Traveling using space curvature

[Papo1111]

Hi everyone.

I'd like to verify my thoughts about travellig through space using a space curvature.

Imagine you have a spaceship and you want to travel some distance. Your ship launches an object into space that has huge mass and density. It curves space. Now, you enter the curved space and keep moving through it. And as you are traveling through the curved space you should actually travel more distance in less time compared to the ship that is outside of the spacetime curvature but traveling with the same velocity (Lets say that time dilation is not working for a second). Because (if I'm not mistaken) the space around that object with huge mass and density should shrink.

Now here comes my question: Is this working? Am I correct?

And sorry for my english (if something was wrong).

PS: I'm not sure if this is undergrad or just hig scool topic so I picked undergrad.

 

[Orodruin]

Your view of how general relativity works is hugely oversimplified and overpopularised. You cannot do physics like that, you need to actually learn the appropriate framework to do so. To learn the appropriate framework for GR you typically need to have a graduate level understanding of physics and mathematics.

 

[Ibix]

You might want to look up the Alcubierre drive. It doesn't work at all like what you are describing, and probably requires a number of impossible things, but it at least has mathematical rigour.

As Orodruin says, verbal descriptions of general relativity are nowhere near precise enough to work with. Many are just wrong. You need to learn the maths if you want to do development work.

 

[Papo1111]

Well... I am just going to attend high school. I'm trying despreatly hard to undertsand all of these things. It came up to my mind some time ago and since there is nbody to ask i decided to post it. Thanks for the tips though.

 

[Orodruin]

Im just going to attend high school. I'm trying despreatly hard to undertsand all of these things. It came up to my mind some time ago and since there is nbody to ask i decided to post it.

Don’t stress about it. You have plenty of years ahead of you to learn advanced physics. Just work hard with the basics in maths and physics, they will be essential for learning higher level physics.

 

[Papo1111]

Don’t stress about it. You have plenty of years ahead of you to learn advanced physics. Just work hard with the basics in maths and physics, they will be essential for learning higher level physics.

Yeah, you're totally right. Thanks for giving me courge again. Sorry to bother you, but could you suggest some great book about physics generally or about Special and General Reltivity? Theese things really interests me.

 

[Orodruin]

Another hopefully helpful tip: I know that it is tempting to try to think up your own ideas from what you read in popular science. It is of course good to think and imagine to keep your brain occupied, but be aware that most of what you think about is likely to be suffering from misconceptions coming from the inevitable fact that popular science is intended to entertain and dazzle, not to teach. Learn physics the proper way before you start taking your own ideas too seriously.

Yeah, you're totally right. Thanks for giving me courge again. Sorry to bother you, but could you suggest some great book about physics generally or about Special and General Reltivity? Theese things really interests me.

If you want to learn actual relativity you most likely have quite some way to go, just start with learning the basics in classical mechanics, etc.

 

[Papo1111]

Thanks.

You're a big help.

 

[Ibix]

You might like Ben Crowell's Relativity for Poets, which is pretty honest about both what it can teach you without maths and what it cannot. It's free to download from http://lightandmatter.com/poets/. @bcrowell was a former poster here.

Ultimately, physics is like anything else - to work with it takes years of practice and study. It's like music. Anyone can listen to someone else playing a symphony. Anyone can pick up a flute and make a squeak. Getting to be able to play a symphony yourself means a lot of practising of scales and simple tunes and then more complex ones. And still practising your scales.

 

[pervect]

Hi everyone.

I'd like to verify my thoughts about travellig through space using a space curvature.

Imagine you have a spaceship and you want to travel some distance. Your ship launches an object into space that has huge mass and density. It curves space. Now, you enter the curved space and keep moving through it. And as you are traveling through the curved space you should actually travel more distance in less time compared to the ship that is outside of the spacetime curvature but traveling with the same velocity (Lets say that time dilation is not working for a second). Because (if I'm not mistaken) the space around that object with huge mass and density should shrink.

Now here comes my question: Is this working? Am I correct?

And sorry for my english (if something was wrong).

PS: I'm not sure if this is undergrad or just hig scool topic so I picked undergrad.

If you change space curvature to space-time curvature, both wormholes and the Alcubeirre warp drive (as previously mentioned by another poster) illustrate that it is possible to travel through space via space-time curvature.

In the context of General relativity, space curvature (as distinct from space-time curvature) depends on the observer, because space and time are intertwined. For instance, in the Schwarzschild metric representing a static, hovering, observer, there is space curvature around a massive body, while around the very same mass, in Painleve coordinates which represent an observer in free-fall, there is no spatial curvature. In both cases, though, the space-time around the black hole is curved.

We can only give answers in the context of General relativity here - or possibly some other peer-reviewed scientific theory of gravity (though other theories are not nearly so well studied). We can't give answers about someone's personal theories - it's up to them to understand their personal theory well enough to be able to make predictions from it, that isn't something we can help with.

