Author Topic: If we had FTL travel, would we know where to go?  (Read 3426 times)

Offline NedB

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If we had FTL travel, would we know where to go?
« on: 12/01/2021 11:21 am »
Assume, just for a moment, that FTL was possible. I guess also assume we know how MUCH faster than light we are traveling. Do we have enough data to calculate _where_ an object light years away would be now? If so, how far away could we calculate fairly reliably, so as to not arrive within object?

Offline rakaydos

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Re: If we had FTL travel, would we know where to go?
« Reply #1 on: 12/01/2021 01:18 pm »
You're going to have to define "reliably" for us. Assuming your talking a Star Wars style "jump to hyperspace", ignore everything between you and the destination, with no pre-built infrastructure (wormholes, ect), type of FTL, we could probably reliably put a probe into some kind of orbit around our nearest stars.

Once we have FTL probes, however, all bets are off. Even being able to "stop short", recalculate, and reactivate FTL makes visiting distant galaxies trivial.

Offline spacenut

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Re: If we had FTL travel, would we know where to go?
« Reply #2 on: 12/01/2021 01:23 pm »
I would assume we would travel to stars that have planets in the habitable zones.  We would try to find a planet with water and an atmosphere similar to Earth or Mars with a gravity of 1g or less and not inhabited by intelligent beings, so we could colonize it. 

Online TrevorMonty

Re: If we had FTL travel, would we know where to go?
« Reply #3 on: 12/01/2021 02:32 pm »
Any planet that can support humans without spacesuits is likely to contain life. There is good chance some of  the local  micro organisms will be deadly to us ie  Martians from War of Worlds.
Its a two way streak, we'd endup contaminating planet with our micro organisms.

We maybe better off on a sterile world with atmosphere that doesn't require pressure suit. May still need life support system. Not   having to deal with vacuum makes construction of habitats lot easier.


Sent from my SM-G570Y using Tapatalk
« Last Edit: 12/01/2021 02:33 pm by TrevorMonty »

Offline JayWee

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Re: If we had FTL travel, would we know where to go?
« Reply #4 on: 12/01/2021 02:36 pm »
You're going to have to define "reliably" for us. Assuming your talking a Star Wars style "jump to hyperspace", ignore everything between you and the destination, with no pre-built infrastructure (wormholes, ect), type of FTL, we could probably reliably put a probe into some kind of orbit around our nearest stars.

Once we have FTL probes, however, all bets are off. Even being able to "stop short", recalculate, and reactivate FTL makes visiting distant galaxies trivial.
The big question is whether the FTL "cancels" relative velocities of orbital bodies, or you'd have to do it the old fashioned propulsive way.
Ie, how much delta-v would be necessary to actually orbit a planet in a distant solar system?

Offline webdan

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Re: If we had FTL travel, would we know where to go?
« Reply #5 on: 12/01/2021 03:12 pm »
Read this and come back.

"The Engines of God" is a science fiction novel by American author Jack McDevitt.

https://en.wikipedia.org/wiki/The_Engines_of_God

Great series.

Offline rakaydos

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Re: If we had FTL travel, would we know where to go?
« Reply #6 on: 12/01/2021 06:10 pm »
You're going to have to define "reliably" for us. Assuming your talking a Star Wars style "jump to hyperspace", ignore everything between you and the destination, with no pre-built infrastructure (wormholes, ect), type of FTL, we could probably reliably put a probe into some kind of orbit around our nearest stars.

Once we have FTL probes, however, all bets are off. Even being able to "stop short", recalculate, and reactivate FTL makes visiting distant galaxies trivial.
The big question is whether the FTL "cancels" relative velocities of orbital bodies, or you'd have to do it the old fashioned propulsive way.
Ie, how much delta-v would be necessary to actually orbit a planet in a distant solar system?
With precice enough teleportation/FTL, you can arrive in a capture slingshot trajectory relative to some major body in the system.

Offline RonM

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Re: If we had FTL travel, would we know where to go?
« Reply #7 on: 12/01/2021 06:15 pm »
Assume, just for a moment, that FTL was possible. I guess also assume we know how MUCH faster than light we are traveling. Do we have enough data to calculate _where_ an object light years away would be now? If so, how far away could we calculate fairly reliably, so as to not arrive within object?

Stellar positions and transverse motion on the sky are well known, but accurate distance isn't. Even with the Gaia mission's more accurate data, you'd have to 'jump' to a guessed position and take a look to see how far off you are. Once the first mission successfully arrives the position and vector will be known.

Space is incredible vast compared to the size of stars or planets. So, there's almost no chance of accidently arriving in an object.

Offline Lee Jay

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Re: If we had FTL travel, would we know where to go?
« Reply #8 on: 12/01/2021 06:30 pm »
Assume, just for a moment, that FTL was possible. I guess also assume we know how MUCH faster than light we are traveling. Do we have enough data to calculate _where_ an object light years away would be now? If so, how far away could we calculate fairly reliably, so as to not arrive within object?

