4 ms·
EDIT as a commenter below has kindly pointed out, our current models indicate that the answer to this question is "no", per https://www.youtube.com/watch?v=QMFL
by anonym29 3y ago
EDIT as a commenter below has kindly pointed out, our current models indicate that the answer to this question is "no", per https://www.youtube.com/watch?v=QMFLcmsjOBg https://www.youtube.com/watch?v=QMFLcmsjOBg
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This is all firmly outside my technical discipline, but aren't there some theories that faster-than-light travel might be achieved by bending spacetime around a spacecraft, as opposed to trying to propel the spacecraft through space?
I really want to emphasize that this is entirely speculation, but is it possible that these gravitational waves could be the "ripples" produced in the wake of such faster-than-light travel, the same way a boat travelling through a body of water leaves ripples in the water behind it?
- sidcool 3y agoTheoretically it's impossible to travel through space at or more than speed of light. But space itself can move faster than light speed, and a warp drive would help something similar that you mentioned. That is possible theoretically. But the amount of energy or mass it needs is very high and no current technology (or in foreseeable future) can achieve it. So FTL remains a dream. My hunch based on nothing is that we will achieve FTL no earlier than 2250.
- SketchySeaBeast 3y ago> My hunch based on nothing is that we will achieve FTL no earlier than 2250. I see you too have been forced to give PMs estimates when you don't understand the problem.
- actionfromafar 3y agoAnd without a later bound, so a very reasonable estimation too.
- time0ut 3y agoIs this before or after the estimate is rejected and arbitrarily cut in half?
- davrosthedalek 3y agoYeah, we really should have had FTL by 1125! You'll have to work overtime for the next sprint.
- sidcool 3y agoLol I feel you.
- automatic6131 3y agoIt's fun to imagine the species in x-hundred years. My college physics professor once told us that in 500 years, physics professors will still teach Maxwell's equations in the format he was showing us. And honestly, I think he's right. Somethings we will do the same way for hundreds of years, like the wheelbarrow will still exist in 500 years as it has for likely the previous 5,000. Otoh, I doubt we will be going faster than light this millenium.
- rkagerer 3y agoNaw in another 500 they'll be antigravbarrows
- nine_k 3y agoWe still teach the Newton laws that are comparably old. We also teach that they are approximate, but work flawlessly for household-scale speeds and masses.
- zzzeek 3y agothere will be "physics professors" in 500 years, I see we are being optimistic about humanity
- adgjlsfhk1 3y agothe only plausible possibility for a major change in Maxwell's laws is if we discover a magnetic monopole. It's fairly unlikely, but there isn't a solid reason one shouldn't exist as far as I know.
- SkyMarshal 3y agoYeah the only energy source that can produce enough energy to power an Alcubierre drive (warp drive) that humanity has ever even conceived is a matter-antimatter reactor. But we don’t even fully understand matter, much less antimatter, and are pretty far from that. 2250 at the earliest is not an unreasonable estimate.
- ben_w 3y agoAntimatter wouldn't be even close to powerful enough, and both matter and antimatter have got the wrong sign for every (or almost every, depending on which headline I trust) warp drive variation. As antimatter is as powerful as one can get, it not being powerful enough is a good reason to think it's not going to work.
- amelius 3y agoHow would someone _inside_ space make use of FTL movement of space itself?
- DexesTTP 3y agoTo simplify, the same way that a surfer on the sea can use the movement of the sea itself (waves) to surf! An Alcubierre drive (they're theoretical) would basically constantly compress the time curve of spacetime in front of the craft, allowing the craft to "ride" this compression as it moves forward, which means that the local speed of light of the craft is faster than the speed of light of an external observer. Note that the main issue we have is to find something that can compress space, and then to have it have enough energy for it not to be trivial (because 110% of the speed of light, while technically FTL speed, is still very slow for interstellar travel). And of course, while the existence of something that does this spacetime curve compression fits the math we have, we've yet to find a material or technique that actually does so.
- amelius 3y agoSorry, I don't get it. Imagine you are on a rubber ruler. You can move at most 1 mark per second on the ruler. This is true regardless of how much the ruler is stretched or compressed. So to move from mark 1 to mark 100 will always take the same time at top speed, regardless of any stretching/compression.
- cglan 3y agoDon’t take my word at all, but I think in your analogy you can’t imagine it as you’re only allowed to go 1 ruler tick a second, but imagine you can only move 1mm per second. If you compress the rubber ruler you traverse more ruler per second than before while still going the Same speed
- dotnet00 3y agoThe idea is similar to how we detect gravitational waves in interferometers, when space gets compressed, the distance the photon has to travel shrinks slightly. To take your ruler example, if you compress it by 1mm, you can traverse its entire length traveling 1mm less than before, thus, from the reference frame of someone who can't see that you've compressed the ruler, you've traveled slightly faster.
