# Thread: Impossible FTL

1. ## Impossible FTL

I named this thread "impossible FTL" because I think this is more of a physics question than anything to do with actually going faster than the speed of light. If this thread needs to go someplace else, please move it. This is more of a flight of fancy than anything else. I thought of it for a story, but it's a rather dumb story. So, it won't even be used for that.

In this scenario, two ships are traveling at ridiculous speeds, a high percentage of the speed of light. Let's call them "The Leader" and "The Chaser". The ships have a problem, they are pretty much the same except for the crew. They are accelerating at the same rate, so the gap between the ships cannot be closed. This chase has been going on for a long time and everyone finds it frustrating to be stymied by technology and physics.

The crew of The Leader comes to the conclusion that relativity isn't real and believe they can tap energy from outside the ship (another place, another dimension, magic, whatever.) to accelerate to FTL speeds. They are correct that they can tap that energy, but the ship can't take the acceleration and breaks up. Someone forgot to carry a one or something, I guess.

Would The Chaser momentarily feel a pull from all of that extra energy/mass coming from the other ship?

2. Originally Posted by Solfe
I named this thread "impossible FTL" because I think this is more of a physics question than anything to do with actually going faster than the speed of light. If this thread needs to go someplace else, please move it. This is more of a flight of fancy than anything else. I thought of it for a story, but it's a rather dumb story. So, it won't even be used for that.

In this scenario, two ships are traveling at ridiculous speeds, a high percentage of the speed of light. Let's call them "The Leader" and "The Chaser". The ships have a problem, they are pretty much the same except for the crew. They are accelerating at the same rate, so the gap between the ships cannot be closed. This chase has been going on for a long time and everyone finds it frustrating to be stymied by technology and physics.

The crew of The Leader comes to the conclusion that relativity isn't real and believe they can tap energy from outside the ship (another place, another dimension, magic, whatever.) to accelerate to FTL speeds. They are correct that they can tap that energy, but the ship can't take the acceleration and breaks up. Someone forgot to carry a one or something, I guess.

Would The Chaser momentarily feel a pull from all of that extra energy/mass coming from the other ship?
Accelerating to FTL violates what light speed means. You can't get there from here. If you posit a regular acceleration from .99 C to .999 C, that makes more sense physically, and still fits the scenario of the chaser ship being damaged (or more likely, the crew being crushed).

3. The fundamental question behind all this seems to be: "Does energy have gravitational mass?"
Yes.

Grant Hutchison

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## A Kilometer?

Originally Posted by Noclevername
Accelerating to FTL violates what light speed means. You can't get there from here. If you posit a regular acceleration from .99 C to .999 C, that makes more sense physically, and still fits the scenario of the chaser ship being damaged (or more likely, the crew being crushed).
The distance between the ships has not been specified.

5. Originally Posted by John Mendenhall
The distance between the ships has not been specified.
The rest mass of the Leader has not been specified. The amount of energy mysteriously acquired by the Leader has not been specified. The gravitational acceleration implied by "feel a pull" has not been specified. I don't get the feeling the OP is a quantitative question.

Grant Hutchison
Last edited by grant hutchison; 2020-Oct-21 at 12:50 PM.

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Well, if it's a chase, then can we assume Chaser started at some point after Leader? If so, while accelerating, the distance between them grows. That could add a twist to the story.

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## The Boundary Conditions Need To Be Defined

Originally Posted by 7cscb
Well, if it's a chase, then can we assume Chaser started at some point after Leader? If so, while accelerating, the distance between them grows. That could add a twist to the story.
Many good points.

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E=MC2 so a whole lot of energy equals very little mass

so if the first ship is totally converted to energy the resulting energy's gravity is no greater then the ships rest mass/gravity

and would be no net change to the second ship's speed as the mass/gravity of the first ship stays the same when converted to energy/gravity
at the time point the first ship converted to energy

now at a later time point as the energy expands some radiation would impact the second ship slowing it very slightly

9. Originally Posted by nota
so if the first ship is totally converted to energy the resulting energy's gravity is no greater then the ships rest mass/gravity

and would be no net change to the second ship's speed as the mass/gravity of the first ship stays the same when converted to energy/gravity

at the time point the first ship converted to energy
I believe the OP intends the Leader to have gained energy, from some magical realm, which leads to its destruction. I may be wrong.

Grant Hutchison

10. Originally Posted by John Mendenhall
The distance between the ships has not been specified.
What does that have to do with my post??

