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this post was submitted on 16 Jan 2024
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Anyway the lazy, boring way to use a portal and pretend you aren't violating a bunch of physical laws is to just use it for fuel transport.
You have a bunch of fuel on the ground, a tiny tank on your rocket, and you keep topping off the rocket's tank by piping in the fuel.
BTW, as a variant on the kzinti lesson, the portals are extremely dangerous as a weapon, because of how good they are as a weapon.
Ignoring the obvious ways to fight with them like opening a portal on the enemy's hull, shoving out a nuke and then closing the portal...
You could also just have a rock that you're letting accelerate to arbitrary speeds in a vacuum. That's free unbounded kinetic energy, the only limitation being the "charge" time.
This isn't a ship-destroying weapon, this is a civilization-ender if not planet-killer.
You've got a projectile moving at a significant fraction of the speed of light. This is a relativistic weapon: it's going to hit harder than if it was a nuke.
You can also make it bigger by not using a roughly round rock and instead using a long rod of the densest material you can get your hand on.
But mass you pay for, speed you don't.
Like, the worked example from Atomic Rockets has 7 kilograms of cat litter moving at 90% of lightspeed hitting a stationary target with 195 megatons of kinetic energy.
https://www.projectrho.com/public_html/rocket/spacegunexotic.php
But yeah this is the ultimate doomsday weapon. You can accelerate indefinitely for free, you just have to wait.
(and if you can put your portals in orbit of a more massive object, you get faster acceleration than 1g)
So you don't need more than a portal gun, a tungsten rod, and some time to blow the atmosphere off a planet.
@[email protected] how do you make sure it's aligned right? It's no good if it drifts to the side and hits the edge of the portal, maybe already at a dangerous speed, at your weapon site rather than your target
Sir Isaac Newton may be the deadliest son of a bitch in space, but the deadliest son of a bitch in the Half Life universe is Cave Johnson.
The Nihilanth could teleport an entire army to earth, the combine can conquer a planet in hours, the g-man has control over time and space, but Cave Johnson's invention could put a hole in a planet
@[email protected] boring "explanation" that the energy which can cross a portal is limited by the power of the portal generator - so you can only accelerate to c if your generator can output that much juice - it's not free just super efficient
Alternate ending to Half Life Alyx where it turns out the scary thing the Combine has locked up in the vault is Chell.
There's also the gravity interaction: an infinitely falling object that never reaches the bigger body is also accelerating the bigger body.
Your forever falling object is shoving the earth upward, very slowly. That could matter in the long enough term... But it seems kinda meaningless compared to the other ways you could use a portal.
Still, might be handy if you need to adjust the orbit of a planet and are willing to wait.
It would be a very Cave Johnson thing to try to fix global warming by pushing the earth away from the sun.
@[email protected] This actually happens in Chicken Invaders 5
https://www.youtube.com/watch?v=AtCrwF0RoO4&t=5965 then they mention staving off climate change in the last cutscene
The only thing more Cave Johnson would be using relativistic weapons to blow up the sun
The lab boys tell me that if you dump enough iron into a star, it'll turn off. Well, we don't have that much iron on hand, but what if it's moving at 99% the speed of light?
They told me that wouldn't help, but I said pack your bags: We're doing it anyway
@[email protected] You just so happened to catch me while I had enough gunk in my throat to have a proper shake at the voice
@[email protected] awesome!
@[email protected] heavy coughing so the experiment went fine, it was quite interesting! the control group told me they'd be experiencing some influence as well, but it's probably just some measuring error. at least that's what the lab boys tell me.
@[email protected] I wonder if the lab boys can find a way to convert energy to matter. If so, then you get an infinite iron machine because a portal is an infinite energy machine. If it go brrrrrr fast enough, Johnson might be able to create enough iron to end the sun.
@[email protected]
In a book (Bobiverse) two moon sized bodies were accelerated to very close to speed of light, and hit a star, coming at it from opposite directions.
Result was described as basically a nova.
@[email protected] probably the best pitch for Portal 3 so far
@[email protected] valve's got my resume, they're welcome to hire me anytime :)
@[email protected] don't forget as well that the portal transit is instantaneous. Never mind the other implications, that alone breaks the universe in a number of exciting ways
@[email protected] @[email protected] Without even seeing your first toot, I read this in Cave Johnson's voice. Bravo, good job.
Portal 2 does establish that the portal-placing shot moves at the speed of light, but that just raises the question of how fast you move through the portals themselves.
It basically can't be slower than light, or you'd chop yourself in half if you moved halfway into one and then backed out.
So it has to be lightspeed: which means, if relativity is still correct, that it's also a time machine.
@[email protected] but how does this relate to Primer?