Hopefully, however, the answer to the rephrased question (replacing space curvature with space-time curvature) according to General relativity will be satisfcatory.

An interesting question is whether any of the exotic methods for traveling through space that General relativity allows might also allow time travel, since space and time are so closely related in the theory. The answer to that isn't really clear at this point. It's an interesting quesiton, but a bit off-topic.

 

[berkeman]

could you suggest some great book about physics

This small book is inexpensive and would be very interesting for you, given where you are in your physics education right now. See if your local library has a copy, or just buy a copy off of Amazon (or ask for it for your birthday present)

"Thinking Physics" by Lewis Carroll Epstein: https://www.amazon.com/dp/0935218068/?tag=pfamazon01-20

 

[FactChecker]

Yeah, you're totally right. Thanks for giving me courge again. Sorry to bother you, but could you suggest some great book about physics generally or about Special and General Reltivity? Theese things really interests me.

A couple of books that you might like and will not overwhelm you with advanced math are: "Mr Tompkins in Paperback" by George Gamow and "Relativity Visualized" by Lewis Carroll Epstein.
But you should be aware that you can not take these books too literally. They are good efforts by good physicists to make the concepts understandable at a casual level.

 

[PAllen]

Another example of a light approach to GR, but still mathematical, is https://www.amazon.com/dp/B00L6F8J6K/?tag=pfamazon01-20.

 

[PAllen]

A other compact, reasonably light approach to GR: https://www.amazon.com/dp/0486632822/?tag=pfamazon01-20

 

[Papo1111]

Thank you very, very much, everyone. It really helps a lot.

 

[A.T.]

This small book is inexpensive and would be very interesting for you, given where you are in your physics education right now. See if your local library has a copy, or just buy a copy off of Amazon (or ask for it for your birthday present)

"Thinking Physics" by Lewis Carroll Epstein: https://www.amazon.com/dp/0935218068/?tag=pfamazon01-20

View attachment 239896

And specifically on relativity from the same author:

https://www.amazon.com/dp/093521805X/?tag=pfamazon01-20

 

[Papo1111]

If you change space curvature to space-time curvature, both wormholes and the Alcubeirre warp drive (as previously mentioned by another poster) illustrate that it is possible to travel through space via space-time curvature.

In the context of General relativity, space curvature (as distinct from space-time curvature) depends on the observer, because space and time are intertwined. For instance, in the Schwarzschild metric representing a static, hovering, observer, there is space curvature around a massive body, while around the very same mass, in Painleve coordinates which represent an observer in free-fall, there is no spatial curvature. In both cases, though, the space-time around the black hole is curved.

We can only give answers in the context of General relativity here - or possibly some other peer-reviewed scientific theory of gravity (though other theories are not nearly so well studied). We can't give answers about someone's personal theories - it's up to them to understand their personal theory well enough to be able to make predictions from it, that isn't something we can help with.

Hopefully, however, the answer to the rephrased question (replacing space curvature with space-time curvature) according to General relativity will be satisfcatory.

An interesting question is whether any of the exotic methods for traveling through space that General relativity allows might also allow time travel, since space and time are so closely related in the theory. The answer to that isn't really clear at this point. It's an interesting quesiton, but a bit off-topic.

Well... What kind of time travel? To the future or the past?

If I understand it correctly then time travel to the future is possible. Actually everything that moves is traveling a little bit to the future, even if it is almost unmeasurable.

I don't know about the past tough. But If I'm not mistaken, when you break lightspeed then you should travel to the past. Or at least the formula for time dilation says so. (Yeah I know that you cannot square route a negative number but some calculators will give you the actual number with tis little "i " behind it. I don't really know what does it means tough.

I don't know if you now about Lijun Wang's experiment with laser and cesium gas but it is really interesting. It does include Relativity (or at least I think) too. There also is something with quantum physics there, but I'm totally lost in quantum physics. Here's the link to what I read about it: https://answers.yahoo.com/question/index?qid=20110901183608AANMosc
Please give me your thoughts about it since I'm a great time travel fan.

BTW thanks for the info. I did wanted to write there SPACETIME curvature but then I thought: "Wait, why? I'm not including time dilation or anything." Guess I was mistaken.

 

[jbriggs444]

But If I'm not mistaken, when you break lightspeed then you should travel to the past.

It is a bit more complicated than that. You can Google for "tachyonic antitelephone".

https://en.wikipedia.org/wiki/Tachyonic_antitelephone

 

[Ibix]

If I understand it correctly then time travel to the future is possible. Actually everything that moves is traveling a little bit to the future, even if it is almost unmeasurable.

We all move into the future at one second per second. The key realisation from special relativity is that there is no universal definition of "time", however, so my clock rate according to your definition of time may be a tiny bit slow, and vice versa. It's best to think of this as us traveling in different directions through spacetime. If one of us turns round and comes back, it turns out they've taken a shorter route through spacetime and haven't experienced as much time as the one who didn't turn round. You could describe that as "time travel to the future", but I wouldn't.

