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05-23-2016, 03:32 AM #17
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Rivem
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Re: Interstellar Space Travel

Quote:
 Originally Posted by Razako Isn't dark energy sort of the 'anti' force to gravity? It's what's accelerating the expansion of the universe in opposition to gravity.
That's what it looks a bit like, but there's not really any knowledge on how dark energy actually works to expand the universe or how we could even interact with it. Definitely something far from understandable for the time being.

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05-23-2016, 04:34 AM #18
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RedCowboy
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Re: Interstellar Space Travel

The Gravity B project proved the fabric of space/time exists and gravity of large objects such as planets do warp space/time....so we know it is warpable.

Ironically the project ran short on funding and an Arab prince helped fund it....yes my mind was blown too.

Yes cold fusion will change many things, especially our petro dollar that's in trouble, did you notice the big fight between USA/OPEC and the Russia/China conglomerate? They are building a high speed rail from Beijing to Moscow and China bought 51% of Russia's oil fields, they run them and will be competitive in time.

Those low low gas prices were to make it unprofitable for China/Russia as our shale and fracking is cheap, Oh guess who is building a super collider 4 times the size of ours ....Yes China, if they get Cold fusion sustainable first the balance will tip and as they are now part of the international banking system and able to set prices we will watch China/Russia travel the stars, we will be broke, and in debt, possibly fighting the holy wars in our streets....it's like a bad B movie huh?

Chances are sustainable cold fusion will spread quickly, too many greedy spies will sell out, but our control of the oil/energy will be over, maybe we can hitch a ride like we do to the international space station.

p.s. The vast distances between Earth and anywhere is light years, alphacentauri is our closest neighbor and we will need to warp space/time to go anywhere...my question is, will warping space/time slow it's passage for only the space travelers, will they return in a month to an Earth 500 years older? Or is that only for high velocity time dilation where space is not warped with it?

We are just so very far away from anything, it's why we exist, the gamma ray busters are the great sterilizers and only our remote location between two of our galaxies spiral arms protects us.

We will need to control vast amounts of energy such as cold fusion and warp space time to go anywhere except Mars and it's not that special, if there's microbial life or not, is it 3 DNA strand life or like us, yes I want us to go, but to really get out there means we have to stop being here and start being there, we can't rocket there by burning matter and spewing expanding gasses, that's very limited, even the ion drive is too slow, we are talking years and years just to go next door. We must warp the fabric of space time.
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Last edited by RedCowboy; 05-23-2016 at 05:22 AM.

05-23-2016, 05:09 AM #19
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Hap
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Re: Interstellar Space Travel

Speaking of space. Has anyone else tried to take a quick peek at Mars tonight? I completely forgot about until about 10 mins ago when checking my astronomy application on my desktop!

If you didn't know. IIRC until May 30th, Mars will be at it's closest point to Earth in it's orbit. Which means it will be the biggest it can get! If you are trying to look for Mars, try looking toward the Southern Sky and find the Moon. From there, look up and to the right and you should see a bright looking dot. That's Mars! I think... lol

I snapped a picture with my iPhone. Not bad for an iPhone 6 to capture another planet

-Alex
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05-23-2016, 05:24 AM #20
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Rivem
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Re: Interstellar Space Travel

Quote:
 Originally Posted by Hap Speaking of space. Has anyone else tried to take a quick peek at Mars tonight? I completely forgot about until about 10 mins ago when checking my astronomy application on my desktop! If you didn't know. IIRC until May 30th, Mars will be at it's closest point to Earth in it's orbit. Which means it will be the biggest it can get! If you are trying to look for Mars, try looking toward the Southern Sky and find the Moon. From there, look up and to the right and you should see a bright looking dot. That's Mars! I think... lol I snapped a picture with my iPhone. Not bad for an iPhone 6 to capture another planet -Alex
Just brought my telescope back in. Saw the ice caps, and it was great. I've been checking Mars out at least once every week though.

