I should preface this article by pointing out that I do not know everything, ever and that I am working on the knowledge I have collected and can interpret from the given experiences I have been exposed to through both personal exploration and accidental exposure. There! That should fend-off the Babylon 5 fans! ;)
There are actually many sci-fi misconceptions about space and many tropes used regarding this part our understanding but I'm only going to focus on one: warping space.
Space as we refer to it is (according to our current limited understanding) actually a continuous mesh of physicality, energy and time - whatever that may actually turn out to be! Most people popularly call this construction Spacetime.
The important thing to note about spacetime is that no constituent of this can be separated completely from the rest of it. Much as particle-wave duality has no separation - i.e. everything is a particle and a waveform, including macro objects like humans, trees, planets etc. - spacetime is its own thing. It is all around us, within us and part of us. In many ways, George Lucas was correct about The Force: including that we can affect it.
Don't get any hasty ideas now because we can't affect it in any 'conscious' manner. We affect it by 'being'. Simply existing in our own configuration, our own mass has an imprint and waveform on the very fabric of spacetime. It's a very small imprint but it exists nonetheless.
So taking these concepts further lets get onto the topic at hand: warping space.
Usually warping space is used as an idea of how to manipulate the universe around us in order to get around that pesky limitation of the speed of light. In the 1930's-1950s science fiction authors came up with a very convenient plot device - hyperspace. Hyperspace is not a warping of space but is actually entering into another, smaller (or longer, depending on your point of view) dimension of reality, allowing an object to travel outside the limitations of the physics of spacetime. However, there was usually an energy barrier needed in order to achieve this 'state'. (The 1961 book, "Time is the simplest thing", is one of the exceptions)
Later on, in the 1940s-1950s Asimov, among others, started mentioning 'space-warp' engines in their fiction and thus the warp drive was born. There may be earlier examples but, accordingly, that era of literature tends to be less well available on the internet and also less critiqued. Obviously, to any semi-literate or TV-conscious sci-fi aficionado, the concept of the warp drive was popularised by Star Trek and entered into the mainstream consciousness freely from the 1960s-onwards.
What is interesting is that this concept of travelling faster than light, in order to get somewhere to move a story along or even within a character's own lifetime, came along well before the sound barrier was a commonly understood problem. The time problem of travel to distant places precluded the notion of limitation of speed within a given fluid. Mach speed and supersonic, both common terms that you may assume came before the concept of a warp drive actually came after (some time around world war II). This is, of course, ignoring the concept of the speed of light being limited by spacetime because it encompasses physical materials, much like how the speed of light is different depending on whether it is travelling through the vacuum of outer space or a crystal prism... or even water. However, general relativity limits the speed of light in a given material and this theory has no concept of being able to overcome those limitations - unlike the movement of a physical object past the speed of sound.
Asymptotically, the concept of travelling through a spatial warp (often referred to as a wormhole) was also developed quite well after Einstein's theories were taken on board in the physics world. In 1921, mathematician Hermann Weyl derived mathematical situations where a physical bridge in spacetime could possibly occur but it was John Archibald Wheeler in 1957 who coined the term 'Wormhole' and went into further theoretical detail.
While wormholes are a form of warp travel, and thus warping spacetime, they are not considered a warp drive unless the drive itself is creating a wormhole. This sort of representation is usually a lesser-used convention of the sci-fi medium and is usually used in contexts of lesser technologically-advanced species whereby they have sent out 'reconnaissance' vessels in order to build-out their fast-travel network hundreds or thousands of years in advance.
The most important thing to take away from wormhole theory is that somehow, for some reason, these links between disparate parts of the universe of spacetime must form. I am currently unfamiliar with any theory that might explain why these connections might be. People in sci-fi and physics research postulate that black/white holes are the entrances to wormholes but, let's be honest: a singularity is not a wormhole. It is a point in space that trends towards 0/1 but, mathematically, never reaches it. It's the logarithmic/exponential of the physical universe. We don't need to add on additional characteristics to it/them - they just are the way they are!
Without going further into that, let's get back to drives that actually deliver on warping space in the immediate environment around themselves.
