/sci/ - Science & Math

[Anonymous No.9627644]

EM drive has been so far a complete meme since then.
but there is also the alcubierre drive. is it a meme or is there some actual practicality with such device?

[Anonymous No.9627647]

>>9627644
you literally would need more exotic matter than the entire observable universe has to power this thing
also, how the fuck would anything survive in the Bubble

[Anonymous No.9627658]

>>9627647
i recall the energy required to run the machine is equivalent of the mass of saturn no?

[Anonymous No.9627662]

>>9627658
>If certain quantum inequalities conjectured by Ford and Roman hold, the energy requirements for some warp drives may be unfeasibly large as well as negative. For example, the energy equivalent of −10^64 kg might be required to transport a small spaceship across the Milky Way—an amount orders of magnitude greater than the estimated mass of the observable universe.

[Anonymous No.9627666]

>>9627662
you can bring that requirement down closer to 0, problem is that it's negative energy and we can't make that

[Anonymous No.9627676]

>>9627662
>In 2012, physicist Harold White and collaborators announced that modifying the geometry of exotic matter could reduce the mass–energy requirements for a macroscopic space ship from the equivalent of the planet Jupiter to that of the Voyager 1 spacecraft (~700 kg)[7] or less,[22] and stated their intent to perform small-scale experiments in constructing warp fields.[7] White proposed changing the shape of the warp bubble from a sphere to a torus.[23] Furthermore, if the intensity of the space warp can be oscillated over time, the energy required is reduced even more.[7] According to White, a modified Michelson–Morley interferometer could test the idea: one of the legs of the interferometer would appear to have a slightly different length when the test devices were energised.[22]

i know this doesn't really refute your point but it seems that the energy required is getting more smaller

[Anonymous No.9627699]

>>9627658
It's even less than that now. Current theory makes it possible to construct a warp drive if you have the mass of the moon.

[Anonymous No.9627764]

>>9627699
No, not mass, you need negative mass/energy and we don't know how to make that.

[Anonymous No.9627787]

>>9627764
Wrong. You just need mass.

[Anonymous No.9627799]

>>9627787
no, for stretching spacetime you need negative mass, to contract it you can use regular mass

[Anonymous No.9627802]

>>9627799
You may be right there. I need to read up some more on this.

[Regression to the mean? No.9627818]

>>9627799
How can you contract part of a fabric without stretching another part at the same time ?

[Anonymous No.9627823]

>>9627818

[Anonymous No.9627824]

>>9627818
The very principle of the warp drive. The very thing that makes it theoretically capable of FTL in our universe, is the fact that patches of space have no limit on the relative velocities they can achieve. If you contract space in front of you, you just fall into it like any other gravity well and stay there. It's only when you balance the contraction in front of you with expansion behind you that the patch of space you are in literally moves forward. Your velocity through spacetime is technically 0, you are just riding a wave that is carrying you with it.

[Anonymous No.9627839]

>>9627644
Alcubierre found a valid solution to the Einstein equation, which means that it should work -- IF you could distort space-time in the manner indicated.
That may not be possible. It takes a massive amount of energy and some of it has to be "negative".
Even if we had the energy, objects inside the "warp bubble" are "causally disconnected" from the outside. That means you can't see, steer, or turn the drive off. So don't envision Star Trek.

Even granting the possibility of creating such a warp, we're no closer to doing so than Neanderthals were to landing on the Moon.
Incidentally, Alcubierre himself doesn't believe it's possible and has commented that, like all FTL schemes, it doubles as a backwards-in-time machine.

[Anonymous No.9627861]

>>9627839
>objects inside the "warp bubble" are "causally disconnected" from the outside. That means you can't see, steer, or turn the drive off.

I think that's bullshit. You can't see behind you, because light can't catch you. Seeing forwards is another matter. If the drive takes energy to use, then it can be turned off. There's a problem about how turning it off releases a big cone of photons trapped in the front of the bubble, which would obliterate your destination.

Lastly, the whole time travel thing is just silly. The only thing it does is violate casuality (which is just the perceived order of events) because people at the destination would see you arrive before they see you leave your starting point. It's like that because you are moving faster than the light that tells them this shit. It's no biggie, nor is it time travel in the sense most people think of it as.

[Anonymous No.9627873]

>>9627861
all faster than light travel implies time travel, there's always a path you can take which brings you back to the place you left before you ever left

[Anonymous No.9627889]

>>9627873
Only in the frame of reference of people around you. They closer they are, the faster you have to move. If they are right next your starting point when you start, you will need to have a journey that's shorter than the time it takes for light to traverse the meter between you and your friend. In which case you will appear to have never moved at all unless your friend has the universe's best slowmo camera. You can never do this to return to a previous point for your own world line. Only for obververs of your world line do things look weird.

[Anonymous No.9627953]

>>9627644
Unless most things we know about physics are false, there is no such thing as negative energy, so for now this isn't possible.

[Anonymous No.9627964]

>>9627644
Lrn2meme fgt pls

[Anonymous No.9627968]

>>9627839
>don't envision Star Trek
BLASPHEMY

[Anonymous No.9627974]

>>9627889
>>9627861
Sounds like you understand SOME physics -- but not enough.
It's not an illusion caused by the time it takes to observe distant events.
Here's Alcubierre's own explanation.
>http://ccrg.rit.edu/files/FasterThanLight.pdf
You can interfere with your own past world-line.

[Anonymous No.9627979]

>>9627968
Burn me at the stake then.
I wouldn't get into one of their transporters either, Heisenberg Compensators or no Heisenberg Compensators.

[Anonymous No.9627988]

>taking the spacetime meme this seriously

[Anonymous No.9628000]

>>9627988
Yeah this, there is no such thing as a 'fabric of space' it's just the only slightly relateable analogy that can illustrate gravity somewhat, it's not what is actually going on.

You'd theoretically need exajoules of power focused in a very small area, even if that kind of power can be generated through fusion reactors a few hundred years in the future there are no materials that can handle anything like that without evaporating instantly and it is likely that we will run into hard limitations that can not be circumvented or negotiated that will prevent humanity from ever proceeding off this planet as human beings.