Especially good time to spot it though. It's very red and very bright due to opposition.
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05-23-2016, 05:34 AM #21
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Hap
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Re: Interstellar Space Travel

Quote:
 Originally Posted by Rivem Just brought my telescope back in. Saw the ice caps, and it was great. I've been checking Mars out at least once every week though. Especially good time to spot it though. It's very red and very bright due to opposition.
Sweet! Also, if you are daring, Saturn is right between Mars & the Moon Can't pick that up without a telescope though haha!

I need to get myself one!

-Alex
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"Open your eyes, look within. Are you satisfied with the life you're living?" -Bob Marley
“The universe is a pretty big place. If it's just us, seems like an awful waste of space.” -Carl Sagan
You are important: Pale Blue Dot

05-23-2016, 05:54 AM #22
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Rivem
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Re: Interstellar Space Travel

Quote:
 Originally Posted by Hap Sweet! Also, if you are daring, Saturn is right between Mars & the Moon Can't pick that up without a telescope though haha! I need to get myself one! -Alex
If you're considering one, go to a local star party to try some out. (Good) Telescopes are unfortunately a way bigger money pit than lasers, so you'll definitely want to make a choice you'll be good with for a long time.
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05-23-2016, 02:13 PM #23
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Re: Interstellar Space Travel

No interstellar space travel for humans. Ever. Robotic ships, maybe but I doubt it. Why?
1. Too slow, even if large matter could miraculously approach the speed of light, which it can't....and won't.
2. Requires way, way way too much energy to do this in the span of a human lifetime.
3. "Warp speed" is Star Trek B.S.....might as well be called Bull-Crap speed, at least in this universe. "Bull-Crap factor 4, engage!"
4. Transporters - more complete B.S. Ain't ever going to happen. EVER! And, even it were possible, are you going to step into a machine that kills you by converting you into energy? You might as well let a Lion eat you, let it run 100 miles and then poop you out - there you go, you were just "transported" 100 miles - hope you enjoyed your trip!
5. And, let's say you survive "suspended animation" and make it to another nearby star. Then what? You find a few dead planets orbiting a star; decide to land on one. Oooops, don't have enough energy to get off the cold dead rock. You die. Or, perhaps you make it off the cold dead rock - Oooops, forgot, there isn't anyone to prep your body for suspended animation for the flight back to earth - you die. Or you just die one of a million other different ways.

Sorry to be such a crumudgeon. The laws of physics is why I don't believe we have ever been visited by an alien race. There are probably plenty of intelligent species out there....its just that I don't believe they are any better at breaking the laws of physics than we are.

05-23-2016, 04:36 PM #24
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Pi R Squared
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Re: Interstellar Space Travel

And have we already discovered everything there is to discover? Have we invented everything there is to invent? Do we know everything there is to know? Is there no room left for advancement in science and technology?

Alan
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05-23-2016, 04:59 PM #25
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Razako
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Re: Interstellar Space Travel

Quote:
 Originally Posted by Pi R Squared And have we already discovered everything there is to discover? Have we invented everything there is to invent? Do we know everything there is to know? Is there no room left for advancement in science and technology? Alan
There's still room for advancement, but I feel like we're hitting diminishing returns at this point. We'll need radical new technologies to make much further progress.

It's ultimately gonna depend on whether the rules of physics have any 'wiggle room'. If FTL travel is impossible then we're unlikely to have interstellar space travel in any kind of meaningful way. Even if we were able to develop ships traveling at near light-speed there would be problems. A little spec of dust out in space would hit like a bomb at such speeds. We'd pretty much need to develop 'shielding technology' to protect our starships from space dust.

