Not sure if this was already posted, but according to GR it is possible to travel faster than light ‘normally’ does, meaning we could travel to Alpha Centuri in about a couple of weeks.
It is done by expanding the space-time behind the craft and at the same time compressing the space-time in front of the craft:
bourke said:
NASA’s Warp DriveNot sure if this was already posted, but according to GR it is possible to travel faster than light ‘normally’ does, meaning we could travel to Alpha Centuri in about a couple of weeks.
It is done by expanding the space-time behind the craft and at the same time compressing the space-time in front of the craft:
If i understand correctly, it needs a chunk of ‘negative mass’.
So, all we have to do is find a good sized hunk of this substance, which may or may not exist.
bourke said:
Alpha Centuri
Not many tourist destinations there though…. would be a bugger if the engine failed to start for the return journey…
“Hi, yes you’re probably not going to believe this but…”
RACV call desk: “Try me, I’ve heard them all!”
“My friend appears to have broken down out of mobile range…”
RACV: “What’s their current location… GPS coords if you have them…”
“Somehow I don’t think you could triangulate using GPS satellites from Alpha Centauri!” ;-)
bourke said:
bourke said:Alpha Centuri
Sorry, I mean Alpha Centauri…Not many tourist destinations there though…. would be a bugger if the engine failed to start for the return journey…
“Hi, yes you’re probably not going to believe this but…”
RACV call desk: “Try me, I’ve heard them all!”
“My friend appears to have broken down out of mobile range…”
RACV: “What’s their current location… GPS coords if you have them…”
“Somehow I don’t think you could triangulate using GPS satellites from Alpha Centauri!” ;-)
You called the wrong folks. RACQ would get there! ;)
“Negative mass” sounds like it is on the wrong side of plausability.
It is done by expanding the space-time behind the craft and at the same time compressing the space-time in front of the craft:
Step1. Expand the space time behind the craft
Step2. Compress the space time in front of the craft
Step3. ?????
Step4. Profit!!!
Riff-in-Thyme said:
“Negative mass” sounds like it is on the wrong side of plausability.
I don’t believe that’s the official NASA terminology!
bourke said:
Riff-in-Thyme said:
“Negative mass” sounds like it is on the wrong side of plausability.
I don’t believe that’s the official NASA terminology!
I don’t work for NASA!
it’ll be exotic matter or energy.
Boris said:
it’ll be exotic matter or energy.
The DE observations suggest a “negative mass” energy form, but I still haven’t seen any reason these would represent an unidentified energy source rather than the global effects of standard physics that has yet to be identified.
bourke said:
NASA’s Warp DriveNot sure if this was already posted, but according to GR it is possible to travel faster than light ‘normally’ does, meaning we could travel to Alpha Centuri in about a couple of weeks.
It is done by expanding the space-time behind the craft and at the same time compressing the space-time in front of the craft:
This has be discussed before on SSSF. It does require a negative mass to exist. The problem is that separating macroscopic quantities of positive and negative mass from nothing may violate the second law of thermodynamics.
Somehow I don’t think you could triangulate using GPS satellites from Alpha Centauri!”
—————————————————-
Sure you can, but it may have a large margin of error over that sort of distance.
Stealth said:
Somehow I don’t think you could triangulate using GPS satellites from Alpha Centauri!”
—————————————————-
Sure you can, but it may have a large margin of error over that sort of distance.
I think you probably could, but not with the satellite-based GPS we presently use. There are more than 1500 known pulsars, each with a unique period (which makes identification possible). If our spaceship were equipped with a radiotelescope for detecting and identifying pulsars, we could use the known locations of what we detect to triangulate our position, potentially with at least as much accuracy as satellite-based GPS.
As I understand pulsars, they only send out a radio signal along the axis of their spin, and it is only when this beam points directly at us do we get a pulse. The axis precesses so the beam wobbles around in a cone shape and we only see it pulse as that beam passes over us. Therefore once you get any significant distance from Earth, the pulsar wouldn’t pulse at you any more.
Kingy said:
As I understand pulsars, they only send out a radio signal along the axis of their spin, and it is only when this beam points directly at us do we get a pulse. The axis precesses so the beam wobbles around in a cone shape and we only see it pulse as that beam passes over us. Therefore once you get any significant distance from Earth, the pulsar wouldn’t pulse at you any more.
Close. The beam comes out of the magnetic polar axis, which is offset from the spin axis, much as Earth’s magnetic poles are offset from the spin poles.
See http://en.wikipedia.org/wiki/Pulsar#Formation
KJW said:
This has be discussed before on SSSF. It does require a negative mass to exist. The problem is that separating macroscopic quantities of positive and negative mass from nothing may violate the second law of thermodynamics.