[Anonymous No.9628041]

>>9627974
I read that and still didn't see anything that disagrees with what I said. It made no attempt to explain how you could go back in time to arrive at a starting point before you physically make a trip by moving faster than light. It just listed a bunch of paradoxes that show why time travel to the past is ridiculous, and some stuff about how people will disagree with event orders when they shouldn't.

It is something of an arbitrary thing to consider with regards to FTL, since doing the stuff that really messes with causality involves returning to your starting point, which at FTL speeds is going to require turns with unsurvivable g forces. For straight trips from A to B, there's no serious game breaking violation. It's all just tricks of light lag.

[Anonymous No.9628068]

>>9627823
>>9627823
>reality is an analogy for the equations
dumb post

[Anonymous No.9628103]

>>9628041
FTL has nothing to do with gee-forces. Everyone agrees you can't simply leave the rockets on and surpass lightspeed.
I've explained this before, so apologies to people who've read it already.

This is called a Minkowski Diagram.
We can’t draw in 4 dimensions, so all 3 dimensions of ordinary space are reduced to the X-axis of the diagram. Motion to the left or right corresponds to movement in space. You’re sitting somewhere right now. You’re not moving. So there’s no motion left or right. But you ARE moving into the future at the rate of 1 second per second. The T axis represents motion in time. With every passing second, you move towards the top of the diagram. Any point in space or time can be shown on this diagram. Motion through space and time is, therefore, a line showing how you got there. This is called your “world line”.

Light travels 300,000 km/sec. A light ray is shown in red and marked C. The diagram has been scaled such that 300,000 km is 10 cm along the X axis and 1 second is 10 cm along the T axis. So the C line is halfway between X and T at 45 degrees. With me so far?

A ship leaves Earth and heads out into space. It travels along the cyan line T’. It is moving slower than light, so at all times a light ray which left Earth when it did is further from Earth than the ship is. Slower than light motion is called Time-like.

The pilot of the ship regards himself as “not moving” once the engines are turned off. He’s just sitting there and it’s the Earth that’s rushing away. That’s a perfectly valid viewpoint and it’s why his path is labeled T’. He’s going straight up HIS time axis.

But ALL observers measure the speed of light to be the same. Light always moves halfway between the T and X axes. If the pilot has a different T axis than you do, he must also have a different X axis. Only way he can measure light to have the same velocity as always. His space-axis is X’

[Anonymous No.9628109]

>>9628103
Now, we’ll imagine an ansible has been invented. An ansible is faster-than-light radio. In fact, it’s instantaneous regardless of the distance between transmitter and receiver. Instantaneous is not really necessary. Any faster than light signaling will do, but it makes the diagrams easier to draw.

At 1, you broadcast an important message over the ansible. What does “instantaneous” mean? It means it takes no time to travel any distance in space. So the dashed gray line is horizontal. No motion in time at all. It is received by the space ship at 2.

The pilot sends a reply. How does it travel? Back to 1? No! That’s silly. Why should it retrace the path along your X axis. There’s nothing special about Earth’s motion. To be consistent, it has to go parallel to the ship’s X axis, the one we called X’. So it reaches Earth at 3. This is BEFORE you sent the original message at 1.

If the message sent at 1 was “planes hijacked to crash in New York”, then the police can take action at 3 to foil the plot. So the planes were never hijacked and you never sent the message at 1. We have a paradox!

[Anonymous No.9628125]

>>9628109
List time around, someone complained that the causality violation was only in someone else's frame of reference.

But you can change to any inertial frame you like at any time.
The ship left Earth at 0 and transmitted the message back at 2.
Then it used its motors to head back to Earth and landed there at 4.
Now it's back in the Earth-frame where it started and where the original message came from -- and where it was received at 3.
The ship can't get back in time to do anything about 911, but the superlight message could.

What you can do with an FTL radio you can certainly do with an FTL ship.

NOW do you understand?
If not, please explain to us where Einstein went wrong. No one else has succeeded yet.
Even invoking "hyperspace" or "warp drive" doesn't permit you to avoid the paradoxes.

[Anonymous No.9628128]

>>9628109
Last time around, someone complained that the causality violation was only in someone else's frame of reference.

But you can change to any inertial frame you like at any time.
The ship left Earth at 0 and transmitted the message back at 2.
Then it used its motors to head back to Earth and landed there at 4.
Now it's back in the Earth-frame where it started and where the original message came from -- and where it was received at 3.
The ship can't get back in time to do anything about 911, but the superlight message could.

What you can do with an FTL radio you can certainly do with an FTL ship.

NOW do you understand?
If not, please explain to us where Einstein went wrong. No one else has succeeded yet.
Even invoking "hyperspace" or "warp drive" doesn't permit you to avoid the paradoxes.

[Anonymous No.9628134]

>>9628103
>>9628109
Given that we had an engine that could thrust long enough to reach 299 792 458m/s without encountering resistance, what would happen to the ship if it reached this speed or a what would happen when it meets some sort of threshold where it can not go beyond?
Why would something happen to it at all? There are no forced exerted on it except for the thrust.

What would happen to the ship from its own point of reference? Any outside point of reference is irrelevant to me, I purely want to know the effects of the speed on the material.

[Anonymous No.9628151]

>>9628134
It gains mass as it reaches a velocity asymptote.

[Anonymous No.9628165]

>>9628151
Thank you.
And if it would go over this asymptote (theoretically) it could only behave like a bunch of photons so all mass would be converted into such particles/waves/energy?

May I ask what principal or formula describes this gaining of mass as its velocity increases?
What is acting on it that would increase its mass as a result of movement? Would its own gravity be affected?

[Anonymous No.9628172]

>>9628134
As the ship approaches lightspeed, nothing obvious happens. If the windows are closed and you can't see outside, there is NO way to tell you are moving. If there was, we could build a "speedometer" to measure Absolute velocity. Since all inertial reference frames are equally valid, there's no such thing.

Light rays continue to zip past the ship at 300,000 km/sec in all directions. If you've been feeling a steady one gee from the acceleration (presumably throttling back the rockets as the ship burns fuel and expels it) you'll continue to feel one gee.

An observer on Earth (or someone near your trajectory but still motionless relative to Earth) will see your acceleration steadily decrease and your clocks run slower and slower.