11. Okay, this is how I visualise this. Two ships, accelerating off into the Visible Universe, maybe both using some kind of Bussard Ramjet. Larry Niven wrote a short story with a similar premise; The Ethics of Madness, which assumes that some of the problems of the ramjet concept have been ironed out.

No matter how much matter these two ships collect and convert into thrust, they will never exceed the speed of light. But maybe the lead ship has a genius scientist on board, who finds a way to tap into the energy of other nearby universes. Maybe one of the nearby branes is young enough to still be in the unification era just after the Big Bang, and energy could be extracted from such a cosmos just like tapping a hole into a high-pressure water main. Whoosh!

Even if the entire energy of such a universe could be directed into the propulsion system of the lead spacecraft, this still would not be enough to break the light barrier. But it should easily be enough to destroy the lead spacecraft in a burst of energy. I'm sure that the chaser spacecraft would be able to detect this detonation in due course, assuming the luminosity of the detonation is sufficiently brilliant. You might even get a detectable gravity wave, but I doubt if they could 'feel' it in any meaningful fashion.

12. Originally Posted by nota
E=MC2 so a whole lot of energy equals very little mass

so if the first ship is totally converted to energy the resulting energy's gravity is no greater then the ships rest mass/gravity

and would be no net change to the second ship's speed as the mass/gravity of the first ship stays the same when converted to energy/gravity
at the time point the first ship converted to energy

now at a later time point as the energy expands some radiation would impact the second ship slowing it very slightly
I think if you read the original post, the scenario is that the first ship is gaining some energy/mass from some external source ("tap energy from outside the ship"). So there would be a net change. Whether that's possible or not is a different question, I'm just mentioning that that is the thought experiment.

13. This seems like one of those mathematical story problems where they intentionally throw in information you don't need so the first step is to figure out what the extra is and ignore it. Things that don't seem to have an effect on the question & answer include the fact that the two ships are moving, how fast they're moving, why they're doing that, the issue of the impossibility of exceeding c, the destruction of one ship, the mistake by one ship's crew regarding that impossibility, and even the fact that they're ships (although I guess we had to have our observers in some kind of setting to observe from).

That leaves us with two objects/observers, one of which begins increasing energy/mass, and the question of whether the other observer would detect an increase in gravity. The answer is that there is an increase in gravity but its detectability depends on how much it's increasing, how far apart the two things are, and the sensitivity of their method of detecting changes in gravity. If you had numbers for those things, you could calculate whether the increase in gravity at the second observer's location was above or below the detectability threshold with simple algebra, which means, as the author of this fiction, you can make up numbers to yield whichever result you want for the story. So, on the level of just bare basic principles, yes, it could be detected.

14. Originally Posted by John Mendenhall
The distance between the ships has not been specified.
I'm really sure that I am not qualified to name a number. What I am picturing is rather cartoonish, to be quite honest.

The scenario I am picturing is a working two ships with something close to or approximating a functional Bussard ramjet. Which, to my understanding is sort of a dicey proposition. We happen to live in a region where this really can't work at all, and in other regions of space it probably should have problems with drag. But there it is.

Let's say the distance is 10 light seconds and see what happens.

Reading ahead to Grant's observation, I don't have a rest mass for either ship. Where I want to make wiggle room for myself is The Leader suffers a catastrophic event due to the magical ability to draw energy from someplace outside the ship or the immediate detectable environment around the both ships and their trajectories. Having invoked a magic engine from the start, the energy brought on board is sufficient to cause failure of any structure of reasonably normal material on The Leader. It's not made of exotic substances that anyone knows of. They have a couple of handwaves to be doing what they are doing, but material strength isn't one of those handwaves. The Chaser is in trouble from the fact that other ship has suddenly stopped accelerating.

Grant is correct that the demise of The Leader is caused by a dramatic increase in energy and resulting mass.

Circling back to Clever's post, I think John was asking me. But to directly address you question and thoughts on the matter (Hey! A terrible pun.) , yes everything you say is correct. The crew of The Leader has made a logical mistake and is not acting entirely reasonably. They have correctly devised a way to get more energy that they should have by any rights, but it doesn't help them one bit. Not only is the idea wrong, their basic understanding of engineering is being ignored when they decided to tap that power source. Their ship breaks apart under the stress. They have zero chance of going faster than the speed of light. They just took on a large amount of energy and mass to no effect.

The main question is, could The Chaser have some sort of instrument that could detect a sudden change in mass by The Leader. Personally, I'd like to be a force that the crew could directly sense (and survive) but maybe that can't happen at all.