Let's disregard their inherent power requirements. That's a given. Whether we're talking about wormholes, warp drives or hyperdrives we're talking about huge amounts of energy or energy manipulation (for the most part - exceptions noted above).
So, consider a simple warp drive. It 'warps' 'spacetime' in order to get around those pesky limits that mathematically-derived principles like general and special relativity force upon us. There is one fundamental problem here and it is the first, second, third and n+1 problem:
As mentioned above: we are made of spacetime. This is a fundamental concept. In the same way that an atmosphere is made of various gases of chemicals, physical items (baryonic matter) is a part of what constitutes spacetime. It is not separate. Neither, it seems, is energy (if E=MC^2 holds true). This brings about a very simple issue. If you warp space then you must warp spacetime. If you warp spacetime then you must warp everything that is encompassed by it. In the same way that boiling a pyrex beaker of liquid must incorporate boiling the liquid inside of the beaker when calculating how much energy to input.
In sci-fi like Star Trek, they accomplish the warping of spacetime outside of a bubble created by the warp nacelles. However, there is a problem with this and that is that spacetime is connected. You cannot warp around a part of spacetime because the spacetime/warp bubble boundary must always be able to interact with the inside and outside of that selfsame bubble. I won't ask you to imagine a bubble here because that wouldn't be overly simplistic enough but let's just say that you imagined a bubble floating in the air (because of a majority of human psychology you most likely just did) - however, the bubble itself is made of air and must be able to move throughout the air it is moving through while maintaining that connection to the air itself.
A person might imagine this and realise that, not only must the bubble created maintain the area inside the bubble but it must also convert the incoming air into the warped space of the bubble volume and the exiting space from the bubble volume back into normal, non-warped air. The spacetime encapsulated within a warp bubble must remain, at all times, in complete communication with that spacetime without a bubble in order for its immediate and complete reintegration with spacetime upon the bubble's destruction.
The further problem with this concept is that, if the spacetime within a bubble must remain in connection with that without, then what is within will be transversed along the vector of the travel of the warp bubble. i.e. any item without the bubble with be subsumed by the bubble, allowing contact at whatever relativistic speeds the item is travelling at with anything inside the bubble. You may be a space ship travelling at 100,000 km/s (w.r.t. Earth) but you will still encounter that asteroid or micrometerorite at its actual speed relative to yourself travelling normally through space whether it takes you 10 seconds or 100 years to reach it.
i.e. A warp bubble is no protection against travelling through space: it does not deviate space around the bubble.
That, right there, completely nullifies any sort of sci-fi principle of a localised warp drive as being useful in travelling through space - unless there are 'magical' shielding systems like there are in Star Trek.
The upside of this is that it is consistent with everything we currently observe due to relativity and gravity. The Earth, the sun, the supermassive-black hole at the centre of our galaxy - they all move through spacetime whilst deforming/warping spacetime. Being a sci-fi fan, you may not find this comforting because there's no faster-than-light (FTL) result at the end of this. You can have relativistic effects but they are not a panacea for long-distance space travel.
There is also an indirect result of this line of thinking - at least according to my logic.
We would be unable to detect gravity waves. (Please see update at the end of the article)
This, unlike the inability to potentially travel through space at speeds faster than light, does have a really big effect on our understanding of our universe. Gravity waves are a predicted phenomenon that we would expect to observe based on certain predicted principles of general relativity. The problem here is that, something like eLISA will never work. We cannot detect something that affects the very nature of ourselves. We cannot directly measure 'gravity' any more than we can measure the effect that 'energy' has on spacetime. We can indirectly measure the effects of gravity by observing the effect on physical objects that incorporate mass and energy but not the 'gravity' force itself.
In fact, we still have yet to be able to detect the theoretical graviton - if it exists. There's no reason why it would be an individual particle or force more than a derived aspect from the existence of spacetime itself. Think about it: if gravity was particulate-based, then each and every atom and section of spacetime must be inundated with innumerable particles from each and every other particle/energy source in order for that information to be propagated. Compare this to the completely inaccurate but appropriate in this instance of the example of space being represented by a sheet of fabric being deformed by a melon. There's no constant communication between the melon and an apple or raisin dropped near the edge of the sheet of fabric - each item knows exactly the relationship it has to the energy/mass density of the other, regarding the shape of the sheet.
