As lim (pg. -> 100) 1/(100 - pg.) we are compelled to make a new [Science] thread.
All sciences and related fields are welcome for discussion.
To start things off,
WARP DRIVE!
Well, not FTL, but a good theoretical foundation for warp drive (paper isn't available or on arXiv yet):
https://www.youtube.com/watch?v=8VWLjhJBCp0
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I'm not going to get my hopes up until this goes through peer review and someone can explain it better.
Doing it conventionally is, uh, also ridiculously energy-intensive.
If you can go from zero to "almost, but not quite, c" at the flick of a switch it may be worthwhile since you'd be vastly decreasing your travel time.
In theory
I don’t think so. IIRC the time dilation cause by the compression and expansion of space ends up cancelling out to what the dilation would be if it had travelled the same distance in the same time conventionally when viewed by the rest of the universe. Same reason FTL warp drive still lets you time travel.
Edit: apparently I’m misremembering on that, it looks from reading a bit that an FTL alciaberre drive would act like a “slow wormhole” and you could basically come out of the journey at whatever time you wanted relative to the rest of the universe? No clue how that would work slower than light.
Also it seems like the people/objects inside the bubble wouldn't have any g forces acting on them.
So it'd be hella more manoeuvrable
I think this would be quite a big deal if we could get it working.
There’s no real such thing as a universal time or t=0 across space.
If you can make trips between places without time dilation (whether via wormhole or alcubierre drive or whatever) this essentially locks those places in a frame of reference with each other which doesn’t make sense when viewed against the rest of the universe.
Like you travel to alpha centauri at .5c. You make a journey that from the point of view of Bob on earth looks like it takes about 17 years, but for you it only takes 15 years. Now your buddy Cal takes his alcubierre drive to Alpha Centauri that doesn’t experience time dilation but moves at an apparent speed of .5c from earths point of view. From Bobs point of view it takes 17 years, from Cals point of view it takes 17 years. However from your point of view it still takes 17 years for Cal to make his journey but only 15 for you (remember he hasn’t actually moved so his apparent time to you should look no different than someone still on earth). So Cal experiences no time dilation from Bobs point of view but experiences 2 years from your point of view. But why is Bob’s frame of reference privileged over yours in this case? From the point of view of earth you would both appear to be at the same point on every part of the journey and arrive at the same time, but from your view Cal would be behind you the whole way and would arrive at alpha centauri 2 years after you got there.
I think the lack of g forces would basically enforce this drive becoming widely used if we move out into space in any real capacity, and especially if there's any kind of conflict. If it's possible to create it, of course.
Your reaction time doesn't really change. Time still runs at 1/s per 1/s.
Isn't that what it means to get rid of time dilation? At light speed, your reaction time is literally zero with time dilation. If it feels like 10 years instead, how would that not allow you to do things during those 10 years?
You can't actually ever hit c, for one. But no your personal time is always one second per second. It's everyone else that sees you running slow relative to them. Even if you somehow eliminated that effect- which is going to mean re-writing how we understand the universe- there's still the slight problem of the light delay. Anything you're seeing with will be moving almost your speed. It'd be like navigating a near-supersonic jet by sonar.
If space time itself is moving, the current rules don't necessarily apply anymore.
So parking would be a somewhat delicate process.
Thanks for the link. I ran across this other video in her channel that is both interesting and, at the very end, incredibly savage:
https://youtu.be/9qqEU1Q-gYE
Its not really a thing to work out, its honestly probably impossible just because of the way it fucks with the timeline, even if it doesn’t directly violate causality.
Like in the example above, from the perspective of the two travellers, one has time to go get an associates degree on alpha centauri while the other doesn’t see any time at all between their arrival, the alcubierre guy literally sees them pull up at the same time while the normal travel guy sees himself as having 2 years of time to fuck around before the other guy gets there. An observer on alpha centauri would see a delay, but not one that exactly matches the first traveller IIRC. So you would have three people experiencing three different timelines and sequences of events, all of which could have different consequences on the future.
Sabine Hossenfelder is the hero we need
Is the earth a dragon?
No, this is a common misconception because people can see scaled legs over the edge, but the earth is actually a flat disc atop four elephants standing on a giant turtle swimming through space.
this isn't how relativity works
no one standing on earth is going to see you traveling away from them at 0.5c and agree with you exactly on how long your trip took
Thats the point, if you strip time dilation out with some theoretical “warp drive” you get frame dragging, so someone travelling in an alcubierre drive would appear to be moving away at .5c to an ouside observer while still having their clocks agree with the person observing it. Which when viewed in the context of special relativity leads to all kinds of time travel, multiple timelines, etc.
“Relativity does not work that way so its probably not possible” is literally the point.
i think there's a misunderstanding of the time dilation issue
the "no time dilation" only occurs inside the bubble, like locking yourself in a room
it's still relativity to any observers, it's not like you can log in to harvard.edu and work on your associates degree while you're in the bubble. you're not actually breaking causality or anything like that. the whole idea of a tunnel in a wormhole is it exists outside of spacetime, allowing faster than light travel without requiring faster than light motion
this bubble drive idea is basically that on a smaller scale that doesn't require negative energy
Relativity saying this cannot happen has no relevance to a warp bubble. It tells relativity to go get fucked.