Yes. I agree with that. The discussion on SSSF was before the old forum closed so has probably been lost.
mollwollfumble said:
KJW said:
This has be discussed before on SSSF. It does require a negative mass to exist. The problem is that separating macroscopic quantities of positive and negative mass from nothing may violate the second law of thermodynamics.
Yes. I agree with that. The discussion on SSSF was before the old forum closed so has probably been lost.
And I have some archives created automatically by my home-made forum browser, but they don’t go back very far. I’ll see if I can find an Alcubierre Drive thread…
From: ElvisRieu ® At: 15/03/2012 6:11:04 PM
Subject: Alcubierre Warp drive Theoretical Outcomes. post id: 5415530
http://www2b.abc.net.au/science/k2/stn/newposts/5415/post5415537.shtm
The annihilating effects of space travel
March 12, 2012
Long distance space travel could create the ultimate ‘killer entrance’, devastating your destination and anything around the arriving spacecraft, according to calculations by Professor Geraint Lewis and two honours students from the University of Sydney.
The University of Sydney team is the first to publish on the effects of theoretical space travel using an Alcubierre warp drive, in the leading journal of the American Physical Society, Physical Review D.
The Alcubierre warp drive is a theoretical tool that would allow spacecraft to travel long distances in space rapidly by deforming the space-time continuum in a bubble around the spaceship.
Miguel Alcubierre, a Mexican physicist, proposed this warp drive in 1994 as a way to travel faster than light, overcoming the limit on particles travelling at such speeds posed by Einstein’s theory of special relativity.
“When the spacecraft decelerates to stop at its destination, the particles collected at the front of the spacecraft are released with such high-energy that they would destroy anything they came in contact with. During the journey the particles picked up and included inside the bubble could threaten the safety of people travelling in the spacecraft,” said Professor Geraint Lews from the School of Physics.
Brendan McMonigal and Philip O’Byrne, who completed their Bachelor of Science with Honours in Physics in 2011 and 2010 respectively, both worked with Professor Lewis, their supervisor.
“It sounds like it’s straight from science fiction, and in a way it is, as the Alcubierre warp drive is a theoretical solution to the problem of travelling the huge distances in space in a reasonable amount of time,” said Professor Lewis. “But unlike science fiction, the Alcubierre warp drive completely obeys Einstein’s general theory of relativity.”
“All innovations start with theory, however, so these calculations contribute to our understanding of how such speeds could be achieved. Our team decided to consider what would happen to particles and radiation that a spacecraft, travelling in a bubble created by the Alcubierre warp drive, would come across as it travelled through space,” explained Professor Lewis.
“What we’ve shown is that when this spacecraft decelerated to arrive at its destination, it would release high energy particles which would destroy anything near the spacecraft’s landing spot.”
While scientists have examined how it’s theoretically possible to create a bubble around a spacecraft with the Alcubierre warp drive compressing space-time in front of the bubble and expanding it behind the bubble, there has been little consideration of how this high-speed bubble would interact with particles of matter and light.
“Our calculations show that particles that come in contact with the warp bubble can get caught up and congregate in front of the spacecraft, and some particles even enter the warp bubble,” said Professor Lewis.
Brendan McMonigal, one of the honours students working on the research, said, “Interestingly, the energy burst released upon arriving at the destination does not have an upper limit. You can just keep on traveling for longer and longer distances and the energy that will be released will continue to increase – one of the odd effects of General Relativity.”
“Even for very short journeys the energy released is so large that you would completely obliterate anything in front of you,” said Brendan.
“It seems that human exploration of the universe will have to wait until we’ve worked out how to avoid the destructive deceleration of a spacecraft in an Alcubierre warp drive bubble.”
While the study may seem like a fun theoretical consideration, exploring the implications of Einstein’s theory of relativity is significant and has all sorts of practical uses, such as relativity correctors for GPS systems, found in virtually all smartphones, that correct for the time difference between the ground and satellite.
Provided by University of Sydney
http://www.physorg.com/news/2012-03-annihilating-effects-space.html
From: ElvisRieu ® At: 15/03/2012 6:30:19 PM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5415539
http://www2b.abc.net.au/science/k2/stn/newposts/5415/post5415546.shtm
The possibilities for FTL travel or communication implicit in the Alcubierre drive raise the possibility of causality violations and “timelike loops”, i.e., back-in-time communication and time travel. Alcubierre points out that his metric contains no such closed causal loops, and so is free of their paradoxes. However, he speculates that it would probably be possible to construct a metric similar to the one he presented which would contain such loops.