Again, the pilots see nothing whatsoever happening to their own ship.
Outsiders see the crew almost "frozen" with time-dilation and able to travel immense distances within a short time by the ship's clocks.
Shipboard people see nothing amiss with their clocks, but the external universe appears to contract. The distance between stars is reduced and they can make long flights even though they're moving at less than lightspeed. (Remember, I said that star light still passes them.)

[Anonymous No.9628183]

>>9628165
It can never reach cee, so "what happens when it gets there" is a moot question.
The basic equation is Tau = sqrt(1 - V^2) where V is a fraction of lightspeed. As V approaches 1, tau approaches zero. V > 1 would mean Tau is "imaginary".
Tau is the time-dilation.
Gamma, the reciprocal of Tau, is the mass of the ship. When time is going at 1/10th "normal", the mass of the ship is 10 times "normal" and 10 times harder to accelerate further.
"Normal" means "as seen from Earth". It should be emphasized that none of these effects are an illusion of any sort. They're quite real.

[Anonymous No.9628197]

>>9628183
But according to E=mc2 mass can be converted into energy and only something with the properties of a photon(no mass) can actually go at the speed of light so if we were to accelerate a bunch of matter to as close to the speed of light as possible as seen in particle accelerators, shouldn't it disintegrate and transition into a photon at some point or will it just reach a certain threshold at which the whole thing is moving as fast as it will even if more thrust is provided?

How is time dilation not just a result of observation and perspective?
I really want an emphasis away from 'observation' and relativity because it seems like an endlessly arbitrary exercise in perspectives without actually illustrating what is happening to the matter and by what mechanism.

[Anonymous No.9628223]

>>9628197
You can get as close to lightspeed as you like.
All that happens in a particle accelerator is that it gets harder and harder to get even closer. The particles don't disintegrate. The particles have no idea they're moving close to lightspeed. From their viewpoint, they're not. They're stationary and the accelerator is rushing backwards.

Minkowski re-formulated SR in terms of geometry. Acceleration corresponds to "rotation" in space-time. It's not quite the same as simple rotation in space, because Minkowski space is hyperbolic, but there are analogies.

Imagine you and a friend are both surveying a country. You start at the same stop and begin measuring the locations of landmarks and noting their locations east-west and north-south of your starting point.
But you orient your maps so "up" is true north and your friend orients his so "up is magnetic north. All the landmarks will have different coordinates on the two maps.
But some things don't change. Both of you can measure the separation between two landmarks and you'll get the same answer. "Distance" is an invariant. In Minkowski space, "Interval" (whigh involves both time and space) is an invariant. Everyone agrees on it.
Nothing is really changing. Different observers simply measure space and time in different ways.
You can read a book on Special Relativity or watch some good videos. Give me a few minutes to look for some.

[Anonymous No.9628233]

>>9628223
https://youtu.be/1YFrISfN7jo
https://youtu.be/HUMGc8hEkpc
https://youtu.be/Cxqjyl74iu4
https://youtu.be/kGsbBw1I0Rg

[Anonymous No.9628373]

Is this just straight from Star Trek?

They specifically talk about warp field geometries and the thing oscillates.

[Anonymous No.9628392]

>>9628373
"Cochranes" are ST units.
Alcubierre got started because he was curious if anything like Trek was actually possible.
But I'm sure his papers never mention "Cochranes".

[Anonymous No.9628443]

>>9628233
>>9628223


Thank you for taking the time and effort.

It still seems "screwy".

Can something with no mass not move at the speed of light? Is anything with the property of 'no mass' always a photon?

I'd like to know more about converting mass into energy away from the whole speed, movement and distance frame of questioning.

The rod that is one light year long doesn't work because of causality right? Does this mean the particles do not push the others enough to break the rule and transmit information faster? The rod would still be moving for a year?

Also,
There is no absolute hot right? Couldn't the particles be vibrating and colliding too fast at one point and not go any faster and thereby hit an upper limit? Why is this not the case?

[Anonymous No.9628550]

>>9628392
Cochranes was named for the person who made and drove the engine, not the person who did the math.

[The Lord No.9628560]

>>9628373
what do millicochranes measure?

[Anonymous No.9628565]

>>9628560
Thousandth of a cochrane.

[Anonymous No.9628567]

>>9628443
Anything without "rest-mass" ALWAYS moves at lightspeed. So far, that's just light and gravitational waves.
Even things with infinitesimal masses (neutrinos have masses so small that we can't measure them) move slower than light. No time passes for a photon. They can't change. Neutrinos "oscillate" as they travel from Sun to Earth, so time must elapse for them and that means they're STL. (Though by very very little. The light from a supernova and the neutrinos from it arrive nearly simultaneously after crossing several million lightyears. The neutrinos actually come in a little early. They're not faster than light, but they escape the core of the dying star immediately, whereas the photons have to wend their way out of the catastrophe.)

The equivalence of mass and energy isn't difficult to prove. The usual example is based on the fact that light carries momentum. A flashlight "kicks back" a trifle. Photon rocket on a very small scale. That drains the batteries a little and they get lighter. Imagine a frame with a flashlight at one end and a photocell bank at the other. The photocells convert light back into electricity and store it in THEIR battery. During the time the photons were in flight, the reaction force on the flashlight moved it (and the frame) a little bit. Movement stops when the photons are absorbed and push on the photocells. Energy had vanished at end one and appeared at the other even though no atoms moved. The whole assemblage has moved a little bit. You know that you can't move the mass-center of a closed system. The mass-center must be right where it started. The only thing that moved was energy. So mass must be equivalent to energy.

The one light year rod doesn't work because the "push" is only transmitted atom-to-atom by electromagnetic forces. And they only propagate at lightspeed.
<continued>

[Anonymous No.9628575]

>>9628567
Particles pushed near lightspeed (in an accelerator or simply by heating them, manifest the energy as additional mass. The KE and momentum can increase indefinitely even if their speed hits a limit.

Watch more videos or read an introduction to Special Relativity book.

>>9628550
I know that. Zephram (spelling?) Cochrane built the first (human FTL drive.
He's not real and unrelated to Alcubierre (who IS real and who DID do the math.)

[Anonymous No.9628580]

>>9628567
Particles pushed near lightspeed (in an accelerator or simply by heating them, manifest the energy as additional mass. The KE and momentum can increase indefinitely even if their speed hits a limit.