I don't know about the past tough. But If I'm not mistaken, when you break lightspeed then you should travel to the past.

As @jbriggs444 says, no.

Or at least the formula for time dilation says so.

It most certainly does not. The assumptions underlying that formula are invalid at and above the speed of light. In fact this is because it's impossible to describe an object traveling faster than light in a coherent way in relativity.

I don't know if you now about Lijun Wang's experiment with laser and cesium gas but it is really interesting.

I don't know about it and yahoo now has way too many cookie options to wade through before I can see it. Do you have a link to a paper?

 

[Papo1111]

I don't know about it and yahoo now has way too many cookie options to wade through before I can see it. Do you have a link to a paper?

[Mentors' note: Copy-paste removed; the link is good enough get to the text]
http://perdurabo10.tripod.com/themindofj...

[Mentors' note: Copy-paste removed; the link is good enough get to the text]
http://news.bbc.co.uk/2/hi/science/natur...

 

[Papo1111]

This also led me to the asumption of that traveling o the past by eceeding speed of light.

 

[Nugatory]

I'll just copy-paste it here:

Sadly, not everything you find on the internet is accurate.

There is a reason why the Physics Forums rules require that we start with real scientific papers, accepted textbooks, and other serious sources instead of reports in the popular press and random web pages... and nonsense like this is that reason. The BBC article is at least well-intentioned, but it was written by a reporter trying to describe something that they themselves do not understand. The other link is pretty much pure crackpottery.

There have been a number of experiments that demonstrate this effect that is described in the popular press as "faster than light", and if you search here you'll find some of the threads in which they are discussed and explained more accurately.

 

[Ibix]

I'll just copy-paste it here:

Please don't - that's a copyright violation. Just the link to somewhere less irritating than yahoo is fine.

http://news.bbc.co.uk/2/hi/science/natur...

In fact, the last paragraphs point out that there's no time travel possible. It's not exactly a trick, but treating it as faster than light is, in some senses, taking the result out of context (the very long excitation time mentioned in passing at the end) in order to generate wow factor.

 

[pervect]

Well... What kind of time travel? To the future or the past?

If I understand it correctly then time travel to the future is possible. Actually everything that moves is traveling a little bit to the future, even if it is almost unmeasurable.

I don't know about the past tough. But If I'm not mistaken, when you break lightspeed then you should travel to the past. Or at least the formula for time dilation says so. (Yeah I know that you cannot square route a negative number but some calculators will give you the actual number with tis little "i " behind it. I don't really know what does it means tough.

I don't know if you now about Lijun Wang's experiment with laser and cesium gas but it is really interesting. It does include Relativity (or at least I think) too. There also is something with quantum physics there, but I'm totally lost in quantum physics. Here's the link to what I read about it: https://answers.yahoo.com/question/index?qid=20110901183608AANMosc
Please give me your thoughts about it since I'm a great time travel fan.

BTW thanks for the info. I did wanted to write there SPACETIME curvature but then I thought: "Wait, why? I'm not including time dilation or anything." Guess I was mistaken.

Much of what I'm referring to is in the Morris, Thorne, Yurtsever paper, "Womrholes, time machines, and the weak energy condition". In particular, the section "conversion of wormholes into time machines. To set up the scenario, one has a pair of wormholes that allow one to traverse space through the wormhole. Then one flies one end of the wormhole around at relativistic speeds, for instance a round-trip journey to a distant star, and back. As is described by the Twin "Paradox", the wormhole mouth that undergoes the round-trip ages less than the one that stays behind. As a result, going through the wormhole pair in one direction allows travel to the future, going through the wormhole pair in the other direction allows travel to the past.

So the answer to your question, "time travel to the past or future" is that wormhole time machines allow both. They connect the past to the future through the wormhole.

This also inspired a popular science treatment by John Cramer in his science fact column "Alternate Views" in Analog, https://www.npl.washington.edu/av/altvw33.html. And a rather grandiose novel by Robert Forward.

There's a lot more to be said on the topic, Kip Thorne's book, "Black Holes and Time Warps", <<amazon link>> is a good book-length popularization. One thing I do want to mention, though - a good keyword for more information about such issues is "Closed timelike curves". That's where most of the paradoxes lie. Some effort has been spent to ask "are CTC's definitely paradoxical". The answer is unclear. "Billiard balls in wormhole spacetimes ...", https://authors.library.caltech.edu/6469/, is one paper that explores some aspects of this - but I don't have a link to a full text version, though I think I've seen one at one time.

As far as the Wang paper goes, I don't believe that the paper demonstrates the existence of a closed, timelike curves (CTC's). If it could be demonstrated that a signal carrying information could be sent faster than light, that would set up the possibility of CTC's, but I don't think the Wang paper goes that far.