A scheme for converting FTL signaling to back-in-time signaling requires some gymnastics with moving reference frames to invert the time sequence of the “send” event and the “receive” event in a signal transmission. I described such a scheme in a recent column on quantum tunneling and FTL signaling . In the case of the` Alcubierre drive, this would probably require either externally moving the warp generating mechanism at near lightspeed velocities or embedding one warp within the flat-space region of another.
The implications of the Alcubierre warp drive for science fiction are fairly clear. If the theoretical and engineering problems outlined above could be overcome, we would have FTL travel, fully consistent with general relativity, that is reminiscent of the warp drives of the good old-time space operas. Remember, however, that using such a drive would undoubtedly require the manipulation of planet-scale quantities of energy (positive or negative). The user would also have to be very careful to avoid the tidal forces of the distorted-space region at the edges of the flat-space region containing the ship.
And there is also the question of writing the environmental impact statement. What would happen to external objects (space dust, rocks, other ships, asteroids, planets, …) that happened to lie in the path of an Alcubierre ship and entered the region of distorted space-time at the leading edge of the warp, where space is rapidly being collapsed? The nuclei of any matter transiting that region would first experience enormous compressional forces, probably form a quark-gluon plasma reminiscent of the first microsecond of the Big Bang, and then explode in a flood of pi mesons and other fundamental particles when the compression forces were released, stealing energy from the warp field in the process.
A ship traveling in an Alcubierre space warp should be equipped with plenty of radiation shielding. Perhaps that is not a problem, since the equations for the metric and the energy density of the warp do not seem to depend on how much mass is placed in the flat-space region which is given an FTL velocity.
http://www.npl.washington.edu/AV/altvw81.html
The tale end of the link:
http://www.npl.washington.edu/AV/altvw81.html
From: csyrony ® At: 16/03/2012 8:18:40 AM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5415926
http://www2b.abc.net.au/science/k2/stn/newposts/5415/post5415933.shtm
> The Alcubierre warp drive is a theoretical tool that would allow spacecraft to travel long distances in space rapidly by deforming the space-time continuum in a bubble around the spaceship.
Of course, it does not and cannot exist. So unintended consequences of stopping are hardly a worry. Problems of going from faster than light to slower than light were known in science fiction at least as early as 1954 in “Children of the Lens” wherein it is said that “There seemed to be a theoretical possibility, since the mass would instantaneously become some higher order of infinity, that all the matter in normal space would coalesce with it in zero time; but Mentor had assured Kit that operators would come into effect to prevent such an occurrence, and that untoward effects would be limited to a radius of ten or fifteen parsecs.”
From: The Rev Dodgson (Eng Sci) At: 16/03/2012 8:23:38 AM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5415927
http://www2b.abc.net.au/science/k2/stn/newposts/5415/post5415934.shtm
>>
Of course, it does not and cannot exist.
<<
Are you saying it is not even possible in principle? If so, why?
>>
So unintended consequences of stopping are hardly a worry. Problems of going from faster than light to slower than light were known in science fiction at least as early as 1954 in “Children of the Lens” wherein it is said that “There seemed to be a theoretical possibility, since the mass would instantaneously become some higher order of infinity, that all the matter in normal space would coalesce with it in zero time; but Mentor had assured Kit that operators would come into effect to prevent such an occurrence, and that untoward effects would be limited to a radius of ten or fifteen parsecs.”
<<
But did EE Smith actually do the numbers, or was he just making things up?
From: Eric the Bolt ® At: 16/03/2012 10:12:53 AM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5415967
http://www2b.abc.net.au/science/k2/stn/newposts/5415/post5415974.shtm
ee smith wrote that in 1954, Alcubierre came up with the warp drive theory in 1994.
ee smith was a food engineer specialising in doughnut and pastry mixes. (wiki)
i doubt he did the maths. maybe he though of boats stopping and the wave that is pushed forwards when they do.
dunno.
From: Eric the Bolt ® At: 16/03/2012 10:27:35 AM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5415973
http://www2b.abc.net.au/science/k2/stn/newposts/5415/post5415980.shtm
>>Dodging the energy burst
The findings spell bad news for anybody at the warp drive destination. But could the friendly fire of the warp drive be avoided by aiming to one side of your destination? Lewis said further research of the problem in 3-D is needed before that question can be answered.