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## The Lead Ship Should Be Naned "Nova"

Originally Posted by Noclevername
What does that have to do with my post??

If the relativistic increase in mass produces an increase in gravitational forces then the gravitational forces felt by the chaser are highly dependent on the distance to the leader.

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## Best In A While

Originally Posted by Solfe
I'm really sure that I am not qualified to name a number. What I am picturing is rather cartoonish, to be quite honest.

The scenario I am picturing is a working two ships with something close to or approximating a functional Bussard ramjet. Which, to my understanding is sort of a dicey proposition. We happen to live in a region where this really can't work at all, and in other regions of space it probably should have problems with drag. But there it is.

Let's say the distance is 10 light seconds and see what happens.

Reading ahead to Grant's observation, I don't have a rest mass for either ship. Where I want to make wiggle room for myself is The Leader suffers a catastrophic event due to the magical ability to draw energy from someplace outside the ship or the immediate detectable environment around the both ships and their trajectories. Having invoked a magic engine from the start, the energy brought on board is sufficient to cause failure of any structure of reasonably normal material on The Leader. It's not made of exotic substances that anyone knows of. They have a couple of handwaves to be doing what they are doing, but material strength isn't one of those handwaves. The Chaser is in trouble from the fact that other ship has suddenly stopped accelerating.

Grant is correct that the demise of The Leader is caused by a dramatic increase in energy and resulting mass.

Circling back to Clever's post, I think John was asking me. But to directly address you question and thoughts on the matter (Hey! A terrible pun.) , yes everything you say is correct. The crew of The Leader has made a logical mistake and is not acting entirely reasonably. They have correctly devised a way to get more energy that they should have by any rights, but it doesn't help them one bit. Not only is the idea wrong, their basic understanding of engineering is being ignored when they decided to tap that power source. Their ship breaks apart under the stress. They have zero chance of going faster than the speed of light. They just took on a large amount of energy and mass to no effect.

The main question is, could The Chaser have some sort of instrument that could detect a sudden change in mass by The Leader. Personally, I'd like to be a force that the crew could directly sense (and survive) but maybe that can't happen at all.
It's a good thread, Solfe. Lots of fun with an impossible idea. Thsnks, John.

17. Originally Posted by John Mendenhall
If the relativistic increase in mass produces an increase in gravitational forces then the gravitational forces felt by the chaser are highly dependent on the distance to the leader.
Yes, and what does that have to do with my post?

ADDED: Oh, I see I wrote chaser when I meant leader. OK.

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## Lemme See Now . . .

Originally Posted by Noclevername
Yes, and what does that have to do with my post?

ADDED: Oh, I see I wrote chaser when I meant leader. OK.
Got it. Now, I put a big "If" at the start of my post because I couldn't remember if the relativistic mass increase produced an increase in the percieved gravity of the leader for the external observer, in this case, the chaser?

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## Oh My God Ship

You might be able to get rid of some of the 'magic' if the two ships are headed towards Ursa Major to investigate the potential 'warm spot' source of the 'Oh My God Particle' (link is here: https://en.wikipedia.org/wiki/Oh-My-God_particle), if whatever accelerated the particle gets a hold of the ship.

20. Originally Posted by John Mendenhall
Got it. Now, I put a big "If" at the start of my post because I couldn't remember if the relativistic mass increase produced an increase in the percieved gravity of the leader for the external observer, in this case, the chaser?
It should. Damage done depends on the exact amount of energy the other vessel picks up, as well as distance and relative difference in acceleration. Too much energy would simply vaporize the energized ship, which could radiate enough to fry its companion.

Either way, it's probably bad news for the one trying to jump ahead. Mother Nature doesn't play nice with physics violations.

21. The reason I find this question interesting is the human factor. When I picture a starship, I am imagining that the thing is big. But maybe it has a relatively small crew. How small, I don't know? From a dozen to hundreds, but probably not 1000. As a writing exercise, it's sort of like a flying dinner party. You can't describe that many people.

The skills needed to operate the ship are probably not exactly the skills necessary to determine if someone wrote a weird physics paper full of "hoo-ha" or some groundbreaking new theory. Wherever the ship is, they don't have the capacity to get an outside opinion from home. The Chaser might be having the same sort of "intelligence breakdown" as the crew of The Leader, but perhaps it expresses itself in a way that is not germane to the current situation. Maybe they waste resources on Cosplay festivals or movie productions. People can go "strange" in nearly an infinite number of ways.