Watch more videos or read an introduction to Special Relativity book. It makes perfect sense. It only SEEMS weird and contra-intuitive because we don't travel near lightspeed in our daily lives. I assure you, it's considerably LESS weird than quantum mechanics. ^_^
Try George Gamow's "Mr Tompkins in Wonderland". It'd old, but it illustrates what life would be like if the speed of light was only about 60 miles/hr. Makes it easier to visualize.

>>9628550
I know that. Zephram (spelling?) Cochrane built the first (human FTL drive.
He's not real and unrelated to Alcubierre (who IS real and who DID do the math.)

[Anonymous No.9628586]

>>9628567
Particles pushed near lightspeed (in an accelerator or simply by heating them, manifest the energy as additional mass. The KE and momentum can increase indefinitely even if their speed hits a limit.

Watch more videos or read an introduction to Special Relativity book. It makes perfect sense. It only SEEMS weird and contra-intuitive because we don't travel near lightspeed in our daily lives. I assure you, it's considerably LESS weird than quantum mechanics. ^_^
Try George Gamow's "Mr Tompkins in Wonderland". It'd old, but it illustrates what life would be like if the speed of light was only about 60 miles/hr. Makes it easier to visualize.

>>9628550
I know that. Zephram (spelling?) Cochrane built the first (human) FTL drive.
He's not real and unrelated to Alcubierre (who IS real and who DID do the math.)

[Anonymous No.9628588]

>>9628586
>He's not real
Neither are your posts.

[The Lord No.9628590]

>>9628565
nggg duurrrr

[The Lord No.9628603]

>>9628550
i think there was a lot of math involved in building a warp drive from post nuclear holocaust parts
>>9628586

[The Lord No.9628609]

>>9628603
oops

[The Lord No.9628629]

I still haven't worked through Alcubierre's paper but they say they major imperdiment to physical implementation is the need for a large reservoir of negative energy. Pic related, due to the complex phase normalization of the Modified Cosmological Model (MCM), and that the energy depends of the square of the field, Sigma- is a negative energy reservoir adjacent to spacetime. The negative energy is right there available at H where it would be needed for the Alcubierre drive.

For more about the MCM, check out my free book:
>The General Relevance of the Modified Cosmological Model
MIRROR 1: http://vixra.org/abs/1712.0598
MIRROR 2: http://2occatl.net/1712.0598v2.pdf
MIRROR 3: https://drive.google.com/file/d/1sXrFZhMo9OjoauL0SgAvpSxD_8qaAYi0/view?usp=sharing

[Anonymous No.9628636]

>>9628629
You again?
How many times do you have to be told your un-refereed ideas are fantasies?
Anybody can post any nonsense on vixra. They warn you about that right up front.

>>9628588
The physics is real.
Kept deleting to fix typing errors.

[Anonymous No.9628640]

FTL is for cucks, what we really want is some way to solve inertia, we could still have an interstellar empire with sub-light speeds

[Anonymous No.9628706]

>>9628640
Interstellar travel, OK
But did you mean "empire" literally?
"We're just received word that the colony on Aldebaran VIII has declared independence! Not to worry, sir. We can have troops there to put down the revolt in only 65 years -- and learn if they were successful in another 65."

[Anonymous No.9628734]

>>9627764
fortunately, negative mass was actually created

https://phys.org/news/2017-04-physicists-negative-mass.html

[Anonymous No.9628736]

>>9627647
What the fuck even is exotic matter? Is it another word for antimatter?

[Anonymous No.9628753]

>>9627644
>>9627644
>but there is also the alcubierre drive

Except that's also wrong.

/thread

[Anonymous No.9628760]

>>9627662
Well someone did essentially go over the math and improve it considerably, now you would only need a block of negative matter the mass of Jupiter to go a short distance.

Although they still haven't explained how to actually "land" at the destination without eviscerating the entire solar system you arrive at when all the matter that builds up on the bubble is released like a shotgun blast.

[Anonymous No.9628766]

>>9628000
>we'll never leave this planet as human beings.

Alright look, the rest was legit but that's a serious stretch. We'll leave this planet in our form, it won';t be easy but it's well within the realms of possibility.

[Anonymous No.9628782]

>>9628734
Notice that "negative mass" is in quotes.
It's like a helium balloon. Step on the gas and you're shoved back in your seat, but the balloon jerks towards the windshield.

>>9628736Exotic matter is not antimatter.
>https://en.wikipedia.org/wiki/Exotic_matter#Negative_mass
Mass and energy curve space in the Einstein equations. Lesser known is the fact that pressure also does it. Exotic matter would be capable of exerting so much outwards pressure that a "wormhole" could stay open despite the gravitational forces trying to close it. Mathematically, it's essential to all FTL and time-travel schemes.

[Anonymous No.9628809]

>>9628766
I have serious doubts about our physiology being capable of adjusting to outerspace conditions.
We are quite literally made for and by the circumstances on this planet. It might prove very problematic to the point of not being viable at all.

[Anonymous No.9628822]

>>9628809
Possible. But only way to find out is to try.
We'll see how many Muskenauts survive the trip and their first Martian year.

[Anonymous No.9628833]

>>9628809
That's totally unreasonable, I don't think there is a single issue that can't be resolved. Gravity can be replicated through rotation of any orbital habitats, we can ideally deal with radiation from using water for shielding and magnets.

I think we would have issues living on other planets but I think we could pull it off with O'Neill cylinders.

[The Lord No.9628847]

>>9628760
>need a block of negative matter the mass of Jupiter to go a short distance.

yeah but if you look at
>>9628629
you'll see how the size of the negative energy might not matter (so much) because the drive could be in contact with a negative matter-energy reservoir

[Anonymous No.9628868]

>>9627658
Didnt some nasa guy refined the model so that you only need a few tonnes of the stuff?

[Anonymous No.9628869]

>>9628782
So why are we investing our time into travel instead of wormholes? I'd imagine it won't take a planet worth of exotic matter to keep a wormhole open.

[Anonymous No.9628890]

>>9628868
yes true, Harold white his name was i think. but the problem is that how do we even extract or create negative energy? we could get to the point that it only needs the mass of a coffee mug but it still needs negative energy.