Now, in space, distances are so great that our theories of relativity may hold up and all gravitational information is traversed at the speed of light as a maximum. However, even accepting this limitation (in which other case it may not be limited but might be instantaneous/contiguous) how would we be able to observe any difference in our physical universe? We want to watch one object through another one or two objects over a relatively short astronomical distance through which spacetime itself will be altered. We can't even detect the distortion of spacetime for orbiting satellites (we can observe and through this, calculate the effects in order to correct the differences - see GPS and Glonass) but we expect to be able to see the effects on spacetime from objects that are so far away that their effects on our local space will be inclusive?
This is another oversimplification but think of it like this anyway:
You're on a lake. You drop a stone into the lake. You can see the ripples spreading out. Now, you have a friend on the other side of the lake. You ask them later whether they saw your ripples. In spacetime terms, even though there are no winds (there are) and no other sources of ripples (there are) they reply "no" and the reason is not that the ripples aren't there - it's that they are part of the waterscape by the time they get to him.
The difference between the example and what is currently being explored is that we think that we are able to be close to the stone-dropper and that by being closer, we can observe the ripples in the water. The problem with this approach is that we are considering ourselves able to observe a discreet distance and that a 'wave' of gravity exists rather than a wave a spacetime. Thinking about the problem the other way around - you would not expect to notice the difference between the time experienced for the observer around a black hole or in Earth orbit when transposed between those two situations (this is part of general relativity's time dilation) so why would we expect to see the opposite effect on spacetime - that of gravity at a distance? It's just an effect on the curvature of spacetime.
Another thing we would expect to observe if gravity did behave this way is 'delayed drag'. I've never seen anyone mention delayed drag before but it would be a directly attributable effect of gravity waves and 'limited by the speed of light' gravity'. Basically, what we would see is that it would take the normal gravitational effect of interacting bodies of mass and add on a certain amount extra - the effects would be multiplied by distance.
i.e. Very close objects would behave as we currently observe. Very distant objects would behave by 'delaying' their movement due to gravitational interaction because they wouldn't feel it until later. Similarly, for huge interstellar objects such as galaxies, parts of objects would experience gravity at different points in time - resulting in observable ripples or deviations in their formation or continued cohesion.
So far as I'm aware - this does not occur.
Ultimately, it does not appear that:
1) We can harness enough energy to manipulate spacetime in order to warp it to our satisfaction in order to potentially travel faster than light
2) We can separate spacetime from itself and reintegrate it so that we are not just moving a bit of warped spacetime through itself any more than any physical object like a human or planet does.
3) We would be able to detect any sort of deviation to spacetime other than through predicting it theoretically.
UPDATE:
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| Art by Funerium on DA |
There are actually many sci-fi misconceptions about space and many tropes used regarding this part our understanding but I'm only going to focus on one: warping space.
Space as we refer to it is (according to our current limited understanding) actually a continuous mesh of physicality, energy and time - whatever that may actually turn out to be! Most people popularly call this construction Spacetime.
The important thing to note about spacetime is that no constituent of this can be separated completely from the rest of it. Much as particle-wave duality has no separation - i.e. everything is a particle and a waveform, including macro objects like humans, trees, planets etc. - spacetime is its own thing. It is all around us, within us and part of us. In many ways, George Lucas was correct about The Force: including that we can affect it.
Don't get any hasty ideas now because we can't affect it in any 'conscious' manner. We affect it by 'being'. Simply existing in our own configuration, our own mass has an imprint and waveform on the very fabric of spacetime. It's a very small imprint but it exists nonetheless.
So taking these concepts further lets get onto the topic at hand: warping space.
