The most realistic sci-fi engines are nuclear pulse engines where you ride the shockwaves of thousands of fusion bombs to reach a few percent of the speed of light. Those we could probably build right now if we were willing to spend the money. Replacing the fusion bombs with antimatter bombs would be a nice improvement for the basic design

I think the more "practical" idea is to replace the fission stage of a fusion bomb with antimatter annihilation.

i.e.: https://en.wikipedia.org/wiki/Antimatter-catalyzed_nuclear_p..., although it doesn't really replace the primary, just decreases the required quantity.

Is there a way to slow down using fusion bombs? Even if you manage to bring thousands of fusion bombs with you? Sounds like this is only a sensible approach for sending probes, which will then zip by their target at huge speeds.

you just need to speed up in the opposite direction by flipping around and firing bombs on the other side.

Which means if we get discovered by an alien probe it will look a lot like getting on the wrong end of a nuclear war.

I remember there was a quote from some sci-fi universe that there's "no such thing as an unarmed space ship".

I believe that is the "Kzinti Lesson" from Larry Niven:

"A reaction drive's efficiency as a weapon is in direct proportion to its efficiency as a drive."

https://tvtropes.org/pmwiki/pmwiki.php/Main/WeaponizedExhaus...

If you can get any kind of spaceship up to speeds to reach other stars within reasonable time - you've got an amazing weapon. Just ram into something at full speed. Ok, if you have enough energy to correct course to aim, only.

It’s more than twice(1) as easy to make a rocket-propelled bullet than a rocket-propelled vehicle!

1) It’d be exactly twice as easy but for Tsiolkovsky!

Thanks for explanation!

How do you do that and not die?

Long stick and radiation shield between you and the bombs

Isn't it the path to a yet deadlier bomb ? #alwaysLookOnTheBrightSideOfLife

In all (realistic) interplanetary space travel - not to mention interstellar - the difference between the largest bomb/death ray anyone has ever experienced and a better drive, is purely a matter of where you aim it and when/how you throttle it up.

The most hilarious part of the expanse for instance is how they didn’t really use their actual drives as weapons even in CQB, which is quite a waste!

Not actually that different for rockets now, frankly, we just usually don’t operate direct nuclear fission/fusion drives right now for this very reason and our own sense of self preservation.

There certainly are plans on the drawing board!

It would take 23 grams of antimatter to produce the effect of a 1 megaton nuclear bomb, and the biggest factor stopping someone is both production of the matter itself (improving) and actual shielding technology (magnetic bottles good enough to effectively trap that much antimatter are huge and extremely energy consuming right now - much bigger than a fusion bomb of equivalent power).

Theoretically, it should be possible to store that much in a thermos bottle, however. We just need better superconductor technology.

Just be-fore you draw your terminal breath ♫

No. Unless you find a chunk of antimatter or a way to break the laws of physics.

it brings us 1 order of magnitude closer

10 more to go!