years trying to invent that damn time machine!'

'If only it had worked, you could go back and stop yourself from wasting your time on it.'

 

This is cheating a bit, but you can change the past by re-writing it, airbrushing out the bits you don't like. Some people like to do that with holocaust denial and conspiracy theories. Trump's helpers invented alternative facts, and Trump lies all the time, long and loud.....

 

Wouldn't that require infinite matter to constitute the new time frame, and to allow for additional divergences? Isn't it more likely that there is a universal time, a measure between events, that can and would only work in one direction, and any notion of time travel would actually just be movement through space/time on a perceived level that had no potential to change events that already occurred? The very notion of any type of time travel requires a significant number of other theories to work as well, almost none them have ever been proven.

 

That would be travelling to someone elses future.....not yours. depending on perspective they are travelling to your past.

 

No, but I've always liked the concept put forth in Arthur C. Clarke's The Light of Other Days, where physical travel was impossible, but any point in the past could be viewed and recorded via an artificial wormhole...

 

Well the OP asks, "should we?" not can we, since we obviously can't. It's just a thought experiment, but to follow along with the thought experiment, you need to know what kind of time travel you have.

 

There are serious theoretical physicists that see this idea of forking off nearly duplicate universes as a possibility.

I don't know how they figure that is possible. It might include that space without mass is still energetic.

 

In your opinion it is a moot point. What if you're wrong?

 

It results from The Many World's Theory. And I don't know of any explanation for how it happens, just that we have physical evidence that alternate universes exist.

 

IF you orbit a black hole, you would not feel any gravitational forces - just like astronauts orbiting earth. Gravity exists at orbital distances. But the craft is falling towards the earth as fast as the curve of the earth moves away, due to the forward motion of the craft. Since you are in constant free fall, you feel no force from gravity.

There are mathematics that allow for a time machine given enough energy. But even those hints at time travel say that you can only go back in time until the point that the time machine was first turned on.

A physicist named Mallard it trying to make a time telephone by stirring spacetime using LASERS. This is hoped to create a phenomenon known as frame dragging, which is the same effect that moves an astronaut back in time when circling a black hole. It happens on earth as well. We have to compensate for frame dragging in satellites, but only for extremely small increments of time. [actually, that may not be correct. It may be that we've only detected it. I would have to check]

If he is successful, he might be able to communicate with himself in the past. At least, that's the idea.

If we can open a stable wormhole, then in principle time travel might be practical.

Some have argued that by opening a stable wormhole, we [the world] would be destroyed by an energy pulse that approaches infinity. I don't remember the precise argument for that but I know it has been considered.

 

Orbiting a black hole does get more complicated because the force of gravity can change dramatically over small distances. This is why you would get spaghettified if you fell into a black hole [say feet first] - you would be stretched and ripped into pieces as your feet are pulled harder than your head.

So if you plan to orbit a black hole, you should probably do it face down. You would still feel a change in gravity from zero, to something much larger, over a short distance. The gravity can only measure zero at one point; as measured from the center of the black hole.

 

Time travel, according to Ray Bradbury. This is my favorite short story from science fiction. It was first published in 1952

 

There is one reason to time travel to the past

 

I don't make any such assumptions. That is just one possibility.

That's part of the intrigue. What risks are we willing to take given that we don't know and can't know for sure until [if] it's done, what will happen. Obviously we wouldn't intentionally create a wormhole if the calculations show it will destroy us. But if it appears to be workable, there are still huge risks.

 

I don't know of any evidence that there is another universe/world.

There have been some ideas, such as looking for evidence of gravitational effects and of circles that could possible result from "collisions". AFAIK, these have all failed after serious investigation.

 

What if you could go back and give yourself advice. What would it be?

 

Then study the Many Worlds Theory. It doesn't arise from nothing. We see effects at the quantum level that can't be explained classically. This leads to the evidence for parallel universes. It isn't a terribly popular theory in its strong form, but it has been around for a long time now.

One example is a particle existing at two places at once. Since this isn't possible [even though we've done it], TMWT says we are observing one particle from another reality.

There are many variations that range from the strong interpretation, to much more mind-friendly versions that don't drive Standard Model theorists crazy.

So far the answer is, we don't know.