Anyway, I believe we have some pretty obvious priorities here on Earth before we aim for the stars.
-We need to find a sustainable way to power our civilization. Even if climate change is some kind of hoax, we're still gonna run out of fossil fuels eventually. Fusion power would be IDEAL, but if that's impossible/impractical we could probably make due with a global interconnected solar powered grid.
-We need to fix the overpopulation issue or we're going to destroy the habitability of our home world in a few hundred years. There's no way to sugar coat this one. People just plain need to stop having so many kids. Don't know how to enforce this without some kind of totalitarian global 1 child policy though.
-We need to stop wasting so many resources on war and religious disputes. Just imagine if all the resources dumped into our bloated military were going into a national renewable energy program.

Unless these issues are solved, our civilization will be unlikely to make it another 300-500 years, much less travel to the stars.
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Last edited by Razako; 05-23-2016 at 05:01 PM.

05-23-2016, 05:17 PM #26
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RedCowboy
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Re: Interstellar Space Travel

We have handicapped ourselves, debt is a financial weapon and Barry has done his job well, now it costs more for less, BTW did you hear Barry just lifted a 50 year weapons embargo with Vietnam?

We have wasted so much potential and sadly having the ability to project force worldwide overnight makes it where we don't have to fight.

Sadly we have already been set upon a course and much damage will take time to undo.

I swear I hate it, from riding animals to the moon and 50 years later what have we done.

Supposedly we reach infinite mass at light speed so travel would be sub light speed, and yes we will go no where at that speed, but if we can compress the space in front of us as we travel through it then we circumvent the light speed limit, we know time dilation exists, even out GPS has to account for it, but once we have the knowledge it will be easy, but it's hard to invest in the future when we are falling so far behind.

China is investing in the future, a new super cannel wider than the Panama, next to it even, worlds largest hydro electric dam, our leaders are short sighted and half our citizens don't even have a set of rules, looks like we needed the church after all, I kinda expected it but did not want to accept it, I thought rational logical man can do better without this hokus pokus impediment, but it was protecting us from ourselves.

Our greed is our undoing, that and complacency/apathy.

Hey, maybe China will show off some pics of the places they go.
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Last edited by RedCowboy; 05-23-2016 at 05:20 PM.

05-23-2016, 05:33 PM #27
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vortish
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Re: Interstellar Space Travel

