The absurdity of faster-than-light travel
The Alcubierre Drive
Miguel Alcubierre published a paper in 1994 that demonstrated by using the field equations of general relativity that a bubble of flat spacetime can
move at an effective speed faster than the speed of light.
Unfortunately, there are numerous problems that appear to be show-stoppers to the Alcubierre Drive. For one, the paper only states how to keep the
bubble moving once it has already formed, but does not show at all how to generate the bubble. Secondly, part of the warp bubble wall is causally
disconnected from the interior of the bubble since we have an effective velocity faster than the speed of light. This means it is impossible for
someone inside the ship to send signals to control the bubble. Thirdly, according to a
paper published by
cosmologist Stefano Finazzi, temperatures would soar to 10^32 kelvin inside the bubble. That's 26 orders of magnitude hotter than the core of the
sun.
Even if a sufficiently advanced civilization could solve all of these engineering problems, the major hurdle is the energy requirements. The early
calculations showed it required an amount of energy that was greater than all that existed in the known universe. This number was brought down by
subsequent calculations to the mass-energy equivalence of Jupiter, and finally recently, the mass-energy equivalence of the voyaegeur space probe.
Only problem is that this is not ordinary energy that gravitates as we would expect. Rather, it is negative energy. Other than negligible effects such
as the Casimir effect and the energy responsible for the accelerated expansion of the universe, there is no evidence of a macroscopic instance of this
phenomena that can be engineered. The most advanced and accepted examples of quantum field theory, which is by far the most successful model of nature
devised by mankind, does not include the existence of negative mass. Thus, the warp drive is looking like it will always remain in science fiction.
Wormholes
What about wormholes, you might retort? Another golden staple of science-fiction that does seem to be a theoretically sound concept. The idea
originated in the 1930s with Albert Einstein and Nathan Rosen. It was a theoretical curiosity and it wasn't until almost 60 years later that Kip
Thorne and his graduate student Mike Morris revived the idea as a method of space travel. Like the warp-drive, it is riddled with problems that seem
to be insurmountable. Firstly, papers based on the model used by Kip Thorne show it to be inherently unstable and would collapse as soon as it was
opened. The only way to stabilize the wormhole is through the constant supply of the wormhole, which brings us back to the warp-drive. Secondly, the
mouths of the wormhole must be transported to the destination in order to be accessed and thus requires at least 1 trip via subluminal travel to the
destination. So, ET must have at least been to our system once using subluminal methods and avoided complete detection. Thirdly, there is as of now no
evidence that wormholes exist in nature and has so far never been observed. Fourthly, as Einstein showed in general relativity that space and time are
intricately connected, distorting space in such a way would also simultaneously distort time as well. This means when you enter the hypothetical
wormhole, there is no guarantee you won't emerge 300 billion years into the future or 10 million years into the past. Effective faster than light
travel means you can also create time-travel, which brings with it the problem of all the time-travel paradoxes that are yet to be resolved. There is
no known way to divorce space and time in such a way that you would obey causality as you pass through.
Lastly, both methods require the existence of anti-gravity and if it can be utilized for practical purposes. This doesn't seem controversial, but it
is in direct opposition to one of the two greatest models of nature to date: general relativity.
Einstein Speaks
Albert Einstein published the formidable general theory of relativity in 1916, which replaced classical Newtonian gravity as the supreme model for
gravity. It was a triumph for general relativity that it predicted the nature of the bending of light in the 1919 eclipse, a phenomena that could not
be explained via Newtonian gravity. Almost all of its predictions have been verified to many decimal places. In this model of nature, gravity is not
considered a force, but rather the byproduct of the bending of spacetime by mass-energy.
In general relativity, seeing as gravity is the positive geometry of the curving of spacetime, anti-gravity requires "negative geometry". Seeing as
such a thing is absurd under this model, general relativity therefore prohibits the existence of anti-gravity. Now, in all fairness, there are
some models beyond the standard model of particle physics that require the gravitational force to be mediated by some particle known as a
"graviton". This is in direct contradiction of the classical interpretations of gravity as a byproduct of the curving of spacetime in general
relativity. It is unknown whether anti-gravity can be ruled out completely under such models, but seeing as such effects would effectively be on
microscopic scales that could never be used for any practical application such as space travel and that these models must reduce to the predictions of
general relativity for macroscopic gravity, anti-gravity is therefore completely impractical at best and outright impossible at worst.
Due to this fundamental reason alone, it seems both wormholes and warp drives are out of the question.
edit on 18-3-2013 by Diablos because:
(no reason given)
edit on 18-3-2013 by Diablos because: (no reason given)