Stellar positions and transverse motion on the sky are well known, but accurate distance isn't. Even with the Gaia mission's more accurate data, you'd have to 'jump' to a guessed position and take a look to see how far off you are.

I suppose, but for nearby stars, you should be able to get pretty close:

https://www.esa.int/Science_Exploration/Space_Science/Gaia/Frequently_Asked_Questions_about_Gaia

"The accuracy of the distances obtained by Gaia at the end of the nominal mission will range from 20% for stars near the centre of the Galaxy, some 30,000 light-years away, to a remarkable 0.001% for the stars nearest to our Solar System."

That's 5 light-minutes for each light-year.  Not bad!
« Last Edit: 12/01/2021 06:36 pm by Lee Jay »

Offline RonM

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Re: If we had FTL travel, would we know where to go?
« Reply #9 on: 12/01/2021 06:45 pm »
Assume, just for a moment, that FTL was possible. I guess also assume we know how MUCH faster than light we are traveling. Do we have enough data to calculate _where_ an object light years away would be now? If so, how far away could we calculate fairly reliably, so as to not arrive within object?

Stellar positions and transverse motion on the sky are well known, but accurate distance isn't. Even with the Gaia mission's more accurate data, you'd have to 'jump' to a guessed position and take a look to see how far off you are.

I suppose, but for nearby stars, you should be able to get pretty close:

https://www.esa.int/Science_Exploration/Space_Science/Gaia/Frequently_Asked_Questions_about_Gaia

"The accuracy of the distances obtained by Gaia at the end of the nominal mission will range from 20% for stars near the centre of the Galaxy, some 30,000 light-years away, to a remarkable 0.001% for the stars nearest to our Solar System."

That's still a miss of almost 3 AU to the nearest star. Not bad, but not that great depending on the ship's 'sublight' drive. No problem with an EM drive, but a problem with chemical rockets. Anyway, it's only an issue on the first mission.

Another issue is how good is this fictional FTL? Might have to 'jump' to the outer system and take a bearing before going to your destination.

Online whitelancer64

Re: If we had FTL travel, would we know where to go?
« Reply #10 on: 12/01/2021 07:02 pm »
It would be reasonable to assume that this FTL drive was initially developed in the solar system and cut its teeth going between Mars and Earth, Earth to Jupiter, etc. so a 3 AU jump should be trivial for it to accomplish.
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
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Offline RonM

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Re: If we had FTL travel, would we know where to go?
« Reply #11 on: 12/01/2021 07:15 pm »
It would be reasonable to assume that this FTL drive was initially developed in the solar system and cut its teeth going between Mars and Earth, Earth to Jupiter, etc. so a 3 AU jump should be trivial for it to accomplish.

That's not always the case in science fiction. All depends on the limitations of the FTL system which are not mentioned in the OP.

Offline Bob Woods

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Re: If we had FTL travel, would we know where to go?
« Reply #12 on: 12/01/2021 10:51 pm »

That's still a miss of almost 3 AU to the nearest star. Not bad, but not that great depending on the ship's 'sublight' drive. No problem with an EM drive, but a problem with chemical rockets. Anyway, it's only an issue on the first mission.

Another issue is how good is this fictional FTL? Might have to 'jump' to the outer system and take a bearing before going to your destination.
If we have figured out FTL, I'd guess we probably would have had to figure out "high speed" impulse in advance.

Offline edzieba

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Re: If we had FTL travel, would we know where to go?
« Reply #13 on: 12/02/2021 10:17 am »
Assume, just for a moment, that FTL was possible. I guess also assume we know how MUCH faster than light we are traveling. Do we have enough data to calculate _where_ an object light years away would be now? If so, how far away could we calculate fairly reliably, so as to not arrive within object?
Far too open a question given the vast number and variety of fictional FTL schemes. Depending on what arbitrary restrictions you add to your fictional FTL system for reasons of plot, measurement issues could be trivialised. e.g. making multiple 'jumps' incrementally close to refine your position estimate. Or making jumps of a few light-years to either side of your origin to give you a wide baseline for target triangulation (and a helpful temporal offset for velocity measurement). It's all based around whatever imaginary FTL system you choose/design rather than any physical limitations, because those have already been tossed out the window along with causality.

Offline Turgin

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Re: If we had FTL travel, would we know where to go?
« Reply #14 on: 02/24/2022 08:32 pm »
If one is going faster than light...

Normal cameras will not work at FTL speeds.

the photons literally should not reach them.

All the camera would see is whatever the quantum vacuum of space naturally looks like as seen through a photon collector that is unable to collect said photons at FTL speeds.

Online DanClemmensen

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Re: If we had FTL travel, would we know where to go?
« Reply #15 on: 02/24/2022 11:20 pm »
Assume, just for a moment, that FTL was possible. I guess also assume we know how MUCH faster than light we are traveling. Do we have enough data to calculate _where_ an object light years away would be now? If so, how far away could we calculate fairly reliably, so as to not arrive within object?
That assumption puts you in an alternate universe. You would need to tell us exactly which laws of physics are different before we could answer your question.

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