# Understanding of wormholes

1. Dec 31, 2005

### sweetvirgogirl

from my understanding of wormholes, you can use a wormhole to build a time machine to go back in past.

However, i think you cant go back in time before the time machine was built... right? or is there a way around?

2. Dec 31, 2005

### Vast

Well, there is a way around. If there was a naturally occurring wormhole in space, you could use that to go further back into the past. If what you mean is, a man made time machine forbids anyone going back further than when the time machine was created?

Of course all this is very speculative, but I’m not sure general relativity rules it out.

3. Dec 31, 2005

### sweetvirgogirl

well ... even if there was a naturally occuring wormhole, i think you can go to future and come back ... i'm not sure how you can go farther back in time

^I'm not tryina argue ... just trying to understand the basic concepts :)

4. Dec 31, 2005

### Vast

What I meant was, if there was a man made time machine created sometime in the year 2300, as you said, you couldn’t use that to go back in time to the year 2000, just say. But if you found a naturally occurring wormhole, which had existed for hundreds of millions of years in some local region of space, then you could use that to go further back in time than the year 2000.

I’ll see what I can find on the net, but I mainly read about this in books over the years. If you’re interested in doing a little reading on the subject yourself, I highly recommend https://www.amazon.com/gp/product/0...02-2159756-6552169?n=507846&s=books&v=glance" by Kip Thorne.

Last edited by a moderator: Apr 21, 2017
5. Dec 31, 2005

### sweetvirgogirl

I disagree ... based on what i know about wormholes ...

man i get confused easily.... so whateva

6. Dec 31, 2005

### Vast

Ok, we have two independent time machines, one man made, and the other a black hole or wormhole naturally existing in space somewhere nearby. The man made one is switched on sometime in the twenty third century, which means one could travel to the future and to the past, but not before the time in which it was switched on. The other black hole or wormhole located in space has existed for hundreds of millions of years, which means you can use that one to travel back in time. There is a problem though. With the naturally occurring wormhole, we would be unable to see where the other end would lead to; we would have no control over where we went.

There are some other means of achieving time travel into the past, such as faster than light travel. Stephen Hawking has a few in http://www.hawking.org.uk/lectures/warps.html" [Broken]

Last edited by a moderator: May 2, 2017
7. Dec 31, 2005

### Vixus

Wait, I want to know something. Does the time-machine move with the user or does the user 'step inside' and get transported to the time-machine in the future? In that case, say the user stepped inside in the year 2000 and wished to travel to the year 3000. What if the time machine was destroyed by accident or otherwise in the year 2500? It's also therefore impossible to go back in time as the machine never existed.

If the machine travelled with the user, then, I have no idea. It would have to be completely self-reliant energy-wise, etc.

How are wormholes created? Are they created spontaneously or gradually? If it was spontaneous the creation process is occurring in the future and past at the same time, depending on where either end of the wormhole is, right? From that moment on the wormhole's ends are fixed in time. So there isn't a limit in terms of when the wormhole was created. The wormhole 'creates' itself with one end already in the past/future.

Wormholes connect black-hole singularities, correct? I'm assuming they connect across time, rather than space:

http://bg.spheredev.net/wh.PNG [Broken]

So was the wormhole created spontaneuosly when the blackhole was created? Then there's no way you can travel further than when the black hole was created as that's the end of the wormhole.

How would one create a time machine anyway? :D

Last edited by a moderator: May 2, 2017
8. Dec 31, 2005

### Staff: Mentor

I'm just an engineer, but I always thought a wormhole simply allowed you to outrun your own light cone.

9. Dec 31, 2005

### Vast

Thorne and Morris detail a scenario in which a wormhole is constructed, so that mouth A is placed in a spaceship and mouth B at the launch pad. The spaceship takes off and travels close to the speed of light for several light years and then comes back to Earth. In this scenario, the wormhole is converted into a time machine, so that stepping through the wormhole would provide faster than light travel which would also mean traveling into the past or future depending which side you were on.
I think the difficulty lies in keeping the wormhole open. Either it remains open for a very short amount of time, or the opening is so small that nothing can pass through. The rest I have no idea.
They should be able to connect both space and time.

Last edited by a moderator: May 2, 2017
10. Dec 31, 2005

### Vast

Wouldn’t that be in the case of traveling faster than light, not necessarily to do with wormholes?