Maybe not one that lets you trivially violate causality but with moving portals or multiple portals, whoops...
Anyway once you're flying around the universe with your FTL portal-rockets the next question is what happens if the two ends of a portal are moving at different speeds through time. What if you drop one end into a black hole?
And what if you put one end on an enemy planet and the other end in low orbit around Betelgeuse when it finally goes supernova?
How many gamma rays will come through a hole in space about a meter across?
@[email protected]
In @[email protected] 's Glasshouse, they would drop one end of a very small portal into a blue giant star and the other end over to some kind of power plant, and they'd have all the energy and all the power they'd ever need.
@[email protected] the gamma rays are gonna be mostly negligible when you get hit with particulate accelerated with a foe of energy
@[email protected] I was thinking that the portal would be very short-lived, because the surface you placed it on would be quickly destroyed, but there'd be a short period where the initial gamma rays make it through.
but yeah, if you can somehow keep it open longer than milliseconds after the instant of the star's collapse, you'd absolutely wreck anything near the endpoint
my guess based on how big supernovas are (bigger than that. no matter how much you estimate "that" to be), the answer is "enough"
anyway so there's a point in Portal 2 where you fire a portal at a surface that's far enough away that there's noticeable light-speed delay before the portal opens, right?
but is that based on the distance between portals or the distance from the gun?
like, in the game's specific scenario, the distinction is irrelevant, but the portal gun is mobile after all. what if you set up a portal on earth, then hop in a rocket to pluto, then when you land, you fire it at the surface of pluto.
The distance between the gun and the surface is minimal, but the portal pair you just set up is about 5 light-hours long.
Does it take 5 hours for the portal to open? or does it open instantly?
anyway the fact the aperture science facility extended so deep underground in portal 2 was interesting.
hey, you know what a very deep underground facility would be real useful for? dropping stuff through portals and having it fall a long time, accelerating as much as possible.
I bet there's a borehole we never see that's just top to bottom and has as much atmosphere as possible evacuated from it, to lower air resistance
@[email protected] as long as you have two portals set up in a loop, would the actual distance between them matter at all? You could just put two portals 1nm apart in a vacuum and create an infinite accelerator. Then move the exit portal and BOOM
@[email protected] Why even bother evacuating the atmosphere, that's probably how they manage to heat the whole place :-)
@[email protected] Fun fact: holes like this are also useful for testing the effects of microgravity. NASA maintains several near Cleveland for studying the effects of microgravity on fluids like air, water, plasmas, etc. IIRC you get useful results until you hit terminal velocity
@[email protected] My first thought was the Stargate thing where the effects go through the portal, but they didn't have the other in a black hole, just near it.
Would that make the portal one-way? Would it allow things to escape the event horizon? Would a portal even be able to go into one? What makes a surface capable of holding a portal? Would those properties cease in a black hole? Interesting questions.
@[email protected] speaking of relativity, how about the fact that supposedly can't be placed on moving surfaces? Moving according to whose reference point?
@[email protected] i think 1) what travels at the speed of light is the shot from the portal gun to the surface
@[email protected] There's a Cave Jonson voice line that mentions the possibility that testing the ASHPoD may involve "trace amount of time travel".
@[email protected] the portals connect space, you don’t move through them at the speed of light, you move through them at whatever speed you move in the space around them since they’re no different than any other plane cut through it.
@[email protected] Exclusive footage of Cave Johnson after performing the "turn star off" experiment dropped.
@[email protected] "... with the lemons"
@[email protected] One wonders what kinds of electromagnetic interaction tricks you can do with portal technology as well. At the very least, you can build a computer that's physically enormous while being linked together through portals as if it's microscopically adjacent.
@[email protected]
This seems like a combination of https://what-if.xkcd.com/147/ and https://what-if.xkcd.com/12/
@[email protected] Now this is bugging me too. If you actually wanted to loop a falling object between two portals and forget about it, would it have to be at one of the Earth's poles? I feel as though otherwise the object would start to drift out from between the two portals due to the Coriolis effect (ignoring the fact that an object left falling like this at the equator would constantly be cancelling out whatever effect it produced 12 hours previously).
@[email protected]
I think this is predicated on the assumption that a portal acts as if it's anchored the same way a bell is to a rocket engine.
I don't think it is. Does anything in the games show a portal imparting thrust onto the wall/object it's mounted on? I don't think so. I think portals can't be used for thrust.
It's also pretty clear to me that transfer through a portal is instantaneous, not limited to lightspeed. You can hang out/change direction halfway through a portal as much as you want.
@[email protected] So with something 4 times bigger than the Tsar Bomba we could get a bag of cat litter to 90% the speed of light?
@[email protected] That passage out of The Killing Star when the Relativistic projectiles hit Earth...