- mjburgess 3y ago'space' isnt a substance that can move at any speed. What's meant by the claim that 'space moves faster than light' is that extremely distant objects are moving away from each other, relative to each other, 'faster than light' -- which is permitted, so long as that distance can never be bridged by light. The claim amounts to, in other words, that the universe is so large that we can compare objects at distances greater than those light could travel between them, and if we do that, they travel faster than light. This is an "illusion in measurement" more than anything else. Nothing is travelling faster than light.
- TechBro8615 3y agoHere's an article that explains this distinction in detail: https://medium.com/the-infinite-universe/why-galaxies-receding-faster-than-the-speed-of-light-are-still-visible-664ff21f0829 https://medium.com/the-infinite-universe/why-galaxies-recedi...
- rkagerer 3y agoSo it can't fold on itself and form a wormhole that bridges light?
- gpderetta 3y ago> space moves faster than light I think this simply refers to the metric expansion of the universe [1]. While nothing actually travels FTL, the distance between some objects really expands faster than FTL and is not an illusion. [1] https://en.m.wikipedia.org/wiki/Expansion_of_the_universe https://en.m.wikipedia.org/wiki/Expansion_of_the_universe
- mjburgess 3y agoThe illusion is the impression that something moves faster than light. 'distances' arent literally 'expanding' -- this metaphor of expansion describes a shift in the matter distribution of the universe over time which seems like an expansion of an underlying substance 'space'. This is the illusion. The metric is just that matter distribution. And the fact of its changing we call 'expansion'. This metaphorical, substantival language, creates a lay impression that some physical object moves faster than light.
- SketchySeaBeast 3y ago> Whereas the original discovery spotted waves originating from the collision and merger of two star-sized black holes, the most likely source of the latest finding is the combined signal from many pairs of much larger black holes — millions or even billions of times the mass of the Sun — slowly orbiting each other in the hearts of distant galaxies. These waves are thousands of times stronger and longer than those found in 2015, with wavelengths of up to tens of light years. By contrast, the ripples detected since 2015 using a technique called interferometry are just tens or hundreds of kilometres long. Seems like they probably know where these are coming from. I imagine, like your boat analogy, that we can observe massive natural oceans swells and wouldn't notice the wake of a boat as it moves across the ocean.
- dylan604 3y ago>with wavelengths of up to tens of light years. from a layman's perspective, this sounds crazy cool that they were able to "see" this in the data. seems like one of those things that would be easy to miss from being scoped in and only discoverable after zooming back out. waaaaay out.
- RhodesianHunter 3y agoWe're using what we can measure/see of distant stars for these measurements, so it is indeed zoomed way out.
- psychphysic 3y agoThe energies involved are stupendous. It would be like being hit by a tsunami and wondering if a cruise ship caused it. But on a galactic scale.
- edgyquant 3y agoAre not the energies required for a theoretical warp drive also stupendous?
- psychphysic 3y agoQuite likely. I'd say it's at present beyond our comprehension. A big enough cruise ship, accelerating fast enough, could cause a tsunami but it'd be far beyond anything we could reason about sensibly. If they control that much energy, maybe it's waves from their equivalent of a microwave oven.
- QuadmasterXLII 3y agoWe’re working with numbers with 30s and 40s in the exponent- plenty of room for stupendous things to be stupendously different
- akiselev 3y agoThe original Alcubierre paper came up with the energy equivalent of the entire mass of Jupiter, if I remember correctly.
- Retric 3y agoWhich as shocking as it sounds still small compared to large gravitational waves. The merger of black holes radiate something like 10% of that mass as gravitational waves. Start talking 2.5+ million solar masses black holes and ~500,000 solar mass worth of energy in gravitational waves seems plausible though obviously rare.
- tnowacki 3y agoPBS Spacetime did an episode on this just recently! https://www.youtube.com/watch?v=QMFLcmsjOBg https://www.youtube.com/watch?v=QMFLcmsjOBg In the video, they mention that the models we have for FTL (by bending spacetime) wouldn't generate ripples in this way. We could however detect ripples from a really massive ship accelerating really really quickly.
- colechristensen 3y agoAre there theories? Yes! Do they require a long list of impossible things to work? Also yes! There are entirely valid solutions in general relativity which allow for an object in a pocket of spacetime with other spacetime warped around it in such a way that, more or less, space is moving but not the object. However achieving the arrangement of spacetime to make this happens requires many things which are impossible, aren't known to exist, or require something like all the energy in the Universe to achieve. Also there are no valid known solutions that transition from normal space to this special spacetime arrangement, so it could only exist if it always existed. So it comes down to: we're pretty sure such things are not actually possible but we know where to look and what problems to solve if it were. Occasionally we see a paper which removes some of the impossible things from the list. It's one of those "unlikely but maybe someday" kinds of things.