Warp theory is not bs! Two well know physicists have proved that it is possible. Its a matter of folding space. Transporters on that kind of range no but matter transporters are possible the Jet Propulsion Lab has one running its just not perfected yet. Ion engines are capable of reaching right now about a half a c of acceleration at that speed we could reach our nearest neighbor in sixteen to eighteen years. so its not out of the relem of possible
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445 nm 1.6 watt custom needs fixing $50 501b 05-23-2016, 05:41 PM #28  Class 3B Laser Join Date: Mar 2006 Location: Utah Posts: 3,859 Rep Power: 1427 Razako Class 3B Laser Join Date: Mar 2006 Location: Utah Posts: 3,859 Rep Power: 1427 Re: Interstellar Space Travel Quote:  Originally Posted by RedCowboy We have handicapped ourselves, debt is a financial weapon and Barry has done his job well, now it costs more for less, BTW did you hear Barry just lifted a 50 year weapons embargo with Vietnam? We have wasted so much potential and sadly having the ability to project force worldwide overnight makes it where we don't have to fight. Sadly we have already been set upon a course and much damage will take time to undo. I swear I hate it, from riding animals to the moon and 50 years later what have we done. Supposedly we reach infinite mass at light speed so travel would be sub light speed, and yes we will go no where at that speed, but if we can compress the space in front of us as we travel through it then we circumvent the light speed limit, we know time dilation exists, even out GPS has to account for it, but once we have the knowledge it will be easy, but it's hard to invest in the future when we are falling so far behind. China is investing in the future, a new super cannel wider than the Panama, next to it even, worlds largest hydro electric dam, our leaders are short sighted and half our citizens don't even have a set of rules, looks like we needed the church after all, I kinda expected it but did not want to accept it, I thought rational logical man can do better without this hokus pokus impediment, but it was protecting us from ourselves. Our greed is our undoing, that and complacency/apathy. Hey, maybe China will show off some pics of the places they go. Interesting perspective actually. I too sometimes wonder about whether we actually need organized religions for society to function well. Organized religion has pros and cons, but it does seem to provide a 'unifying force' and 'guidance' to some people. Working together to achieve something greater than individual gratifications. Without religion I've seen some people lose their direction in life. They'll just seem to have a 'whatever' attitude about stuff. Is the belief in accountability for our actions in this life necessary to keep society running well? I personally don't know. Possibly it is for some people and not for others. __________________ 700mw 405nm Sanwu Challenger(782mw peak 730ish mw average) Sanwu Spiker Series 3W 445nm 2W O-like 450nm(2.2W average/2.25W peak) and Ebay 450nm THOR M II laser(1600mw average/1700 mw peak) 1.4W Jetlasers PL-E Pro 462nm(average 1490mw) 5.05W 465nm build by AlienLaser and 3.5W 465nm Jetlasers PL-E pro. 50mw 515nm challenger(85mw average) and 5-30mw penlaser 1W 520nm Sanwu Spiker series with beam expander 800mw 532nm Jetlasers PL-E Pro (850mw average, 988 mw peak) and 450mw laserglow Hercules with X10DR beam expander 8mw 561nm project box build(8-9mw average 10 mw peak) 589nm Dragon Lasers Spartan 50(51mw average/70mw peak) 593.5nm 2-5mw CNI penlaser(2-3mw average) 638nm Sanwu Spiker series(860mw average) and 500mw O-like 638nm pointer 639nm Sanwu Silver Series Tribeam(1700mw average/1800mwpeak) 1W 650nm Jetlasers PL-E Pro(1038mw average 1087mw peak) 671nm 100mw Red DPSS labby from LillyElectronics 685nm box pointer with laserlands 15mw module. Meters: Laserbee 3.7W usb LPM 05-23-2016, 05:51 PM #29  Class 1 Laser Join Date: Apr 2016 Location: Southeastern US Posts: 93 Rep Power: 196 Skans Class 1 Laser Join Date: Apr 2016 Location: Southeastern US Posts: 93 Rep Power: 196 Re: Interstellar Space Travel Quote:  Warp theory is not bs! Two well know physicists have proved that it is possible. Its a matter of folding space. First, there is no proof that space is folded in this universe. Second, there is no proof or even a provable theory that space can be mechanically manipulated. Third, even if space could be mechanically manipulated, humans don't have the capability or resources to do it. Fourth, even if space could be mechanically manipulated......by humans, that doesn't mean you could travel any faster through it! Fifth, even if you could somehow punch through folded space, you would in all probability be immediately destroyed. If I draw a dot in the center of a piece of paper and then fold it so that the dot is closer to one of the edges of the paper, did the dot actually travel anywhere in relation to the paper that it is affixed to? No. There is no technology that can cause the dot to travel from the middle of the paper to the edge of the paper without destroying the dot or the paper. Last edited by Skans; 05-23-2016 at 05:52 PM. 05-23-2016, 06:03 PM #30  Class 3B Laser Join Date: May 2013 Location: Snohomish County Washington, US Posts: 3,800 Rep Power: 1086 Pi R Squared Class 3B Laser Join Date: May 2013 Location: Snohomish County Washington, US Posts: 3,800 Rep Power: 1086 Re: Interstellar Space Travel Quote:  Originally Posted by RedCowboy looks like we needed the church after all, I kinda expected it but did not want to accept it, I thought rational logical man can do better without this hokus pokus impediment, but it was protecting us from ourselves. Hokus pokus impediment? This is so God Damn fucking arogant and insulting to 98% of the worlds population that I don't know what to say. I suggest you change your attitude right now. In case you didn't know it, all discussion of religion is supposed to be confined to the religion thread! It has no place in this thread, it is completely off topic. Alan __________________ Keychain 650nm <5mW Quartet 4-in-1 630-680nm <1mW AtlasNova 635nm <5mW MillionAccessories 532nm <5mW broken M462 462nm one of a kind (in progress) PLTB450B 450nm 1913mW G2 lens PL520 520nm 82mW acrylic lens S06J 12X 405nm 590mW G2 lens C6 M140 445nm 1.5W 3 element lens 9mm 445nm with G2 lens in a stainless steel host Radiant Electronics X4 3.7W Laser Power Meter Everyone please post here: Countries of LPF. Where are you? <link> ___________________________________________ The light that shines twice as bright burns half as long. 05-23-2016, 06:05 PM #31  Class 3R Laser Join Date: Feb 2014 Location: Moses Lake Posts: 1,263 Rep Power: 426 vortish Class 3R Laser Join Date: Feb 2014 Location: Moses Lake Posts: 1,263 Rep Power: 426 Re: Interstellar Space Travel 1st question are you a physicist? how do you know that it is not possible? 2nd question. yes currently there is no technology that would allow us to do it. But do you know what will be here in fifty years NO unless your some type of time travelling lunatic. There is proven theory of it is possible. but its is in the far future. Is Warp Speed Possible? : Discovery News Warp speed, Scotty? It may actually be possible... - Science NASA discusses its warp drive research, prepares to create a warp bubble in the lab | ExtremeTech Warp Drive More Possible Than Thought, Scientists Say Is Warp Travel Possible? - Science Questions, from the Naked Scientists NASA EM Drive One Step Closer To Reality: Warp Drive Theoretically Possible, But Don't Hold Your Breath : SCIENCE : Tech Times https://www.nasaspaceflight.com/2015...stic-em-drive/ http://www.nasa.gov/centers/marshall...echnology.html here are links that back up what I am saying. __________________ Eniri ----Peace my brothers [Quote--- Winston Churchill.. I do not have any thing else to give my country other than my blood, toil, sweat, and tears.... 532 nm 5 mw ebay pen 532 nm 30 mw guess 301 ebay laser$ 10
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Last edited by vortish; 05-23-2016 at 08:32 PM.