This almost sounds like a generation ship or extreme one life-time flight, so maybe you did have a really sharp crew but now you don't. Perhaps the ship itself has degraded over time. It should be ok, but in a fantastic scenario, it isn't because no one thought it was possible.
Last edited by Solfe; 2020-Oct-22 at 10:47 PM.

22. Originally Posted by Solfe
This almost sounds like a generation ship or extreme one life-time flight, so maybe you did have a really sharp crew but now you don't. Perhaps the ship itself has degraded over time. It should be ok, but in a fantastic scenario, it isn't because no one thought it was possible.
If the crew has stopped routine maintenance or the vessel has started to degrade at relativistic speeds, it's not long for this Universe anyway.

As far as tapping energy for an "impossible" boost, it would require them to have the capacity for inventing new technology using only onboard resources and brainpower. So yes, "hoo-ha" physics.

23. The extra mass-energy gained by The Leader might be detectable by a so-called Forward Mass-Detector; not called that because it points forward, but because the principle was devised by Robert Forward.
https://en.wikipedia.org/wiki/Robert..._Mass_Detector
These are supposedly quite difficult to use, but if the extra mass-energy gathered by The Leader is sufficiently spectacular, a suitably modified FMD might pick it up.

24. Originally Posted by eburacum45
The extra mass-energy gained by The Leader might be detectable by a so-called Forward Mass-Detector; not called that because it points forward, but because the principle was devised by Robert Forward.
https://en.wikipedia.org/wiki/Robert..._Mass_Detector
Little known factoid about Robert Forward: in addition to physics, he was a rugby enthusiast, and he invented a technique that was ultimately rejected but adopted by the American version, becoming American Football: the Forward pass.

25. Originally Posted by Noclevername
As far as tapping energy for an "impossible" boost, it would require them to have the capacity for inventing new technology using only onboard resources and brainpower. So yes, "hoo-ha" physics.
Yes, the OP specified that this was just a thought experiment, and it might happen even "by magic."

26. Originally Posted by Jens
Little known factoid about Robert Forward: in addition to physics, he was a rugby enthusiast, and he invented a technique that was ultimately rejected but adopted by the American version, becoming American Football: the Forward pass.
*groan*

27. As for an ending for this scenario, The Chaser can probably build a spare engine from spare parts. The only way to "dodge" the debris from The Leader is to deliberately weaken the engine struts and turn hard enough for the ship to snap at a specific time and place. The engine roars into the debris while the crew section is flung off at wild angle. It's not pretty, but it works so long as the story ends before they try to make a new engine out of spare parts on a horribly damaged hull, it's a type of closure.

The impetuous to write such a beast is make something fantastic momentarily plausible and in the final review, the fantastic detail isn't what would be expected. No one actually goes faster than the speed of light, but they seem to do something equally inexplicable.

If I wanted to make a sequel, which did occur to me, it would be based on two crewmen from The Chaser who needed to sacrifice themselves by remaining in the engine compartment. After they die, they wake up back on Earth locked up in very strange facility. It slowly becomes apparent that they are AI's and have personally experienced the consequences of speed of light "travel". A final signal from The Chaser triggered a computer to activate their backup copies back home. That tidbit confirms that nothing goes faster than the speed of light and explains why no one tried to come up with a plan to not sacrifice a portion of the crew. They resided in the engine compartment and really couldn't be saved.

Since they have first hand experience of something that should be impossible and that knowledge killed a bunch of people, they do their best to hide it from people back on Earth. It's a cross between a murder mystery and accident investigation. It could get even weirder than the first story if these two AI programs start to imply that everyone on the ship was an AI and not a physical person. In this case, the broken trope isn't magical energy gains or FTL travel, but AI's so advanced they are indistinguishable from humans. Including lapses in reason and logic. An AI that can fool itself into not doing math is a pretty strange creation.

28. Originally Posted by Solfe
As for an ending for this scenario, The Chaser can probably build a spare engine from spare parts. The only way to "dodge" the debris from The Leader is to deliberately weaken the engine struts and turn hard enough for the ship to snap at a specific time and place. The engine roars into the debris while the crew section is flung off at wild angle. It's not pretty, but it works so long as the story ends before they try to make a new engine out of spare parts on a horribly damaged hull, it's a type of closure.

The impetuous to write such a beast is make something fantastic momentarily plausible and in the final review, the fantastic detail isn't what would be expected. No one actually goes faster than the speed of light, but they seem to do something equally inexplicable.