Usually warping space is used as an idea of how to manipulate the universe around us in order to get around that pesky limitation of the speed of light. In the 1930's-1950s science fiction authors came up with a very convenient plot device - hyperspace. Hyperspace is not a warping of space but is actually entering into another, smaller (or longer, depending on your point of view) dimension of reality, allowing an object to travel outside the limitations of the physics of spacetime. However, there was usually an energy barrier needed in order to achieve this 'state'. (The 1961 book, "Time is the simplest thing", is one of the exceptions)
Later on, in the 1940s-1950s Asimov, among others, started mentioning 'space-warp' engines in their fiction and thus the warp drive was born. There may be earlier examples but, accordingly, that era of literature tends to be less well available on the internet and also less critiqued. Obviously, to any semi-literate or TV-conscious sci-fi aficionado, the concept of the warp drive was popularised by Star Trek and entered into the mainstream consciousness freely from the 1960s-onwards.
What is interesting is that this concept of travelling faster than light, in order to get somewhere to move a story along or even within a character's own lifetime, came along well before the sound barrier was a commonly understood problem. The time problem of travel to distant places precluded the notion of limitation of speed within a given fluid. Mach speed and supersonic, both common terms that you may assume came before the concept of a warp drive actually came after (some time around world war II). This is, of course, ignoring the concept of the speed of light being limited by spacetime because it encompasses physical materials, much like how the speed of light is different depending on whether it is travelling through the vacuum of outer space or a crystal prism... or even water. However, general relativity limits the speed of light in a given material and this theory has no concept of being able to overcome those limitations - unlike the movement of a physical object past the speed of sound.
Asymptotically, the concept of travelling through a spatial warp (often referred to as a wormhole) was also developed quite well after Einstein's theories were taken on board in the physics world. In 1921, mathematician Hermann Weyl derived mathematical situations where a physical bridge in spacetime could possibly occur but it was John Archibald Wheeler in 1957 who coined the term 'Wormhole' and went into further theoretical detail.
While wormholes are a form of warp travel, and thus warping spacetime, they are not considered a warp drive unless the drive itself is creating a wormhole. This sort of representation is usually a lesser-used convention of the sci-fi medium and is usually used in contexts of lesser technologically-advanced species whereby they have sent out 'reconnaissance' vessels in order to build-out their fast-travel network hundreds or thousands of years in advance.
The most important thing to take away from wormhole theory is that somehow, for some reason, these links between disparate parts of the universe of spacetime must form. I am currently unfamiliar with any theory that might explain why these connections might be. People in sci-fi and physics research postulate that black/white holes are the entrances to wormholes but, let's be honest: a singularity is not a wormhole. It is a point in space that trends towards 0/1 but, mathematically, never reaches it. It's the logarithmic/exponential of the physical universe. We don't need to add on additional characteristics to it/them - they just are the way they are!
Without going further into that, let's get back to drives that actually deliver on warping space in the immediate environment around themselves.
Let's disregard their inherent power requirements. That's a given. Whether we're talking about wormholes, warp drives or hyperdrives we're talking about huge amounts of energy or energy manipulation (for the most part - exceptions noted above).
So, consider a simple warp drive. It 'warps' 'spacetime' in order to get around those pesky limits that mathematically-derived principles like general and special relativity force upon us. There is one fundamental problem here and it is the first, second, third and n+1 problem:
As mentioned above: we are made of spacetime. This is a fundamental concept. In the same way that an atmosphere is made of various gases of chemicals, physical items (baryonic matter) is a part of what constitutes spacetime. It is not separate. Neither, it seems, is energy (if E=MC^2 holds true). This brings about a very simple issue. If you warp space then you must warp spacetime. If you warp spacetime then you must warp everything that is encompassed by it. In the same way that boiling a pyrex beaker of liquid must incorporate boiling the liquid inside of the beaker when calculating how much energy to input.
In sci-fi like Star Trek, they accomplish the warping of spacetime outside of a bubble created by the warp nacelles. However, there is a problem with this and that is that spacetime is connected. You cannot warp around a part of spacetime because the spacetime/warp bubble boundary must always be able to interact with the inside and outside of that selfsame bubble. I won't ask you to imagine a bubble here because that wouldn't be overly simplistic enough but let's just say that you imagined a bubble floating in the air (because of a majority of human psychology you most likely just did) - however, the bubble itself is made of air and must be able to move throughout the air it is moving through while maintaining that connection to the air itself.
