The Astronomy Thread

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Mudcrush Durtfeet

Mudcrush Durtfeet

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You can most easily get to huge ships if you can manage really cheap access to orbit. Only SpaceX is getting anywhere with that first part any time soon.

We've already done one huge 'ship' (the ISS) so it's not completely impossible.
 
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Kharzette

Kharzette

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They are doable with a few big breakthroughs:

Need electricity based non propellant propulsion. Several are in the works but who knows if they are actually real.
Fusion. 20 more years? 😆
The aforementioned space infrastructure. Need mining / smelting / welding in space.
A way to do cooling. Big ass fins work but you can't arrange them effectively if you plan to move at high speeds. AI should help with this.

Remember that most of the blather thrown about on "infinite energy needed to get near C" stuff is done by people that don't understand relativity. Acceleration costs don't suddenly increase from the onboard frame of reference. If it takes 10 gigawatt to accelerate at 1G it will continue to take 10 gigawatt forever. There's no magical speed barrier.

All of the above just needs some staggeringly rich people to make it happen. Engineers aren't stupid, they work where the money is. Give a good formula 1 team any of the above challenges and an unlimited budget and they will deliver.
 
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Captain Suave

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Kharzette said:
non propellant propulsion. Several are in the works but who knows if they are actually real.
Click to expand...

If it's anything it will be laser thrusters, but that comes with needing major revolutions in the weight required to generate the necessary huge amounts of energy.

Kharzette said:
Remember that most of the blather thrown about on "infinite energy needed to get near C" stuff is done by people that don't understand relativity.
Click to expand...

Erm. Relatively pretty strongly disagrees with you, otherwise c wouldn't be a constant.

Kharzette said:
Acceleration costs don't suddenly increase from the onboard frame of reference. If it takes 10 gigawatt to accelerate at 1G it will continue to take 10 gigawatt forever. There's no magical speed barrier.
Click to expand...
Within the limits of non-speculative technology, you can't actually get constant acceleration from a propulsion source with a fixed impulse (all of them). There are diminishing returns the faster you travel. With rockets as an example, if you keep accelerating eventually you'll reach the point where your propellant out the back ends up a dead stop, after which you can't go any faster no matter how much fuel you have. Plus there's the issue of drag, which goes up with the square of the speed. The force isn't too high in the interstellar medium, even near c, but ship material integrity becomes a problem, and god help any organic life inside because at that speed you've converted the entire universe into ionizing radiation.
 
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Kharzette

Kharzette

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All the energy requirement figures are from the point of view of an outside observer. Shipside there's no magical increase in acceleration cost. Path lengths contract and time dilates but it doesn't really make any difference shipside.

A few miles of ice on the front of a long slender ship is one way to handle dust grains but yea the radiation will be a problem. All the light of the universe gets focused to the front and shifted way blue. Lots of lead? I dunno!

Shawyer has math that shows why his stuff doesn't violate conservation but personally I don't really care how things work as long as it works. That's been 90% of the argument against testing new forms of propulsion... but but but conservation of momentum! Who cares, try it! If it works it works, if it doesn't it doesn't. I think a lot of effort is wasted on theory.

Rockets are worth making awesome because they will probably be the way to orbit even if we do find new forms of propulsion. The reactionless stuff will need huge arrays of them to work well + big heavy reactors, and that means big ships, and I just don't think you can build big stuff that wouldn't just fall apart in a gravity well.
 
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Captain Suave

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Kharzette said:
All the energy requirement figures are from the point of view of an outside observer. Shipside there's no magical increase in acceleration cost. Path lengths contract and time dilates but it doesn't really make any difference shipside.
Click to expand...

The different frames of reference experience very different things, yes, but you'll still never be passing photons. Plus when you stop you're left with an enormous reconciliation between your perceived time and observers at relative rest during your trip, which greatly warps the concept of speed.
 
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Oldbased

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We need gravity well ( and anti gravity functioning like magnets ) generators to solve many issues.
I'm certain it CAN be done but how many thousands of years will it take for us to do it.
Would solve many issues on reentry as well as attraction and deflection of many space particles.
We also need space cats, because meow.
 
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Mudcrush Durtfeet

Mudcrush Durtfeet

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Captain Suave said:
If it's anything it will be laser thrusters, but that comes with needing major revolutions in the weight required to generate the necessary huge amounts of energy.



Erm. Relatively pretty strongly disagrees with you, otherwise c wouldn't be a constant.