[Anonymous No.9628913]

>>9627979
the heisenberg gizmos were just things to evade the issue of transporters being either a cloning machine, or else requiring the murder of the person at the point of origin once their clone appears at the destination

[Anonymous No.9628915]

>>9628890
Just make the zero-point energy smaller you pleb

>but how-

You just have to locally reduce planck's constant so the vacuum energy gets smaller, OBVIOUSLY.

[Anonymous No.9628917]

>>9627647
I thought it was reworked to only require about 900kg? Still way more than we can get our hands on.

[Anonymous No.9628939]

>>9628068
Are you dyslexic too?

[Anonymous No.9628952]

>>9628183
so, at ftl, time is 'imaginary' (not negative for time travel), and so is the mass?

[Anonymous No.9628958]

>>9628550
named after johnny cochrane, who invented warped theories as OJ's lawyer

[Anonymous No.9628968]

>>9628706
the revolt will be easy to put down if the troops arrive at 1/2 speed of light and don't put on the brakes

[Anonymous No.9629001]

>>9628103
>You’re sitting somewhere right now. You’re not moving.
You're always moving, and even if you were on a spaceship, the graph would act the same since X and T represent spacetime from your frame of reference.

[Anonymous No.9629299]

>>9629001
You didn't read carefully.
No one considers themselves to be moving.
If you're not accelerating, your T axis is always a straight line between where you were and where you are. We don't disagree.

[Anonymous No.9629302]

>>9628706
Warp drives already solve it.

[Anonymous No.9629307]

>>9628913
How do you get around the uncertainty limit when scanning the location of all particles?
With the Heisenberg compensators.
And how do they work?
Very well, thank you.

Whatever, it's technobabble to get around the improbability of a gizmo originally introduced to speed up the action and save money.

[Anonymous No.9629312]

>>9628869
Well, first you have to create a wormhole (not easy. It's not just two black holes) and then you need exotic matter to stabilize it (and we don't have any of that at all) and then you have to drag one end of the wormhole somewhere you'd like to go to.

[Anonymous No.9629336]

>>9628952
In the real world, though imaginary numbers come up in the course of calculations, they always square out to produce real values for anything we can point at or measure.

Gerald Feinberg made a clever suggestion that there might exist particles (Tachyons) which had intrinsic imaginary mass. They could ONLY travel faster than light, so the imaginary parts would cancel and leave "real" masses going FTL.
It was quickly shown that, if it was possible to produce or detect them (and if you can't detect something, it might as well not exist) they could be used to send information back in time.
Later on, physicists found other flaws in the concept. Theories which include the possibility of tachyons always have probabilities which don't add up to 1. That's impossible. You run an experiment and you get an answer (or answers). You can't win a lottery more than 100% of the time you enter no matter much you cheat. So those theories are considered "diseased" and thrown away.

"Ordinary" particles moving at superlight speeds don't have sensible masses and times. It's like dividing by zero. You can do it, but the answers don't make any sense.

[Anonymous No.9629359]

>>9628640 was speculating on sub-lightspeed travel, if only there was a way around the fantastic amounts of energy required.
Ah, if only...

Reducing inertia would do it -- provided you also reduced gravitational mass at the same time and the "magic" wasn't noticed by the occupants of the ship. Some other fundamental constants would also have to change as well. Simply "annihilating inertia", like the Bergenholm in the Lensman stories would kill everyone instantly and probably destroy their very atoms.
Needless to say, we don't have the slightest notion of where to begin.


>>9628968 So the ships wouldn't have the energy required to crack planets.

>>9629302 You didn't bother reading the entire part of the thread you were replying to.

[Anonymous No.9629483]

>>9628128
Brace yourself, because I have the answer. It's the same as the answer to the smoker on a light speed train thought experiment. Everyone gets a series of events they agree with individuallly, but not together, because light has to travel at a certain speed to them all.

Instant movement is impossible, while FTL movement is not. FTL by warp drive creates a bubble around a ship that prevents it from communicating via EMR with the outside universe. A warping ship cannot communicate with Earth unless it turns off its warp drive and sends a regular transmission while moving at sub light speed.

But say you wanted to communicate with this stationary ship by sending a warp drive equipped drone out to meet it and return with a message.

The drone only appears to be sent back before it left by the ship out in space, because of it seeing the light lagged order of events from Earth conflicting with the drone arriving ahead of it. Likewise, Earth gets the drone back before it sees the ship receive the drone, but only because of light lag. It still gets the drone after it sent it, according to its own perceived order of events. From its world line, there's no reason to assume the drone will come back before it left. It will come back at some point after they send it.

[Anonymous No.9629492]

>>9628640
Warp drives already solve it. A warp drive incurs no inertia on the stuff within it, because the stuff experiences no felt acceleration.

>>9629359
It's that I didn't bother, I just sent you my reply by mistake.

[Anonymous No.9629558]

>>9628128

quantum entangled pairs can transmit information instantly. how does your scenario deal with this?

[Anonymous No.9629591]

>>9629483
If you cannot see in any way out of a warp bubble, how the fuck do you know to slow down?

[Anonymous No.9629594]

>>9629558
Quantum Entanglement does not transmit information

[Anonymous No.9629607]

>>9629483
Then you don't understand. The re-orientation of the X and T axes are real. It's unrelated to the lag of seeing distant objects.

If the drone reaches a ship receding from Earth at sublight velocity, matches vectors with the ship, and then (without any further acceleration) makes the Jump back to Earth, it will arrive in the vicinity of Earth (still with a high relative velocity) BEFORE it left Earth.

There IS NO WAY OUT!
The method used to go from A to B (acceleration, warp drive, hyperspace) is irrelevant, as is whether the craft can communicate during the process. Only the space-time coordinates of A and B and the direction of the axes matter.

Read >>9627974 and follow the link. Read any good book on Special Relativity or even a Wikipedia article. Physicists have been trying for over a century to come up with a theory which allows FTL yet forbids causality violations. (Real violations. Not just seeing the past because of lightspeed lag, but being able to alter the past.) No one has ever found a loophole. Even if the Alcubierre drive operated as predicted (and it should, IF we could produce the right metric) it allows travel into the past. Alcubierre says so, right up front.

[Anonymous No.9629614]

>>9629594
schroedinger's citation needed

[Anonymous No.9629624]

>>9629614
Quantum entanglement tells you that the string of random 1s and 0s showing up on Mars exactly matches the string of random 1s and 0s you have back on Earth. But you can't force any particular "bit" to be a 1 or a 0, so you can't send a message. It just looks random until you compare the two strings. And the comparison requires radio or something slower.