If I wanted to make a sequel, which did occur to me, it would be based on two crewmen from The Chaser who needed to sacrifice themselves by remaining in the engine compartment. After they die, they wake up back on Earth locked up in very strange facility. It slowly becomes apparent that they are AI's and have personally experienced the consequences of speed of light "travel". A final signal from The Chaser triggered a computer to activate their backup copies back home. That tidbit confirms that nothing goes faster than the speed of light and explains why no one tried to come up with a plan to not sacrifice a portion of the crew. They resided in the engine compartment and really couldn't be saved.

Since they have first hand experience of something that should be impossible and that knowledge killed a bunch of people, they do their best to hide it from people back on Earth. It's a cross between a murder mystery and accident investigation. It could get even weirder than the first story if these two AI programs start to imply that everyone on the ship was an AI and not a physical person. In this case, the broken trope isn't magical energy gains or FTL travel, but AI's so advanced they are indistinguishable from humans. Including lapses in reason and logic. An AI that can fool itself into not doing math is a pretty strange creation.
Are they uploads? We already know human minds can fool themselves pretty easily.

29. Originally Posted by Noclevername
Are they uploads? We already know human minds can fool themselves pretty easily.
For decades, I have tinkered with the idea of both AI's and uploads. Most of my stories exist within the same fictional universe and both exist. But if they don't have a realistic purpose, the ends aren't going to be that great.

One of my earliest scenarios is humans create a combat AI that is so infused with "human logic" that they won't fight. It's a disaster for the military hawks who want a war but nothing horrible actually comes of it. War is averted. The "infected ships" make themselves available for non-combat purposes, but it's wise to keep them away from any place that has weapons because the AI doesn't think they are necessary or desirable. They can outsmart people to the extent that they can hack systems connected weapons so that they become "safe".

Another technology I have with no explanation is a single human uploaded into a spaceship's computer. This was done by Aliens as a means of first contact. (No one has FTL, so effective immortality is a the only obvious way around slow travel for characters.) It doesn't go well because the humans are working a completely different "upload process". They have a system called a Link, which conveys medical information via a network and doctors can speak to each other in what seems to be real time because each local machine has an AI that can simulate responses of other users. The Link creators mulled over what this would mean for people, and decided it was a non-issue because the technology to make a realistic human like AI wasn't there. Centuries later, that assumption is very wrong.

The Alien tech "upload" is also far from perfect, it's based on a human that didn't want that to happen to him or her and it desperately is battling conflicting needs, some of them emotional. It doesn't want to be alone, it has to follow it's programming which isn't desirable from a human perspective. Ultimately what happens is the Link AI's connects up with the Alien upload and a brief war occurs. Since the Alien Upload is traumatized by being alone and forced in this situation while the human created Link has the primary purpose of healing, the "war" is far from destructive. The Alien upload enters the Human link system and is repaired and cared for. The ship it resided in is disabled. But now all human users of the Link tool are now subjected to Alien thoughts as a result of programming, which don't operate along human logical thought processes. This causes a lot of problems.

After a while, the Link gets so good at simulating users that humans start to think of the simulations as a independent copies of the person. This is problematical.

Since all of the humans are travelling at very low speeds to different star systems, the various groups develop this technology in different ways. One group discovers a way to freeze people for transport, but uses the Link tool to stimulate the passenger's brain so they can survive the process with their intellect intact. They also invent an AI to pilot the ship and care for the passengers. The AI is responsible for creating "Chimeric Space", where the human minds interact and function while frozen. They are temporarily upload, but return to their bodies on arrival. It's sort of like a "super holodeck" where the users don't have the obvious problem of interacting with unreal objects in a real space.. Everything that happens in "Chimeric Space" stays there and the person remembers it as a powerful dream. Nothing "physical" is happening there. It's odd because "Chimeric Space" is the one way that humans can interact with the ship's AI directly. The AI is so complex and strange it can't speak to humans at all. It has representative computer programs and robots that communicate its needs and intentions to humans. They have some features of a simulated AI, but simply but highly sophisticated programmed machines.

I am not entirely convinced that an intelligence residing in a machine, either AI or upload, would be functionally different. They end up with the same limitations and capabilities.

30. The scenario is not much different from two ocean ships limited by their Froude number, in a chase. Then you introduce AI. It is hard to plot space fiction that avoids just another examination of human nature in conflict. But self aware AI can be imagined as very different from human. It’s food and reproduction needs can be gone, or very different. It can evolve to value very different goals. But these have been explored, and Douglas Adams did better than most! Two such AI in conflict could be very different from human conflict but would that be interesting to human readers?

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