05-23-2016, 06:17 PM #32
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vortish
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Re: Interstellar Space Travel

The Alcubierre drive or Alcubierre warp drive (or Alcubierre metric, referring to metric tensor) is a speculative idea based on a solution of Einstein's field equations in general relativity as proposed by theoretical physicist Miguel Alcubierre, by which a spacecraft could achieve apparent faster-than-light travel if a configurable energy-density field lower than that of vacuum (that is, negative mass) could be created.

Rather than exceeding the speed of light within a local reference frame, a spacecraft would traverse distances by contracting space in front of it and expanding space behind it, resulting in effective faster-than-light travel. Objects cannot accelerate to the speed of light within normal spacetime; instead, the Alcubierre drive shifts space around an object so that the object would arrive at its destination faster than light would in normal space.

Although the metric proposed by Alcubierre is mathematically valid (in that the proposal is consistent with the Einstein field equations), it may not be physically meaningful, in which case a drive will not be possible. Even if it is physically meaningful, its possibility would not necessarily mean that a drive can be constructed. The proposed mechanism of the Alcubierre drive implies a negative energy density and therefore requires exotic matter. So if exotic matter with the correct properties does not exist then the drive could not be constructed. However, at the close of his original paper Alcubierre argued (following an argument developed by physicists analyzing traversable wormholes that the Casimir vacuum between parallel plates could fulfill the negative-energy requirement for the Alcubierre drive.

Another possible issue is that, although the Alcubierre metric is consistent with Einstein's equations, general relativity does not incorporate quantum mechanics. Some physicists have presented arguments to suggest that a theory of quantum gravity (which would incorporate both theories) would eliminate those solutions in general relativity that allow for backwards time travel (see the chronology protection conjecture) and thus make the Alcubierre drive invalid.