A person might imagine this and realise that, not only must the bubble created maintain the area inside the bubble but it must also convert the incoming air into the warped space of the bubble volume and the exiting space from the bubble volume back into normal, non-warped air. The spacetime encapsulated within a warp bubble must remain, at all times, in complete communication with that spacetime without a bubble in order for its immediate and complete reintegration with spacetime upon the bubble's destruction.
The further problem with this concept is that, if the spacetime within a bubble must remain in connection with that without, then what is within will be transversed along the vector of the travel of the warp bubble. i.e. any item without the bubble with be subsumed by the bubble, allowing contact at whatever relativistic speeds the item is travelling at with anything inside the bubble. You may be a space ship travelling at 100,000 km/s (w.r.t. Earth) but you will still encounter that asteroid or micrometerorite at its actual speed relative to yourself travelling normally through space whether it takes you 10 seconds or 100 years to reach it.
i.e. A warp bubble is no protection against travelling through space: it does not deviate space around the bubble.
That, right there, completely nullifies any sort of sci-fi principle of a localised warp drive as being useful in travelling through space - unless there are 'magical' shielding systems like there are in Star Trek.
The upside of this is that it is consistent with everything we currently observe due to relativity and gravity. The Earth, the sun, the supermassive-black hole at the centre of our galaxy - they all move through spacetime whilst deforming/warping spacetime. Being a sci-fi fan, you may not find this comforting because there's no faster-than-light (FTL) result at the end of this. You can have relativistic effects but they are not a panacea for long-distance space travel.
There is also an indirect result of this line of thinking - at least according to my logic.
We would be unable to detect gravity waves. (Please see update at the end of the article)
This, unlike the inability to potentially travel through space at speeds faster than light, does have a really big effect on our understanding of our universe. Gravity waves are a predicted phenomenon that we would expect to observe based on certain predicted principles of general relativity. The problem here is that, something like eLISA will never work. We cannot detect something that affects the very nature of ourselves. We cannot directly measure 'gravity' any more than we can measure the effect that 'energy' has on spacetime. We can indirectly measure the effects of gravity by observing the effect on physical objects that incorporate mass and energy but not the 'gravity' force itself.
In fact, we still have yet to be able to detect the theoretical graviton - if it exists. There's no reason why it would be an individual particle or force more than a derived aspect from the existence of spacetime itself. Think about it: if gravity was particulate-based, then each and every atom and section of spacetime must be inundated with innumerable particles from each and every other particle/energy source in order for that information to be propagated. Compare this to the completely inaccurate but appropriate in this instance of the example of space being represented by a sheet of fabric being deformed by a melon. There's no constant communication between the melon and an apple or raisin dropped near the edge of the sheet of fabric - each item knows exactly the relationship it has to the energy/mass density of the other, regarding the shape of the sheet.
Now, in space, distances are so great that our theories of relativity may hold up and all gravitational information is traversed at the speed of light as a maximum. However, even accepting this limitation (in which other case it may not be limited but might be instantaneous/contiguous) how would we be able to observe any difference in our physical universe? We want to watch one object through another one or two objects over a relatively short astronomical distance through which spacetime itself will be altered. We can't even detect the distortion of spacetime for orbiting satellites (we can observe and through this, calculate the effects in order to correct the differences - see GPS and Glonass) but we expect to be able to see the effects on spacetime from objects that are so far away that their effects on our local space will be inclusive?
This is another oversimplification but think of it like this anyway:
You're on a lake. You drop a stone into the lake. You can see the ripples spreading out. Now, you have a friend on the other side of the lake. You ask them later whether they saw your ripples. In spacetime terms, even though there are no winds (there are) and no other sources of ripples (there are) they reply "no" and the reason is not that the ripples aren't there - it's that they are part of the waterscape by the time they get to him.
