How Long Would it Take to Travel to the Nearest Star?

[zgoldsmith23]

It's less encouraging if you actually explore the hypothesis. Tis sort of propulsion would depend on a type of matter that we hav no evidence suggesting that it exists or can exist: matter with a negative mass. Really, it's just a result of the fact that many equations in physics still work if you plug negative numbers into them, but that doesn't mean negative mass is really a meaningful concept.

Additionally, the theoretical power requirements would be .... Well, literally astronomical.

That power requirement would all be devastating to the systems and bodies that were being bypassed along with the particles inside the "stability bubble" (if you will) being shot out after the drive was ceased and probably be extraordinarily high-energy. If I recall, too, the Alcubierre drive struggles from the fact that there's no real way to decelerate safely.

 

[Sherman123]

That power requirement would all be devastating to the systems and bodies that were being bypassed along with the particles inside the "stability bubble" (if you will) being shot out after the drive was ceased and probably be extraordinarily high-energy. If I recall, too, the Alcubierre drive struggles from the fact that there's no real way to decelerate safely.

All true. My position on this is mostly regarding my positivity that the research is being conducted at all and that theories and postulations are even being published. If we are creating a theoretical understanding of these possibilities in 2013 it gives me a great deal of hope of where we might be in 2513 or 3013.

 

[MoSurveyor]

As I understand it, the only situation in which the Alcubierre drive avoids the problem of FTL and causality is if the information (or person) inside the bubble is prohibited from ever leaving the bubble (or interacting causally in any way) at his destination. But such a warpdrive would be useless, and is not the kind of warpdrive implied in these discussions.

If the information or person is allowed to exit the bubble (and interact causally with his destination), then causal violations can be shown to occur in at least some reference frames (not all). In fact, the method of travel is irrelevant, any time information or a person travels from Point A to Point B FTL, there can be causal violations in at least some reference frames.

The Alcubierre metric doesn't provide any answers to these issues of causality or backwards time travel that pop up with FTL travel in SR and GR. It only provides a theoretical mathematical solution to Einstein's field equations that doesn't have the problem of an infinite energy condition; rather, it requires a negative energy condition.

If FTL travel is possible in any way including via a warp drive, we must either (1) reject causality (unlikely, and it would probably render science inconsistent and unworkable) or (2) reject relativity (unlikely, given the overwhelming body of empirical data supporting it). My understanding is that most physicists consider the most likely possibility that quantum effects prevent us from achieving the negative energy densities necessary.

Here are some readings that explain better than I can.

Relativity and FTL Travel: Part IV

Q: Is the Alcubierre warp drive really possible? How close are we to actually building one and going faster than light? | Ask a Mathematician / Ask a Physicist

Faster-than-Lightspeed Time Travel

http://exvacuo.free.fr/div/Sciences...tt - Warp drive and causality - prd950914.pdf

I'm a firm believer in Hawking's Chronology Protection Conjecture. In your first link (Part IV: Faster Than Light Travel), the FTL 'bullet' WAS fired, therefore observer O, for whatever reason, DID NOT stop observer O' from firing the FTL gun. One world, one set of events (regardless of the order experienced by any one person), no paradoxes. While there may be "parallel" universes out there, I do not believe we create them or jump tracks from one to the other by 'making decisions' or 'altering our past'.

 

[JJB3333]

I thought Sol was the closest star?



Problem with traveling fast is mapping a rout. Having some way to scan hundreds of thousands of miles ahead of you is integral to not hitting anything (and dying as a result) when you are traveling thousands of miles per minute.

true but moving that fast would create an incredible amount of heat. If you could redirect that heat into a concentrated burst, you would be able to carve a path through most things

 

[JJB3333]

A question most would like the answer to, and those with even a ballpark idea would like to see hastened.
No Star Trek 'Warp speed' ...alas.

How Long Would it Take to Travel to the Nearest Star?
by IAN O'NEILL

speaking of propulsion, we might as well mention scoop field propulsion.
Bussard ramjet - Wikipedia, the free encyclopedia

 

[the_recruit]

I'm a firm believer in Hawking's Chronology Protection Conjecture. In your first link (Part IV: Faster Than Light Travel), the FTL 'bullet' WAS fired, therefore observer O, for whatever reason, DID NOT stop observer O' from firing the FTL gun. One world, one set of events (regardless of the order experienced by any one person), no paradoxes. While there may be "parallel" universes out there, I do not believe we create them or jump tracks from one to the other by 'making decisions' or 'altering our past'.

Fine, but the simplest answer by far as to what the laws of physics must be so as to preserve the chronology protection conjecture and prevent every such conceivable paradox is simply that the laws of physics do not allow for FTL travel. In fact, that might be the only self-consistent answer.

 

[MoSurveyor]

Fine, but the simplest answer by far as to what the laws of physics must be so as to preserve the chronology protection conjecture and prevent every such conceivable paradox is simply that the laws of physics do not allow for FTL travel. In fact, that might be the only self-consistent answer.

That's not "simple" by any means, more like simplistic. How many times must the paradigms of science, physics in particular, this time, change before we admit how little we know? We're not even sure that gravity isn't FTL as long as LIGO has no results and the graviton is still a myth.

 

[Deuce]

true but moving that fast would create an incredible amount of heat. If you could redirect that heat into a concentrated burst, you would be able to carve a path through most things

Directing heat forward would just slow down the ship. Directing heat aft is essentially what propelled your ship in the first place.

 

[JJB3333]

Directing heat forward would just slow down the ship. Directing heat aft is essentially what propelled your ship in the first place.

true but eliminating obstacles instead of having to plan to go around them would decrease time, possibly making up for the momentary decrease in speed.

 

[Deuce]

true but eliminating obstacles instead of having to plan to go around them would decrease time, possibly making up for the momentary decrease in speed.

I have a suspicion that is mathematically impossible. A sizable object would require an enormous amount of energy to eliminate, energy probably better spent on a minor course correction.

Also, there aren't really "obstacles" in space.

 

[JJB3333]

I have a suspicion that is mathematically impossible. A sizable object would require an enormous amount of energy to eliminate, energy probably better spent on a minor course correction.

Also, there aren't really "obstacles" in space.

haha you ever tried passing through planets, stars, asteroid belts, comets, black holes, etc...?
obstacles in space are rare when you consider the size of the universe, but when you also consider that most of space travel we would accomplish is inter-galactical and that is where most of those obstacles are found.

And yes you are probably right that it would take a lot of power to destroy those obstacles and there would still be a lot of things we couldn't destroy, but if we were able to destroy some small obstacles, it would make for a more direct route.

 

[Deuce]

haha you ever tried passing through planets, stars, asteroid belts, comets, black holes, etc...?
obstacles in space are rare when you consider the size of the universe, but when you also consider that most of space travel we would accomplish is inter-galactical and that is where most of those obstacles are found.

You really have absolutely no concept of just how empty most of space is. The only obstacles you are going to find would be in your departure and destination star systems. You aren't destroying a planet or a large asteroid. It would be far, far less energy intensive to simply go around the object.

And yes you are probably right that it would take a lot of power to destroy those obstacles and there would still be a lot of things we couldn't destroy, but if we were able to destroy some small obstacles, it would make for a more direct route.

Absurd. An obstacle requiring a sizable course correction would never be destroyed. At the speeds involved, you have to completely vaporize the object, because even fragments can put lethal punctures in your ship. It's the sort of thing that might be useful for micrometeors.