“We didn’t look at the full 3-D effect of the bubble, so we don’t know if when you stop the drive if it sprays off particles in all directions or if it’s just a very finely collimated beam, but we do know it will throw off beam of high-energy particles,” said Lewis. “So we don’t know how much to the left or the right you need to stand to be safe!”<<
http://www.cosmosmagazine.com/news/5395/warp-speed-visitors-make-unwelcome-guests?page=0%2C1
From: ElvisRieu ® At: 16/03/2012 11:38:45 AM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5416034
http://www2b.abc.net.au/science/k2/stn/newposts/5416/post5416041.shtm
Of course, it does not and cannot exist.
“”“”“”“”“”“”“”“”“”“”“”
I disagree…Of course it won’t be easy, but then it isn’t against the spirit of SR/GR, and of course no one has put a time frame on it.
From: Cymek ® At: 16/03/2012 11:41:04 AM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5416035
http://www2b.abc.net.au/science/k2/stn/newposts/5416/post5416042.shtm
Maybe the warp bubble could be modified to create a bow wake and push all these particles away from the front of ship and leave a trail behind it
From: Peak Warming Man ® At: 16/03/2012 11:42:34 AM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5416039
http://www2b.abc.net.au/science/k2/stn/newposts/5416/post5416046.shtm
One day we might see Zarky and BC sitting in their water powered warp drive landrover being cheered and clapped by the other inmates.
From: ElvisRieu ® At: 16/03/2012 12:51:07 PM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5416077
http://www2b.abc.net.au/science/k2/stn/newposts/5416/post5416084.shtm
One day we might see Zarky and BC sitting in their water powered warp drive landrover being cheered and clapped by the other inmates.
“”“”“”“”“”“”“”“”“”“”“”“
They need you in chat young fella, C’mon now, do us all a favour OK?
From: ElvisRieu ® At: 16/03/2012 1:43:40 PM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5416121
http://www2b.abc.net.au/science/k2/stn/newposts/5416/post5416128.shtm
It’s worth noting despite the usual derisive rantings two posts above, that NASA has JPL specifically put together to examine alternate propulsion methods, including warp drive, worm holes and other means, which at this stage only exist in the realms of sci/fi.
And as I said earlier, doesn’t contravene GR.
From: ElvisRieu ® At: 16/03/2012 1:45:43 PM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5416122
http://www2b.abc.net.au/science/k2/stn/newposts/5416/post5416129.shtm
Miguel Alcubierre Moya (born 1964, Mexico City) is a Mexican theoretical physicist. He obtained a degree in physics, and a Master of Science in theoretical physics at the School of Science of Universidad Nacional Autónoma de México (UNAM).
At the end of 1990, Alcubierre moved to Wales to attend graduate school at the University of Wales, Cardiff, receiving his doctorate through study of numerical general relativity. After 1996 he worked at the Max Planck Institute for Gravitational Physics in Potsdam, Germany, developing new numerical techniques used in the description of black holes. Since 2002, he has worked at the Nuclear Sciences Institute of the National Autonomous University of Mexico (UNAM), where he conducts research in numerical relativity, employing computers to formulate and solve the physical equations first proposed by Albert Einstein. The solitary wave solutions proposed by Alcubierre for the Einsteinian field equations may possibly prove general relativity consistent with the experimentally verified non-locality of quantum mechanics. This work militates against the idea that quantum non-locality would ultimately require abandoning the mathematical structure of general relativity.
Alcubierre is best known for the proposal of “The Warp Drive: Hyper-fast travel within general relativity” which appeared in the science journal Classical and Quantum Gravity. In this, he describes the Alcubierre drive, a theoretical means of traveling faster than light that does not violate the physical principle that nothing can locally travel faster than light. In this paper, he constructed a model that might transport a volume of flat space inside a “bubble” of curved space. This bubble is driven forward by a local expansion of space-time behind it, and an opposite contraction in front of it, so that theoretically a spaceship would be placed in motion by forces generated in the change made by space-time.
http://en.wikipedia.org/wiki/Miguel_Alcubierre
From: Cymek ® At: 16/03/2012 1:47:59 PM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5416124
http://www2b.abc.net.au/science/k2/stn/newposts/5416/post5416131.shtm
I think most scifi shows have both FTL engines and slower than light engines which I find interesting as obviously they work on completely different principles
From: The Missing Link ® At: 17/03/2012 6:37:44 AM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5417004
http://www2b.abc.net.au/science/k2/stn/newposts/5417/post5417011.shtm
>>>>It’s worth noting despite the usual derisive rantings two posts above,
what derisive rantings?
From: KJW (Maths) At: 17/03/2012 7:27:04 AM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5417013
http://www2b.abc.net.au/science/k2/stn/newposts/5417/post5417020.shtm
<Q>
Of course, it does not and cannot exist.
“”“”“”“”“”“”“”“”“”“”“”
I disagree…Of course it won’t be easy, but then it isn’t against the spirit of SR/GR, and of course no one has put a time frame on it.