Mathematics of the Alcubierre drive
Using the ADM formalism of general relativity, the spacetime is described by a foliation of space-like hypersurfaces of constant coordinate time t, with the metric taking the following general form:

ds^2 = -\left(\alpha^2- \beta_i \beta^i\right)\,dt^2+2 \beta_i \,dx^i\, dt+ \gamma_{ij}\,dx^i\,dx^j
where

\alpha is the lapse function that gives the interval of proper time between nearby hypersurfaces,
\beta^i is the shift vector that relates the spatial coordinate systems on different hypersurfaces, and
\gamma_{ij} is a positive definite metric on each of the hypersurfaces.
The particular form that Alcubierre studied[2] is defined by:

\alpha=1\,
\beta^x=-v_s(t)f\left(r_s(t)\right)
\beta^y = \beta^z =0 \,\!
\gamma_{ij}=\delta_{ij} \,\!
where

v_s(t)=\frac{dx_s(t)}{dt},
r_s(t)=\sqrt{(x-x_s(t))^2+y^2+z^2},
and

f(r_s)=\frac{\tanh(\sigma (r_s + R))-\tanh(\sigma (r_s - R))}{2 \tanh(\sigma R)},
with arbitrary parameters R > 0 and \sigma > 0. Alcubierre's specific form of the metric can thus be written

ds^2 = \left(v_s(t)^2 f(r_s(t))^2 -1\right)\,dt^2 - 2v_s(t)f(r_s(t))\,dx\,dt +dx^2 + dy^2 + dz^2.
With this particular form of the metric, it can be shown that the energy density measured by observers whose 4-velocity is normal to the hypersurfaces is given by

-\frac{c^4}{8 \pi G} \frac{v_s^2 (y^2+z^2)}{4 g^2 r_s ^2} \left(\frac{df}{dr_s}\right)^2,
where g\! is the determinant of the metric tensor.

Thus, because the energy density is negative, one needs exotic matter to travel faster than the speed of light.[2] The existence of exotic matter is not theoretically ruled out; however, generating and sustaining enough exotic matter to perform feats such as faster-than-light travel (and also to keep open the 'throat' of a wormhole) is thought to be impractical.[citation needed] Low has argued that within the context of general relativity, it is impossible to construct a warp drive in the absence of exotic matter

Physics
For those familiar with the effects of special relativity, such as Lorentz contraction and time dilation, the Alcubierre metric has some apparently peculiar aspects. In particular, Alcubierre has shown that a ship using an Alcubierre drive travels on a free-fall geodesic even while the warp bubble is accelerating: its crew would be in free fall while accelerating without experiencing accelerational g-forces. Enormous tidal forces, however, would be present near the edges of the flat-space volume because of the large space curvature there, but suitable specification of the metric would keep them very small within the volume occupied by the ship.

The original warp-drive metric and simple variants of it happen to have the ADM form, which is often used in discussing the initial-value formulation of general relativity. This may explain the widespread misconception that this spacetime is a solution of the field equation of general relativity.[citation needed] Metrics in ADM form are adapted to a certain family of inertial observers, but these observers are not really physically distinguished from other such families. Alcubierre interpreted his "warp bubble" in terms of a contraction of space ahead of the bubble and an expansion behind, but this interpretation may be misleading because the contraction and expansion actually refers to the relative motion of nearby members of the family of ADM observers.