Within the limits of non-speculative technology, you can't actually get constant acceleration from a propulsion source with a fixed impulse (all of them). There are diminishing returns the faster you travel. With rockets as an example, if you keep accelerating eventually you'll reach the point where your propellant out the back ends up a dead stop, after which you can't go any faster no matter how much fuel you have. Plus there's the issue of drag, which goes up with the square of the speed. The force isn't too high in the interstellar medium, even near c, but ship material integrity becomes a problem, and god help any organic life inside because at that speed you've converted the entire universe into ionizing radiation.
Click to expand...
This is wrong. You can accelerate forever, it's just as an observer sees you approach the speed of light they see your acceleration seem to diminish. From the rocket's point of view the acceleration still has full effect. 1G of acceleration will make you feel your normal weight.

One of the weird things about velocity is there is no way to measure absolute velocity. It is always measured in reference to a second object. If you are floating alone in a universe, you cannot tell what velocity you have. The question in such a case is actually meaningless.
 
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Captain Suave

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Edit: Derp, disregard.

Different point. I'm saying that a chemical rocket (or anything with a finite impulse) can't accelerate you indefinitely. When your speed reaches the exhaust velocity of your propellant you can't go any faster, and you will approach this speed asymptotically. This has nothing to do with relativity.
 
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Mudcrush Durtfeet

Mudcrush Durtfeet

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Kharzette said:
All the energy requirement figures are from the point of view of an outside observer. Shipside there's no magical increase in acceleration cost. Path lengths contract and time dilates but it doesn't really make any difference shipside.

A few miles of ice on the front of a long slender ship is one way to handle dust grains but yea the radiation will be a problem. All the light of the universe gets focused to the front and shifted way blue. Lots of lead? I dunno!

Shawyer has math that shows why his stuff doesn't violate conservation but personally I don't really care how things work as long as it works. That's been 90% of the argument against testing new forms of propulsion... but but but conservation of momentum! Who cares, try it! If it works it works, if it doesn't it doesn't. I think a lot of effort is wasted on theory.

Rockets are worth making awesome because they will probably be the way to orbit even if we do find new forms of propulsion. The reactionless stuff will need huge arrays of them to work well + big heavy reactors, and that means big ships, and I just don't think you can build big stuff that wouldn't just fall apart in a gravity well.
Click to expand...
There are no 'reactionless' motors that are being developed that will replace rocket engines. If you are talking about ion engines and whatnot, they do operate off a reaction principle and do have a loss of mass as a propellant of sorts.
 
Mudcrush Durtfeet

Mudcrush Durtfeet

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Captain Suave said:
Different point. I'm saying that a chemical rocket (or anything with a finite impulse) can't accelerate you indefinitely. When your speed reaches the exhaust velocity of your propellant you can't go any faster, and you will approach this speed asymptotically. This has nothing to do with relativity.
Click to expand...
No. If you accelerate to 99% of the speed of light, you can still use your engines to accelerate as your velocity relative to yourself is still zero. You will feel the full acceleration of your rocket engine and it will SEEM to you that you are getting full acceleration. From an outside observer, you won't seem to get full acceleration but you'l l always have a measurable acceleration.

Think about it, we are all going 90%+ of the speed of light relative to some distant galaxy RIGHT NOW. Are we unable to use rocket engines because of that?
 
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Captain Suave

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Mudcrush Durtfeet said:
No. If you accelerate to 99% of the speed of light, you can still use your engines to accelerate as your velocity relative to yourself is still zero. You will feel the full acceleration of your rocket engine and it will SEEM to you that you are getting full acceleration. From an outside observer, you won't seem to get full acceleration but you'l l always have a measurable acceleration.

Think about it, we are all going 90%+ of the speed of light relative to some distant galaxy RIGHT NOW. Are we unable to use rocket engines because of that?
Click to expand...
Yeah, you're right. Don't do amateur physics on multiple beers, kids!
 
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Cybsled

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Interstellar travel beyond "nearby" systems is always going to require FTL to be feasible. Baby steps. We still need good propulsion system for travel within the solar system. Even The Expanse with their physically questionable Epstein Drive takes a long ass time to get anywhere.
 
Mudcrush Durtfeet

Mudcrush Durtfeet

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Cybsled said:
Interstellar travel beyond "nearby" systems is always going to require FTL to be feasible. Baby steps. We still need good propulsion system for travel within the solar system. Even The Expanse with their physically questionable Epstein Drive takes a long ass time to get anywhere.
Click to expand...
I counter with that interstellar asteroid we discovered not long ago.

Interstellar travel is possible, but it's slow.

Currently there are no technologies we possess that make it possible to travel to another star in a human lifetime.

We need new physics or some serious technological innovation (ie fusion power at a minimum).
 
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Big Phoenix

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Cybsled said:
Interstellar travel beyond "nearby" systems is always going to require FTL to be feasible. Baby steps. We still need good propulsion system for travel within the solar system. Even The Expanse with their physically questionable Epstein Drive takes a long ass time to get anywhere.
Click to expand...
Nah. We could colonize the entire Galaxy with non ftl engines, it would just take hundred of thousands of years to a few million years.
 
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