- zackmorris 3y agoThis video might help understand where mass comes from and how to potentially modulate it, because mass can be thought of as bound energy creating voids in the gluon field: https://m.youtube.com/watch?v=Ztc6QPNUqls https://m.youtube.com/watch?v=Ztc6QPNUqls The Higgs mechanism affects electrons, not quarks, and is only responsible for about 1% of matter's mass. Most mass comes from the binding energy between quarks, which creates flux tubes between quark-antiquark pairs. If we add more energy to pull quarks apart, eventually the total energy added exceeds the mass-energy equivalence of another quark-antiquark pair, so a new pair gets created from the vacuum. I believe this is related to the Casimir effect, but IANAP (physicist). Keep in mind that the mass-energy equivalence also applies to time. So like in the movie Interstellar, when they go down to the water planet, gravity is so high that time passes slower for them than the guy in the orbiting ship. In other words, the ship sees the landing craft move slower and slower as it approaches the surface. This difference in the speed of time near a gravity well is what slows the inner edge of a satellite slightly more than the outer, curving it along the path of the orbit, which from the satellite's perspective feels like a straight line at that velocity, because it's weightless and feels no other acceleration other than tidal force. So if someone could move large amounts of energy into a confined space with some kind of flux capacitor (is this a pun? I don't even know anymore), they could slow time there and create a virtual mass through mass-energy equivalence by E=mc^2. If they did it in front of the satellite, it would begin to increase in velocity towards that mass. So this is sort of a warp drive mechanism, although I don't know how you'd confine it, and the energies involved would be planet-scale to achieve 1 g of acceleration like near the Earth. Also if someone made a closed loop where electron-positron pairs were sent one way, then their energy was used to create quark-antiquark pairs sent the other way, there might be a 1% imbalance in mass due to the Higgs mechanism, which would add momentum to the loop opposite the direction of the heavier stream. Although due to conservation of momentum, I suspect that this wouldn't actually happen, because any momentum above light pressure should get lost to heat/entropy/etc. But it would be a fun experiment to try. The same experiment would also work just sending light energy photons one way and matter-antimatter pairs back the other way, but I've never seen a proof as to why this would or wouldn't beat light pressure. This would be a reactionless rocket, not a warp drive. If there's a gravity field like a gluon field, just with slightly different rules, then I don't see why it couldn't be modulated. In fact, I think that the dark matter strands connecting galaxies are densities where perhaps something like slowed neutrinos or axions collect and slow time. They could even be places where gravity "flows" along eddies left over from the Big Bang, although this seems strange to us because gravity normally only flows into gravity wells. There's also currently no explanation for the Hubble constant in the expansion of the universe, so perhaps something is creating space over time. So I don't see why space couldn't be created behind a craft to push it forward. We just don't know how. There are so many unexplored interactions like this, that I don't think any physicist can confidently say that warp drives, reactionless rockets and folding space are impossible. Which means that I give it 50/50 odds that some kind of sci-fi space engine will be invented within the next few decades, probably starting with a reactionless drive like the EmDrive, which (if it works) uses resonance to time the interaction of microwaves with the rebound of atoms in an asymmetric field, similar to the Biefeld-Brown effect explored by Thomas Townsend Brown in the 1920s, which was later found to just be an electrohydrodynamic (EHD) effect: https://en.wikipedia.org/wiki/Reactionless_drive https://en.wikipedia.org/wiki/Reactionless_drive https://en.wikipedia.org/wiki/EmDrive https://en.wikipedia.org/wiki/EmDrive https://en.wikipedia.org/wiki/Biefeld–Brown_effect https://en.wikipedia.org/wiki/Biefeld–Brown_effect Unfortunately only physicists are privy to the mental associations which allow thought experiments like this. Textbooks leave us mainly theory and equations, not insights or abstractions. Physics formulas are like trying to understand the behavior of an app from its assembly language. So in a very real way, academic gatekeeping prevented almost everyone from contributing. For every divergent thinker like Einstein, there are 100 convergent thinkers who judge skeptically and crush ideas into oblivion. I'm just an armchair warrior full of derivative ideas who has never invented anything, who would love to run experiments like these. But just like you the reader, I'll spend the rest of my life making CRUD apps to make rent because billionaires have all the money, instead of getting to be like Dr. Gillian Taylor in Star Trek IV, suddenly able to explore every possibility under the freedom of UBI. That was a joke, but not really.
- wes-k 3y agoFuturama had an episode about that! "I understand how the engines work now. It came to me in a dream. The engines don't move the ship at all. The ship stays where it is and the engines move the universe around it." ―Cubert Farnsworth https://futurama.fandom.com/wiki/Dark_Matter_Engine https://futurama.fandom.com/wiki/Dark_Matter_Engine https://www.youtube.com/watch?v=1RtMMupdOC4 https://www.youtube.com/watch?v=1RtMMupdOC4