What are some popular sci-fi gadgets that are actually possible to construct in theory?
I am talking about gadgets we see in science fiction movies that obey the laws of physics of our universe and could theoretically be constructed, barring the limitations of materials, energy and time faced by our civilization at the moment.
The nuclear pulse propulsion ship from the novel Footfall.
The technology to produce a spaceship powered by exploding nuclear bombs is fairly basic. It needs to be heavy, and it needs to have massive springs to damper the shock, and thats about it.
A Dyson swarm is basically just a huge number solar collectors orbiting the sun. Humanity could put some individual collectors in space if we wanted to, but we don’t have anywhere near enough resources to make a full swarm.
Near-relativistic spacecraft are conceivably possible and are not too far beyond what’s possible with current technology (though would still require significant advancements). The catch is that they would be very tiny and we would have to send a stream of them to their destination.
Retinal projectors are currently under development, and advanced ones could in principle be higher quality than current VR headsets while having a very small form-factor. Optical metamaterials such as metalenses would be very useful for this, particularly if they could be designed to work at all three RGB wavelengths simultaneously (not easy).
Generation ships. In practice they are outside our capabilities at the moment, but it’s mostly existing engineering … if you could scale up to that, and keep it functional long enough, and keep people healthy long enough, and plan for all eventualities
One that’s on the fringe of what you’re asking is warp drives. Right now it looks like you need ridiculous amount of energy and matter that may or may not exist… But General Relativity is okay with it on principle at least
Not really. It would require negative mass which as far as we know does not exist. And it would generate so much radiation in front of the warp bubble that it would decimate anything nearby when you stopped. There are tons of other major issues with it but those are just 2 I remember off the top of my head.
Of course, if there weren’t any problems people would already be trying to build that shit.
Negative gravitational mass is still a theoretical possibility: nothing’s ever proven Einstein’s equivalence principle. It could be broken for antimatter for example, which could even conveniently explain why there’s so little of it (I remember reading that this hypothesis was investigated not long ago but we can’t produce and conserve enough antimatter to reliably test that mg=mi)
The second problem isn’t an issue if you use it in the vacuum and start and end your trip with classical propulsion.
In fact, the hardest hurdle I’d read on that subject was that with the most efficient warp metrics currently known, you’d still need something like 10^60J for a small spaceship or something ridiculous like that… Orders of magnitude more energy than the mass of the whole solar system.
Which is why I said it was kind of a fringe answer. The fact that physics don’t just flat out say “no” is already kind of amazing, which isn’t to say that it’s definitely possible.
Putting aside the issue that it requires a negative energy density, there’s still the issue that it will necessarily violate causality, which is the reason FTL travel is considered problematic in the first place. Maybe it’s ultimately okay, but it may also mean that warp drives are fundamentally impossible.
Space elevators on a inhabited world seem like a terrible idea though. One terrorist attack and you have a giant rope that will wrap around the world twice, through lots of heavily populated areas. I can see one going from the moon towards the earth though.
I mean like you could do 10x the damage by just redirecting an asteroid or even just gunning it with a fairly aerodynamic ship, its fantasy
But also the ideal elavator would have to be lightweight anyways so eith gravity it wouldnt work against itself, and therefore pretty easily able to burn up in the atmosphere (maximized surface area with the small size).
Also they wouldn’t have to be that long, a stable orbit isn’t super high up there - more like 100km or so.
And then again all this was about desolate planets in the first place
Space elevators need to have the majority of their mass higher than geostationary orbit to hold it up, which is 22000 miles above the earth. So I suppose it wouldn’t wrap around the planet more than once. And while true you can do more damage with an asteroid, it would be a far easier target for a terrorist group than something that far away.
Few decades ago Marvin the Paranoid Android (The Hitchhiker's Guide to the Galaxy) has already been constructed by my human-like parents and is reporting this utmost depressive fact here.
Depends on how far you want to stretch the “barring the limitations of materials and energy” bit, but there are several working theories of gravity drives and things similar to ‘warp drive’ out there. They just have massive energy consumption requirements it would require materials so dense that they approach carrying around a black hole with you. And they would go very, very fast, but not actually faster than light.
In the original story, NASA finds a glowing diamond-like structure on the Moon. For various reasons, Kubrick decided to go with something else. They edited the storyboards and put a black rectangle over the diamond. The rectangle was a symbolic TBA. One day they were looking at the boards and realized that the monolith would actually look very cool.
Years later, after thousands of speculations, a fan approaches Arthur C. Clarke and tells Clarke he’s unravelled the mystery. The ratio of the rectangle is 1 : 4 : 9; those are the squares of the first three numbers. Clarke liked it so much he used it himself.
Dick Tracy’s communicator watch actually seems pretty shitty by today’s standards. His didn’t have a high def LCD screen in it.
Star Trek’s PADD also seems obsolete by real world standards. Those were just e-readers. A tablet is an entire computer, and a smartphone is an even smaller, pocket size computer. There are even phones and devices that connect to phones that do tricorder like scanning of vital signs, the atmosphere, even analyzing the elements that make up an object through spectrographic analysis. Meaning we have the ability to combine the ship computer, a PADD and a tricorder into one device.
Well, the Tricorder had very advanced scanning capabilities. We can’t diagnose and cure cancer with a handheld device yet, but I did get some viral and bacterial tests done in a manner of moments by some desktop lab equipment the other week, so we’re definitely getting there.
One of my favorite scenes is where Seven is handing Naomi a stack of PADDs: “Read this one, then this one, then all these…” Naomi internal: “Bitch, this coulda been an email…”
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