</Q><Q>
And as I said earlier, doesn’t contravene GR.
</Q>
Have you read the Wikipedia article about the Alcubierre drive?
http://en.wikipedia.org/wiki/Alcubierre_drive
As far as not contravening GR is concerned, the Alcubierre drive requires “exotic matter” that violates energy conditions. Just because a metric can be constructed, it doesn’t mean that the spacetime can be physically realised. Also, quoting Wikipedia:
“The need for exotic matter leads to questions about whether it is actually possible to find a way to distribute the matter in an initial spacetime which lacks a “warp bubble” in such a way that the bubble will be created at a later time.”
Furthermore, even if travelling in the bubble moving superluminally doesn’t violate relativity, moving into or out from the bubble might.
From: ElvisRieu ® At: 17/03/2012 7:50:19 AM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5417025
http://www2b.abc.net.au/science/k2/stn/newposts/5417/post5417032.shtm
>It’s worth noting despite the usual derisive rantings two posts above,
what derisive rantings?
“”“”“”“”“”“”“”“”“”“”“”“”“
It’s been removed…Just the usual buffoonery from a particular corner.
“”“”“”“”“”“”“”“”“”“”“”“”“”
Have you read the Wikipedia article about the Alcubierre drive?
“”“”“”“”“
There are those that say it cannot be done KJW I realise that, but we also have many others who while realising it will be difficult and that we probably wont have the technology for the foreseeable future it may still be achieved.
JPL is working on many methods of alternate propulsion methods. including many means of close to or FTL travel.
No one is underestimating the difficulty of achieving it
From: Postpocalypse ® At: 17/03/2012 11:08:36 AM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5417189
http://www2b.abc.net.au/science/k2/stn/newposts/5417/post5417196.shtm
I found this amusing. This sounds like the type of system I was trying to understand when I started researching. I think ’94 was even about when I started getting into it. Interesting article. Excellent scenario for developing theory.
From: ElvisRieu ® At: 17/03/2012 11:26:16 AM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5417204
http://www2b.abc.net.au/science/k2/stn/newposts/5417/post5417211.shtm
Glad you liked it Postapocylipse…
As I said, NASA’s JPL are already doing reserach into many areas of alternate propulsion methods,
From: KJW (Maths) At: 17/03/2012 7:37:32 PM
Subject: re: Alcubierre Warp drive Theoretical Outcomes. post id: 5417725
http://www2b.abc.net.au/science/k2/stn/newposts/5417/post5417732.shtm
<Q>
There are those that say it cannot be done KJW I realise that, but we also have many others who while realising it will be difficult and that we probably wont have the technology for the foreseeable future it may still be achieved.
JPL is working on many methods of alternate propulsion methods. including many means of close to or FTL travel.
No one is underestimating the difficulty of achieving it
</Q>
As I said, the Alcubierre drive violates energy conditions, which means that to say it doesn’t contravene general relativity is very much a stretch. Violation of energy conditions is not just a technological limitation, but is very likely to be a theoretical limitation once we’ve unified all the major strands of physics.
<Q>
maybe even for a couple of hundred years
</Q>
One can’t put any sort of timeframe on this. We are no closer to having a source of exotic matter than Newton, Aristotle, or even Tutankhamun.
When the spacecraft decelerates to stop at its destination, the particles collected at the front of the spacecraft are released with such high-energy that they would destroy anything they came in contact with. During the journey the particles picked up and included inside the bubble could threaten the safety of people travelling in the spacecraft,” said Professor Geraint Lews from the School of Physics.
===
so why don’t you just suck all these spare particles up inside the bubble and attach them to the ship in some way?
wookiemeister said:
When the spacecraft decelerates to stop at its destination, the particles collected at the front of the spacecraft are released with such high-energy that they would destroy anything they came in contact with. During the journey the particles picked up and included inside the bubble could threaten the safety of people travelling in the spacecraft,” said Professor Geraint Lews from the School of Physics.
===so why don’t you just suck all these spare particles up inside the bubble and attach them to the ship in some way?
less dramatic?
>During the journey the particles picked up and included inside the bubble could threaten the safety of people travelling in the spacecraft,” said Professor Geraint Lews from the School of Physics.
Bloody astrologers.
sibeen said:
:-)
>During the journey the particles picked up and included inside the bubble could threaten the safety of people travelling in the spacecraft,” said Professor Geraint Lews from the School of Physics.Bloody astrologers.
There was a young lady from Bright,
Who could travel much faster than light,
She left one day,
In a relative way,
And arrived the previous night.