[Anonymous No.9629732]

>>9629591
You can see out of a warp bubble. At least the front, because light can come in that way. You can't send light forwards out of a warp bubble because it immediately gets squashed in front of the bubble. You can send some backwards, but you can't aim it, because a warp drive creates an event horizon behind you. There may or may not be some Unruh radiation involved which could scramble everything, though.

[Anonymous No.9629746]

>>9629607
Why must the drone suddenly become detached from the world line of earth and form with the world line of the ship it visits? It doesn't have to. That's how I see it. It's all just light lag and the smoker on a train thought experiment comes into play.

[Anonymous No.9629837]

>>9629624
Maybe, maybe not. What we do know is that there is something connecting these particles. Something that is transcending distance. What could it be? We don't know.

I think it's probably some particle that moves backwards through time. Some people say that there is only one electron in the universe and it's constantly moving backwards and forwards in time like a bending river.

[Anonymous No.9629955]

>>9629837
You can take that idea and put it in the trashcan where it belongs

[Anonymous No.9630039]

>>9629955
Which idea? I stated at least 2.

[Anonymous No.9630045]

>>9627644
Interstellar Travel is a LOT Harder than
Curing Cancer or Going to Mars.

Just saying.

[Anonymous No.9630049]

>>9627644
Elon Musk is spending decades to go to Mars. NASA is even slower.

At this pace It will take centuries to get the technology to even go to the nearest exoplanet.

[Anonymous No.9630057]

>>9629607
No, you don't understand. I have looked up the question for last coulpe hours and the answer that all those youtube professors and PBS space time say is; no, you cannot use FTL to affect past events in your own world line. Whenever you attempt to return in some way to your original destination, time will catch up with you until it becomes the present just as you land. Furthermore, it's suggested that any type of time travel that attempts to create a paradox is impossible. Not that you can't try, but that doing so will always result in some spontaneous event that stops it from happening. Your time vehicle explodes, turns into a black hole, or you just randomly die before you can convey info or perform a paradoxical action. Sort of like a schodingers cat scenario where the cat can never be found alive. Or a spinning coin that will refuse to land on heads if that would create a paradox- it just keeps spinning until a quantum fluctuation makes it land on tails.

[Anonymous No.9630343]

In >>9627839 I said the interior of a warp bubble is “causally disconnected” from anything outside. You can’t see or steer or stop.
>>9627861 protested that was ridiculous. Just turn off the engines! It’s a very good argument with no immediate answer.

Think of a black hole. What becomes of objects which have fallen through the event horizon? They could be square dancing inside. They could have vanished, teleported to a literal Hell of brimstone lakes and demons with pitchforks. The smart money is they keep falling until they’re stretched and crushed and destroyed by the Singularity – but we don’t know for sure. Watching from a distance we can never know.

Suppose the matter really vanishes, to Hell or some other cosmos or even some distant part of our own universe. It’s gone and so is its gravitational field. Why is the event horizon still there?

Mass and energy curve spacetime. Any mass and energy. Curved spacetime (a gravity field) represents energy. Which means gravity has gravity! This non-linearity is what makes the Einstein equation so hard to solve (compared to electromagnetism).

Things inside the event horizon are causally disconnected from the outside. They’re no longer needed. A black hole (classically, no quantum effects) is self-sustaining, as is a propagating electromagnetic wave. Once formed, it's permanent. An Alcubierre bubble is just another metric. It takes energy to create, but none to sustain. The engines don’t run continuously.
<continued>

[Anonymous No.9630346]

>>9630343
Well, why not generate a counter-field to escape? I’ll have to explain with an analogy. If you yell, your voice spreads in all directions at the speed of sound --relative to the air. If there’s a breeze, your shout goes downwind faster than it goes upwind. It you scream in a supersonic wind tunnel, your cries don’t go upwind at all. No one in that direction will ever hear you.

The “cancellation” field is a distortion of the metric and, like all gravity waves, it propagates at lightspeed. It can never reach the boundary of the warp. In “flat” space we can move in any direction we like – but only forward in time. At a hole’s event horizon, the metric changes. You can move freely in time but only “forward” in space – in the direction leading to the Singularity and destruction. There’s no way out.

[Anonymous No.9630359]

>>9630057
I understand. And I think you do too. You're just looking at it backwards.

If you have FTL then you can travel backwards in time. You protested that you can't change the past. Some effect or another will prevent this.

I agree. That means the initial assumption -- FTL travel is possible -- was false.
There are no paradoxes in the real universe.
No FTL, no paradox.

The likeliest scenario is simply that FTL drives don't work or there's no negative energy or whatever.
If you prefer to imagine that FTL drives can be built -- but the ship explodes or falls into a black hole or you randomly die when you try to turn it on -- that's fine with me.

[Anonymous No.9630369]

>>9627644
The entire concept is based on something that doesnt exist. It's a bigger meme than EMdrive.

[Anonymous No.9630382]

>>9629746
The drone isn't "detached" from Earth.
By accelerating to match the sub-light ship it has changed its inertial frame and re-oriented its X and T axes.
Does it have to?
No. It could remain stationary with respect to Earth, communicate with the sub-light ship via radio, and then return to Earth AFTER it initially left.
No problem and no paradox.

But it COULD carry out the maneuvers described earlier and return before it left.

The ansible case was simpler because the unit is already aboard the sub-light ship.

The only way to avoid backwards time travel in a universe with FTL is to assume that you can never change your inertial frame, never accelerate. Since we're pretty sure it IS possible to accelerate objects, we can always create a contradiction.

[Anonymous No.9630529]

>>9630359
There's no reason you can't travel to the past if you aren't creating a paradox. Time travel that creates no paradoxes is permissible.

[Anonymous No.9630536]

>>9630346
The event horizon in the back of a warp drive bubble contains no singularity behind it. Just the half of the universe that's behind you. Supposing you go through it, all you do is escape the bubble. Not like you can't just go out the sides or something, anyway. It is not a true event horizon and I don't think it should be called one.

