Portal [Interesting Physics]

[Reincarnate]

I hope Portal 3 starts to include some serious relativity puzzles. It'd make for some really, really interesting mindbenders.

[qqwref]

Originally Posted by Reincarnate

According to qqwref, I should be able to tug on the panel and float -- or perhaps keep a constant tug and float up indefinitely. But this doesn't make much sense.

Doesn't make much sense because it's counterintuitive? Or because you see something wrong with the force argument?

Originally Posted by Reincarnate

Trying to pull the panel up will also pull the table + rest of the world up

How so? If the portal panel isn't connected to the table (and I'm assuming it isn't because if that was the intent leonid would've just put the top portal on the table), there's no reason lifting the panel would have any effect on the table.

Originally Posted by Reincarnate

however much you pull up, that much volume will be displaced below the lower portal -- otherwise nothing can be pulled.

What do you mean by volume displaced below the lower portal?

[Izzy]

This might be relevant or irrelevant, but has there been any evidence of changes in time due to extreme velocity? Like if you put a watch in the large hadron collider and had the same watch as a control, would the two watches be any different at all?

I know it's probably taboo to not believe in this concept, but I just find it really hard to believe and as far as I know there has been no evidence to support that the concept of time is a manipulatable dimension.

[fido123]

Originally Posted by Izzy

This might be relevant or irrelevant, but has there been any evidence of changes in time due to extreme velocity? Like if you put a watch in the large hadron collider and had the same watch as a control, would the two watches be any different at all?

I know it's probably taboo to not believe in this concept, but I just find it really hard to believe and as far as I know there has been no evidence to support that the concept of time is a manipulatable dimension.

I feel the exact same way. I remember Bill Nye the Science Guy explaining it to me when I was just a little kid and since then I've always wondered if maybe science has it wrong. Space and Time is beyond me, I have assumptions but I don't think much of them considering they're probably wrong.

[darkshark]

There absolutely is evidence of this. Hell even the satellites that orbit earth have to be programmed to compensate for slight time dilation to stay accurate, and those are only going 10,000-20,000mph

I'm probably rusty on my relativity theory, but the closer you are to achieving the speed of light, the slower time gets. Upon reaching the speed of light (which technically shouldn't even be possible) then time would essentially stop, but only would appear to stop if observed by someone else who was stationary/going the opposite direction. The person who was actually going the speed of light would feel as though time were perfectly normal.

So according to the observer, the watches would get horribly offsync, also works vice versa, the person traveling at lightspeed would see the stationary person's watch as being stopped.

This essentially even gives us the ability to travel hundreds or thousands of lightyears away in a single lifetime given we're able to get close enough to the speed of light.

[Izzy]

But what if that effect has nothing to do with what we think of as time. What if that happens just because of something like your speed is getting closer and closer to the speed at which the electrons are orbiting the atoms. So once both are going at the speed of light there would be no rate of change and thus things would appear to stop. Although maybe this is what "time" is.

[Reincarnate]

All you need to know is that the speed of light is constant for all observers in all reference frames -- and from there you deduce all sorts of wacky phenomena that have been experimentally verified.

[darkshark]

I used to think that time was just something we humans pretty much made up to gauge periods between movements, but the more and more you learn about the physics of time, the less you think it's "made up".

Go look up time dilation on wikipedia or something, really interesting stuff, that will undoubtedly lead to much more in-depth reading material.

[Reincarnate]

http://en.wikipedia.org/wiki/Tests_o...ral_relativity
http://en.wikipedia.org/wiki/Status_...ial_relativity
http://en.wikipedia.org/wiki/Time_dilation
http://en.wikipedia.org/wiki/Relativity_of_simultaneity
http://en.wikipedia.org/wiki/Lorenz_transformation

All worth reading

[Reincarnate]

I just thought of something curious.

In the game, when we put portals on the ground, things bob back and forth, which means that it still feels gravity through the portal even though it's "facing" the ceiling in both cases.

[darkshark]

If one were to very slowly position themselves to the midway point through both portals on the ground, do you float?

[Reincarnate]

In the game, you bob back and forth forever

[darkshark]

Worlds shortest particle (or hell pretty much any object) accelerator.



Red = Magnets

Or remove blue portal once the object is up to speed to create a ridiculously powerful railgun of sorts.

[_Stepdude_]

Originally Posted by Reincarnate

In the game, you bob back and forth forever

I guess it's because the momentum you have when you enter the portal never ends. If you put anything through the portal with x speed, it will exit with x speed and then fall back through the portal with the same speed as before. Even if gravity pulls it down through one portal, the exact same thing happens with the other portal, so they cancel eachother out. Creating the only variable to be the momentum.


I'm sorry, I'm really tired so I hope I made any sense >_>



EDIT


Though if an object were to be placed smack in the middle of 2 portals on the ground, I don't see why the object wouldn't stop.

[qqwref]

Originally Posted by darkshark

If one were to very slowly position themselves to the midway point through both portals on the ground, do you float?

I imagine you would. If you just put something in one of these portals, it would oscillate back and forth, but eventually air friction should bring it to an effective stop.

It's a bit hard to imagine a gravitational field that completely switches directions on a line, but it's probably easier to imagine an electric field with the same behavior (at least thinking theoretically). A point charge in that field would show the same behavior.

[Van T]

Say two spaceships fly off in opposite directions at speeds greater than .5c
The net speed between the two would be greater than c, so would each observe the other as going backwards in time?
e: For the sake of ease of communication/mingling, there are portals linking the two ships

[Ickalanda]

Originally Posted by ninjaKIWI

This is retarded. You're talking about portals, why limit them to the properties of the video game? Clearly if portals could exist, they would be able to be different sizes.

How is this retarded? If a portal is opened connecting two places in space, both the entrance and exit must be the same size unless they are modifying the spacing of the particles entering them, and either way this prevents the table deal from working.

Originally Posted by Gundam-Dude

As can be seen in the posted image, the table traveling through the portal will quickly be halted because the size of the table is determined by the portal on it (I am assuming the portal can not go beyond the edges of the table.

This means that the physical limitations of the table quickly halts any sort of exponential growth you might expect to occur from this situation, as I said in my original post. The table will collide with the other table (or itself o_0) much too quickly into the process, halting movement.

The only way to get this to work is to mess around with the sizing of the portals, making it make even less physical sense than the portals already do haha.

[~kitty~]

Wouldn't sound be able to travel through the portal?

EDIT: I would imagine portals being very very dangerous in real life. What would happen if a portal disappeared while you were going through it?

[leonid]

you will be cut in half

[qqwref]

Related: http://www.webcomicsnation.com/thors...&chapter=26170
(That frog thing is a living portal.)