The difference between the example and what is currently being explored is that we think that we are able to be close to the stone-dropper and that by being closer, we can observe the ripples in the water. The problem with this approach is that we are considering ourselves able to observe a discreet distance and that a 'wave' of gravity exists rather than a wave a spacetime. Thinking about the problem the other way around - you would not expect to notice the difference between the time experienced for the observer around a black hole or in Earth orbit when transposed between those two situations (this is part of general relativity's time dilation) so why would we expect to see the opposite effect on spacetime - that of gravity at a distance? It's just an effect on the curvature of spacetime.
Another thing we would expect to observe if gravity did behave this way is 'delayed drag'. I've never seen anyone mention delayed drag before but it would be a directly attributable effect of gravity waves and 'limited by the speed of light' gravity'. Basically, what we would see is that it would take the normal gravitational effect of interacting bodies of mass and add on a certain amount extra - the effects would be multiplied by distance.
i.e. Very close objects would behave as we currently observe. Very distant objects would behave by 'delaying' their movement due to gravitational interaction because they wouldn't feel it until later. Similarly, for huge interstellar objects such as galaxies, parts of objects would experience gravity at different points in time - resulting in observable ripples or deviations in their formation or continued cohesion.
So far as I'm aware - this does not occur.
Ultimately, it does not appear that:
1) We can harness enough energy to manipulate spacetime in order to warp it to our satisfaction in order to potentially travel faster than light
2) We can separate spacetime from itself and reintegrate it so that we are not just moving a bit of warped spacetime through itself any more than any physical object like a human or planet does.
3) We would be able to detect any sort of deviation to spacetime other than through predicting it theoretically.
UPDATE:
So, gravity waves have been detected (or at least what the researchers think are gravity waves). So I'm probably wrong in my understanding! This is cool but the details are still very light and I have a couple of questions regarding the discovery.
First, I would really love to understand why, if space is contracting and expanding - i.e. the lengths of the distance the laser has to travel are altering very slightly, time is not also altering to match that. Supposedly, gravity is the cause of time dilation by deforming spacetime - the larger the gravitational field, the more time is affected.
If the ripples that were detected are gravity waves then why is only space affected by them? Thus the time it takes for light (the speed of which is constant in any frame of reference within identical material) to travel across an area affected by the ripple is inconstant... this seems like it should not occur. We're effectively saying that gravity stretches space, making three dimensional distances longer or shorter but has either no effect or a much weaker effect on time experienced.
Second, I'm having a hard time understanding why gravity does not interact with itself. I mean, we're talking about a massive event, a long time ago over a huge distance:
"the LIGO team estimates that the event that generated the gravitational waves occurred 1.3 billion years ago. That's when two black holes, one 29 times the mass of the Sun, the second 36 times, spiraled into each other."
Those gravity waves have travelled over 1.22993x10^22 (that's 12,299,300,000,000,000,000,000 km). We're saying that, in all that time there have been no other interactions with gravitational fields, waves perpendicular (or at some angle) to the ones we observed? We just happened to observe them perfectly? What about the stretching/creation* of spacetime as the universe expands?
 |
| The data as presented by Ars Technica |
Looking at the graph above there is very little interference at all in those signals. In fact, to my mind they look too perfect. Now, that doesn't mean to say that they are - I have no idea what sort of scale we're looking at here. Often, when you zoom in on data it appears more noisy, so this could be a zoomed-out view of the data... but it's weird how all of a sudden the inherent noise of the system is just gone, even though the signal is not so much larger than the baseline. I mean, the average noise of the baseline is 0±0.5 and the signal is 0±1.0, I'd expect to see more of the variations in the signal between 0.39-0.42 seconds.
Third, I haven't see it explained how the researchers pinpointed what caused the waves in the first place. Maybe they got a team of telescopes to view the general direction of the sky as soon as they received the result and they found, out of all the energetic sources of light in the sky, this event (I assume there would be a lot of X-rays from a merging of black holes). This is just a minor question but I'm looking forward to better reporting on this event.
Overall, this is an exciting event and whatever it turns out to be will be very important in our understanding of the universe!
*I don't think we have any strong proposed theories on this aspect of the universe yet so I'm not sure on how it might affect the contents of the universe.
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