In general relativity, one often first specifies a plausible distribution of matter and energy, and then finds the geometry of the spacetime associated with it; but it is also possible to run the Einstein field equations in the other direction, first specifying a metric and then finding the energy–momentum tensor associated with it, and this is what Alcubierre did in building his metric. This practice means that the solution can violate various energy conditions and require exotic matter. The need for exotic matter raises questions about whether one can distribute the matter in an initial spacetime that lacks a warp bubble in such a way that the bubble is created at a later time, although some physicists have proposed models of dynamical warp-drive spacetimes in which a warp bubble is formed in a previously flat space. Moreover, according to Serguei Krasnikov, generating a bubble in a previously flat space for a one-way FTL trip requires forcing the exotic matter to move at local faster-than-light speeds, something that would require the existence of tachyons, although Krasnikov also notes that when the spacetime is not flat from the outset, a similar result could be achieved without tachyons by placing in advance some devices along the travel path and programming them to come into operation at preassigned moments and to operate in a preassigned manner. Some suggested methods avoid the problem of tachyonic motion, but would probably generate a naked singularity at the front of the bubble. Allen Everett and Thomas Roman comment that Krasnikov's finding "does not mean that Alcubierre bubbles, if it were possible to create them, could not be used as a means of superluminal travel. It only means that the actions required to change the metric and create the bubble must be taken beforehand by some observer whose forward light cone contains the entire trajectory of the bubble." For example, if one wanted to travel to Deneb (2,600 light years away) and arrive less than 2,600 years in the future according to external clocks, it would be required that someone had already begun work on warping the space from Earth to Deneb at least 2,600 years ago, in which case "A spaceship appropriately located with respect to the bubble trajectory could then choose to enter the bubble, rather like a passenger catching a passing trolley car, and thus make the superluminal journey." Everett and Roman also write that "as Krasnikov points out, causality considerations do not prevent the crew of a spaceship from arranging, by their own actions, to complete a round trip from Earth to a distant star and back in an arbitrarily short time, as measured by clocks on Earth, by altering the metric along the path of their outbound trip."

Alcubierre Warp Drive for Spacetime Travel Significant problems with the metric of this form stem from the fact that all known warp drive spacetimes violate various energy conditions. It is true that certain experimentally verified quantum phenomena, such as the Casimir effect, when described in the context of the quantum field theories, lead to stress-energy tensors which also violate the energy conditions and so one might hope that Alcubierre type warp drives could perhaps be physically realized by clever engineering taking advantage of such quantum effects. However, if certain quantum inequalities conjectured by Ford and Roman hold, then the energy requirements for some warp drives may be absurdly gigantic, e.g. the energy -1067gram equivalent might be required to transport a small spaceship across the Milky Way galaxy. This is orders of magnitude greater than the mass of the universe. Counterarguments to these apparent problems have been offered, but not everyone is convinced they can be overcome.

alcubierre warp drive Chris Van Den Broeck, in 1999, has tried to address the potential issues. By contracting the 3+1 dimensional surface area of the 'bubble' being transported by the drive, while at the same time expanding the 3 dimensional volume contained inside, Van Den Broeck was able to reduce the total energy needed to transport small atoms to less than 3 solar masses. Later, by slightly modifying the Van Den Broeck metric, Krasnikov reduced the necessary total amount of negative energy to a few milligrams.

Krasnikov proposed that, if tachyonic matter could not be found or used, then a solution might be to arrange for masses along the path of the vessel to be set in motion in such a way that the required field was produced. But in this case the Alcubierre Drive vessel is not able to go dashing around the galaxy at will. It is only able to travel routes which, like a railroad, have first been equipped with the necessary infrastructure.

Miguel Alcubierre
Miguel Alcubierre The pilot inside the bubble is causally disconnected with its walls and cannot carry out any action outside the bubble. However, it is necessary to place devices along the route in advance, and since the pilot cannot do this while "in transit", the bubble cannot be used for the first trip to a distant star. In other words, to travel to Vega (which is 26 light-years from the Earth) one first has to arrange everything so that the bubble moving toward Vega with a superluminal velocity would appear and these arrangements will always take more than 26 years.

Coule has argued that schemes such as the one proposed by Alcubierre are not feasible because the matter to be placed on the road beforehand has to be placed at superluminal speed. Thus, according to Coule, an Alcubierre Drive is required in order to build an Alcubierre Drive. Since none have been proven to exist already then the drive is impossible to construct, even if the metric is physically meaningful. Coule argues that an analogous objection will apply to any proposed method of constructing an Alcubierre Drive.
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