11. Dec 31, 2005

### masudr

Fear not, your humour isn't lost on everyone.

12. Dec 31, 2005

### pervect

Staff Emeritus
Try reading John Cramer's alternate view columns online

http://www.npl.washington.edu/AV/altvw33.html

for the first article he wrote on wormholes,

http://www.npl.washington.edu/AV/

for the index. Cramer is a physicist, but the articles are written for a mass audience (the science fact column of analog) - so you've got reasonable quality, but not a lot of the detailed math (I assume that's a plus in your case?).

I may write a little more later, but right now I have to go.

13. Dec 31, 2005

### robousy

I think the basic ideas can be summarized as follows.

1) To go BACK IN TIME:

you will need,

i) A stable wormhole
ii) One end of the wormhole to be moving at the speed of light - or very close to.

So, you enter the wormhole mouth at ANY time and emerge at the other end (that is traveling close to the speed of light) roughly at the same time the wormhole was constructed.

2) To go FORWARDS IN TIME:

This one is easy.

If you can achieve everything in 1) then it shouldn't be too hard to hire a ship that can travel very close to the speed of light.

Sit in the ship for a few minutes at top speed and when you come back to Earth say a thousand years would have passed. (for example)

14. Dec 31, 2005

### JesseM

The usual idea is that you take one mouth on a round trip at relativistic speeds, and then bring it to rest again relative to the other mouth. Just like in the twin paradox, the two mouths will have aged differently, so this will mean there's a constant time difference between them. That means one trip isn't going to automatically take you back to when the wormhole was created, regardless of when you enter; instead, if you enter one mouth you'll exit the other at some fixed amount of time before you entered (say, 1 hour earlier), and by circling back to the other mouth at this earlier time you can enter it and exit the other mouth at an even earlier time, so by making multiple trips you can eventually get back to the moment when the time difference was first created between the two mouths.
But if you already have a wormhole with a time difference between the two mouths, then if travelling into mouth A and exiting mouth B takes you back in time x seconds, then travelling into mouth B and exiting mouth A takes you forwards in time x seconds. So again, by making multiple trips you can end up as far in the future as you want, provided the wormhole still exists in that time.

15. Dec 31, 2005

### sweetvirgogirl

no .... lol ... i'm a nerd like that

16. Dec 31, 2005

### robousy

...fair enough.

17. Dec 31, 2005

### pervect

Staff Emeritus
A quick note on how wormholes are created: clasically, you do not create wormholes unless you already have a time machine.

(I believe this is mentioned in Thorne's book)
https://www.amazon.com/gp/product/0393312763/103-6964616-2544669?v=glance&n=283155

I can't find the exact reference unless I find my copy of the book :-)

However, some theories have wormholes being spontaneously created on very small scales (the 'quantum foam' model), and it has been suggested that one of these wormholes could be "captured" and "tamed" by a sufficiently advanced civilization (i.e. not us).

Once you have a wormhole, it can be turned into a time machine as described by Jesse, simply by accelerating one end of the wormhole to relativistic velocities.

Many physicists including Hawking believe that the wormhole might "self-destruct" when it is turned into a time machine, due to quantum vacuum fluctuations building up towards infinity in the throat of the wormhole, at the instant it becomes a time machine. Do a google for "Chronlogy protection conjecture".

http://scienceworld.wolfram.com/physics/ChronologyProtectionConjecture.html

is good as far as it goes, but it doesn't go very far. This is also covered in Thorne's book (the one that I can't find the copy of).

Last edited by a moderator: Apr 21, 2017
18. Jan 1, 2006

### -Job-

Doesn't time travel go against preservation of matter/energy? If someone disappears into the past then there'll less matter around. Does anything come out of the past to make up for this?
On the other hand, if we consider the 4D universe with time as the 4th dimension, then matter/energy are distributed throughout the 4 dimensions and if some body at x1, y1, z1, t1 jumps to x1, y1, z1, t2 then from a 4D perspective the universe still has the same amount of matter/energy, it just has been relocated.

19. Jan 1, 2006

### sweetvirgogirl

man... can i include whatever you wrote above in my paper on time travel?

20. Jan 1, 2006

### -Job-

Sure, no problem, i'm quoted all the time.