Or at least, that's my interpretation of how they work. Which you seem to agree with. You just seem to be saying "but this causes paradoxes, so that can't be possible"
If it causes weird time travel shit, it causes weird time travel shit. If its possible, future people will just have to get very good at dealing with weird time travel shit.
And if it is possible, they will.
you can take some textbooks with you in your bubble and complete an associates degree during your travel that you wouldn't have had time to do outside the bubble but that time still occurred to you
So you are saying that from the point of view of an observer outside the bubble there will still be relativistic time dilation? How can that be? Relativistic time dilation is what happens to objects that are moving through space time. This is not really moving through space time. It's space time itself moving. Where's the time dilation coming from?
Which is exactly why it fucks up the timeline, because the rest of the universe is still running on relativity.
You can have a newtonian universe where time moves the same for everyone (well, we can’t, but such a universe could exist and be consistent.)
You can have a relativistic universe where time varies by the frame of reference to the observer, and everything is logically consistent thorough being constrained by the speed of light.
Having little bubbles of newtonian space-time within a relativistic universe fucks things up though. It really fucks things up if you can go faster than light because then you can do things like accidently or deliberately time travelIng by changing direction and violate causality by making closed time loops and the like. It fucks things up less with sublight speeds, but you still end up with things like different observers that end up in the same place but see events in a different order, or have large stretches of time that pop up or dissapear for the observer in the “bubble” vs the rest of the universe (not that they subjectively observe time differently, but that they literally arrive at a different time than they should from the view of the rest of the universe).
Going slower than light actually fucks it up even more because at slower than light speeds the guy within the bubble can theoretically observe the rest of the universe and communicate with it while he or she is traveling.
Yes.
And?
Last I checked physicists would be pretty okay with time being fucked up because they don't even really believe time is a straight line from start to end anyway.
I'm saying if its fucked up, we'd figured out what to do with it. It'd be very interesting times, and nothing like we previously have known. But we'd adapt.
"Time gets fucked up" is not a sufficient reason to say "and so this can't happen".
https://www.youtube.com/watch?v=pTn6Ewhb27k
https://www.youtube.com/watch?v=XRr1kaXKBsU
edit:
And this one, which is about how space expanding doesn't mean local spacetime we experience is expanding.
https://www.youtube.com/watch?v=9DrBQg_n2Uo
Thats not what happens.
What happens is that to the guy in the bubble he literally arrives at the same time as the guy who travelled conventionally. He pulls up on the landing pad at the same time, shakes his hand, both arrive simultaneously.
For the guy who went in the regular spaceship he gets to alpha centauri, takes a community college class, gets married, has a kid, takes a taxi 2 years later and meets warp bubble guy at the launch pad, and shakes his hand.
At no point is there a mechanism to reconcile these alternate chains of events, both guys proceed to live the rest of their lives as if their version of things happened but somehow still occupy the same universe and can exchange information with each other the whole time.
https://youtu.be/2GMW7GZAUfQ
I don't think this is how it works. If Bob were standing on Alpha Centauri he would still perceive the trip as having took you 17 years, not 15 (after he accounts for the time it took light from Earth showing you taking off to reach him). You're the only one who experiences it as 15 years.
(Okay this is maybe fudged a little bit because it assumes Alpha Centauri and Earth are stationary relative to each other, which they are not, but they are certainly far closer to stationary relative to each other than they are relative to you and Cal.)
Thats what normally happens in relativistic travel. Time travels slower for the traveller than either destination (note normally clocks aren’t going to be the same at all on alpha centauri or earth, they are also moving relative to each other). But because the speed of light is an inherent limiter of the speed of travel in relativity, paradoxes get rectified.
Its totally possible from a pair of arbitrary points of view in special relativity for two observers to observe a set of events in different locations in a different order (ie from the milky way you may see a distant supernova in galaxy A occur before B, but from andromeda you may see galaxy b have a supernova before galaxy a). But because of the speed of light limiting flow of information and therefore causality itself every observer internal to the system has a consistent point of view in which causality is maintained.
Because the alcubierre drive is letting you keep the frame of reference of Earth while physically being adjacent to alpha centauri, you are suddenly allowing paradoxes in perspective to have a meaningful impact on events, in a way that just traveling there conventionally doesn’t (because the speed of light and subjective time dilation prevents such paradoxes from occurring and actually mattering, everything “cancels out” so that a coherent time line is visible to any observer which agrees reasonably with any other observer as to “what is actually going on right now at this moment” provided they are in the same location).
This is literally what special relativity does, and anything that bypasses it is going to need to have another mechanism to reconcile synchronicity at local distances and resolve paradoxes, or have observers at the same location disagreeing about what they are observing in the “present”.