[Anonymous No.9630573]

>>9630529
Fine.
How do you avoid creating paradoxes?
It doesn't have to be shooting Hitler. Stepping on a butterfly will do.

OK, the universe branches and you're on a different time-track. Doesn't matter if you kill your grandfather. He still lives in the history which led to "you". You just can't "go home" again.
It's an "out", but it also means you never return from an interstellar trip to the same world you left. That's not your wife and those aren't your kids no matter how similar they appear. (I've read stories where they're not similar at all. Or where your doppleganger never joined the Space Force, never took that flight, and is still living in your house.)

>>9630536
Call it what you will.
From what I've read of the Alcubierre drive and from what I understand of the math, "causal disconnection" means exactly what its name says.
There's no singularity anywhere, but just try to imagine a one-way surface with an "edge". That is, it doesn't form a complete enclosure.

It's like trying to draw magnetic field lines (I know they're not real, but they offer non-mathematical insight into the problem) which don't form complete loops. Topological impossibility. In Relativity, the metric has to vary "smoothly" (which is why it can't handle quantum-discontinuities.)

[Anonymous No.9630578]

>>9630382
I don't agree with that. Think of it another way. What if there is no ship to communicate with but the drone makes the trip anyway? From the drone's perspective, the drone leaves, turns around and comes back to say the ship has vanished, in that order. Things look weird on Earth if people try to watch the drone for the full trip, but it will still come back after it left. There's no violation there, even if the drone puts the warp drive into 5th gear and returns instantly. It still cannot return to earth's world line before it left. So why would or should there suddenly be a paradox if there was a ship to communicate with? The answer is there wouldn't be.

[Anonymous No.9630585]

>>9630573
>How do you avoid creating paradoxes?

One way trips is an example. Doesn't matter when or how fast you arrive at Proxima centuri. If you only arrive once, you aren't messing with anything.

[Anonymous No.9630587]

>>9630578
We'll assume 5th gear (infinite speed) all the way to make the diagrams easier to follow. But it works even in 4th gear.

In your picture, the drone leaves Earth at 3 and Jumps to 2. It then turns on its rockets and accelerates away from the Earth to, say, half lightspeed.
Then it Jumps back to Earth along it's X-prime axis and arrives at 1.

The slower-than-light ship was only needed to carry the ansible. If there are FTL drones (or manned ships) then the STL ship isn't necessary.
FTL plus the ability to change inertial frames = time travel.

[Anonymous No.9630601]

>>9630585
But nothing (no physical law, anyway) keeps you from going home.
Physics should not depend on what humans decide to do.

If time travel is possible and no one in all of time or space opts to push the button, there are no paradoxes then either. But that's an inane way to build a universe.
Might as well posit a perpetual motion machine which doesn't break energy conservation so long as it's not started.

I can give you another example. Dirac proved that the possible existence of a magnetic monopole, even one, anywhere in the universe, requires the quantization of electric charge. The fact that charge is quantized doesn't mean there's a monopole out there somewhere. The big bang might not have created any and we might never do so either. But the mere POSSIBILITY they could exist would automatically constrain physical laws.

[Anonymous No.9630624]

>>9630573
I call it a false horizon. It exists only to the ship while the ship is forcing space to contort to form the warp field that is moving the ship and only while the shit is moving at FTL. But space does not want to do this twister act. Space wants to be smooth. Therefore the field requires constant energy to maintain itself and fight the smoothing force of space. Turn the energy source off and the field will destabilise. Energy has gravity, but the back of the field is essentially anti gravity and it will want return to normal. It's not a kugelblitz black hole kind of situation. The false horizon will disperse as the smoothing effect of space acts as a form of drag on the warp bubble.

[Anonymous No.9630652]

>>9630587
As soon as the drone stops going FTL via warp it will essentially be at zero velocity relative to earth, and it will immediately start moving forward in time, up the graph, etc. Whatever it needs to do to set up some conventional speed relative to Earth, it should require enough time that it can only ever return to earth at a point after it has left.

I believe the universes supposed anti paradox rule comes into play if this is not the case. Remember that warp drives release powerful blasts of photons when they are turned off. If the drone tries to go straight back to earth, everything is destroyed by the cone of light and the fact that the drone is moving at 0.5C relative to earth even without the warp drive. So if the drone needs to fly back on a tangent and stop while facing away from earth to release the photon cone, then accelerate to match earth's speed, then return to earth normally, that takes lots of time. Enough that it would again only be able to return after it left if it wants to remain intact and preserve the earth.

[Anonymous No.9630657]

>>9627644
Was this the other form of the meEM drive, or the one requiring exotic (read: negative mass) materials?

[Anonymous No.9630676]

>>9630624
I can't prove you wrong.
But I've never seen any physicists (including Alcubierre) who agree.

Space may indeed "want" to be flat, but classical black holes don't vanish and I don't see why this should be different. You're still insisting there has to be a "null" line between attraction and repulsion where the curvature goes to zero. The standard illustrations show the potential surface "depressed" in front and "raised" in the rear, but that's only a two-dimensional analogy.

I'm sure complete analyses must exist but, as I said, I haven't seen any which take your side.
I'm trying for realism, not negativism. Please post a link if you can find one saying such a field can be shut down.

In any case, the issue is probably moot since we don't have anti-gravity or negative mass.

Relativity can be tricky.
Ever hear of Frank Tipler?
Look up the link in the image. If I try to post it directly, 4Chan blocks it as Spam. :(

A rapidly rotating cylinder with a density comparable to that of a neutron star would "drag" the frame around it and make FTL and time travel possible.
Tipler could only solve the math for the case of an infinitely long cylinder but figured that was good enough. If the cylinder was, say, a light year long and only a few meters in diameter, what difference did the ends make? It's like we can ignore the curvature of the Earth when putting up a skyscraper. "Vertical" lines are parallel anywhere on the building site.
Well, re-analysis showed Tipler was wrong (and some pretty good SF stories went down the drain.) If there are ends, however distant, it doesn't work.
Relativity can be very sensitive to "boundary conditions."

[Anonymous No.9630702]

>>9630652
Again, this means physics depends on the actions of human beings -- a desire not to fry the Earth. Reality doesn't work like that.
Anyway, you don't have to go straight back to
Earth. You can aim "close" but far enough to miss, and pass information on by radio.
The longer the hyperjump or the larger the change in inertial frames, the farther back you can go. There's no limit. A million years if you like. Plenty of time to match velocities. There's no limit on acceleration (especially if it's a drone with no passengers to be crushed.)

I can't keep shooting down ideas indefinitely. I wish the people who believe FTL is possible (without allowing causality violations) would read up on Special Relativity.

>>9630657
Shawyer's Emdrive is BS. His "theory" is full of contradictions.

The Alcubierre drive is a valid solution to the Einstein equation. It would work -- IF we could create the proposed metric. Doing so would require exotic (read: negative mass) materials.

PopSci writers who conflate the two ought to be shot!!

[Anonymous No.9630712]

>>9630702
I was by no means saying that the two are similar, but AFAIK there is another meme drive similar to Shawyers, and I wasn`t sure if that was it (I am really bad with names).

[Anonymous No.9630914]

>>9630712
Oh, yes. The Cannae drive.
Now that you know the name, you can find it on-line.

You'll also get a lot of James Doohan jokes where he's saying "She cannae take any more, Captain. She's gonna blow!"

[Anonymous No.9630920]

>>9628809
>We are quite literally made for and by the circumstances on this planet

no. but we are pretty adaptable.

https://i.4cdn.org/tg/1521935420088.pdf

[Anonymous No.9630924]

>>9630624
Just a few final (??) observations;

Gravity fields don’t “run down”. It costs the Earth nothing to maintain its field. If space “wants” to flatten out (revert to a minimum energy configuration) it’s certainly not making much progress.

Every single article you’ve ever read about the Alcubierre drive talks about the energy required to establish the field. Because the numbers are so stupendous, they’re usually given in terms of mass-equivalent. Depending on assumptions and exact configuration they range from “more mass than exists in the entire universe” down through “Jupiter” and down to “a few hundred kilograms”. And they all require exotic matter.

But they all talk of “energy”. Never “power”. How much you have to keep feeding in to maintain the condition. Never “0.1 Jupiters/second”. That certainly suggests that the field is stable and self-sustaining, does it not?
<continued>

[Anonymous No.9630928]

>>9630924
The warpfield may be a very unusual metric, but it’s still no more than a fancy gravity field. As such, it has a potential associated with every point. And going from Point A to Point B may require or release energy, but the amount is always path-independent. If you’re forbidden to go from “inside” the field to “outside” the field by one path, you’re forbidden to go by ANY path. If the warp is inescapable “forwards”, it’s equally impossible to sneak out through the “back” or the “sides”.

Gravity is conservative.
Imagine a sheet of Cavorite, the gravity insulator. Simply step onto it and float into space. If such a material existed you could shove a boulder into the zero-gee area, let it rise, then shove it out and let it fall and do work. “Free energy”.

To avoid this, it must be impossible to step onto a sheet of Cavorite. Well, almost impossible. There has to be a force resisting you taking that step. It requires the same energy as climbing 4000 miles straight up, but you have to exert that force over only the space of a few inches, so it’d be like struggling through an (almost) impenetrable force-shield. Contrawise, if you were weightless and got too close to the edge, you’d be ejected violently – propelled outwards at 7 miles/second.

[Anonymous No.9631647]

>>9627644
still a fiction

[Anonymous No.9631932]

>>9630676
You are pretty much the first time I've seen a person claim that a problem with a warp drive would be turning it off. Everyone else mentions Unruh radiation from the false horizon frying the ship, or the photon blast that would happen upon turning it off destroying the destination. I don't think stopping the warp drive is impossible. Either a ship's position within the center of the warp bubble is unstable (like the L1 lagrange point between the earth and sun) and easily escapable, or it's possible to dissipate the field with countering forces by the warp drive. You said the second point was not possible because gravity waves travel at light speed, but that seems like a null argument when the whole point of the drive is to go above and beyond that threshold.

[Anonymous No.9632023]

>>9631932
Not original with me.
The "causal disconnect" has been raised often in technical papers about the drive.

https://physics.stackexchange.com/questions/13444/getting-back-out-of-an-alcubierre-warp-bubble

Your final point is not valid because nothing within the warp bubble travels faster than light. It's the volume which is supposed to be moving FTL. Inside, you supposedly feel nothing. No acceleration, no relativistic effects, and no change in lightspeed. Space is supposed to be "flat" on the inside. All the extreme curvature is at the boundary.
(It's important to keep conditions "normal" on the inside since any change in the laws of physics would probably kill you in an instant.)

[Anonymous No.9632037]

>>9632023
>Your final point is not valid because nothing within the warp bubble travels faster than light.

Aside from another warp bubble.

[Anonymous No.9632068]

>>9632023
That's not a technical paper, it's bloody stack exchange. Furthermore the guy in the thread who uses the phrase himself goes on to say, "But there is no reason it cannot be affected from an outside agency at a pre-planned points, or even simply have a finite lifetime, naturally deteriorating to stop at the intended destination."

The thread is full of people saying the how the bubble can be stopped through means such as dissipating the exotic matter that upholds it, too. Only the dude who made the thread thinks it can't be escaped and his argument is some bullshit analogy about jumping over scrunched rubber. He misses the point that the bubble is moving, too.

[Anonymous No.9632526]

>>9628109
The diagram is a trick. You constructed that time travel path using 2 different reference frames. Earth's, and a half lightspeed frame. Normally, that would be fine, because spacetime events marking different stages of a sub-lightspeed journey make consistent Lorentz transformations between themselves. However, when we introduce FTL travel, things get messed up. Superluminal paths aren't real worldlines. Real worldlines don't point backwards in time under Lorentz transformations. While we can define a chain of events that looks like an FTL journey, these aren't paths that real objects can take.

[Anonymous No.9632965]

>>9632068
You are right. This is not a technical paper. I couldn't find any on-line on short notice.
But they're out there if you hunt and the great majority cite causal disconnection.

>>9632526
Also right.
The diagram shows what could be done IF superlight travel was possible.
Quoting you, "these aren't paths that real objects can take"
Which means the initial assumption was wrong and FTL isn't possible.
I was demonstrating "reductio ad absurdum" and you appear to agree with me.
Alcubierre paper (though non-technical)
>http://ccrg.rit.edu/files/FasterThanLight.pdf
states that any scheme (including his own) has to deal with causality problems.