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Weird physics thread
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Weird physics thread
Weird physics thread
This is a thread to talk about certain physics stuff that is confusing and weird.
Like the phenomenon associated with the twin paradox. In the twin paradox, one twin goes on a journey to somewhere in space and returns, and when he returns, he is younger than the other twin. This relativity-related phenomenon can be explained by that if someone is taking off in a plane and someone else is on the ground, if they point their flashlights to the same spot, they will agree on the speed of the light they are releasing (186,000 mi/s or 300,000 km/s), but they will disagree on the distance. Since distance/time = velocity (of an object), they will also disagree on the time. The equation for this is:
t = t.o / √1 - v^2 / c^2
where t is the time passed for the unmoving subject, t.o is the time passed for the moving subject, v is the velocity of the moving object, and c is the speed of light (186,000 mi/s or 300,000 km/s). The equation can also be altered like so:
t = t.o / √1 - p
with the same variable values except for p, which is the proportion of the velocity to the speed of light (traveling half the speed of light would make p 0.5, for example).
Back to the twin paradox:
If the traveling twin is traveling at one-quarter of the speed of light for 6 years to the destination, stays there for 1 year, and returns traveling at half the speed of light for 3 years, we can plug his travel time into the equation. That means that at home, about 6.9 years have passed (during his way to the destination), the time is the same for his stay, and on his way back, approximately 4.2 years have passed. 6.9 + 1 + 4.2 = 12.1, so 12.1 years have passed for his other twin, and his twin is 12.1 years older (or 12 years, 36 days, and 12 hours). But the traveling twin is only 10 years older. Crazy, right?
Also the only reason light is able to travel at the speed of light is because it is made of photons (a combination of a particle and a ray), which have no mass.
Sorry for this long post @admins.
submitted by Golden Lion Tamarin, age 8, California, he/him
(January 18, 2022 - 7:43 pm)
(January 18, 2022 - 7:43 pm)
Superconductors are pretty funky, they're materials that conduct electricity with essentially zero resistance. One of the classic demonstrations with them is quantum levitation, where a magnet can be levitated over a superconductor or vice versa.
The way that works is, uh, so a magnetic field in motion induces an electric current in conductors, ya? That's how a generator works, a magnet is rotated or oscillated inside a coil of wire, inducing a flow or alternating current in the wire. But just as a moving magnetic field induces currents, a current creates a magnetic field. So one weird thing that can be done is if, say, a magnet is dropped over a conductive and non-magnetic material, it'll induce currents in the material, and the currents will generate a magnetic field opposing the falling magnet's— making it fall slower.
Superconductors are special tho. Since they have no resistance, the opposing magnetic field they generate will be of equal strength to the falling magnet— enough to keep it from falling entirely.
Now, if the superconductor in this situation was perfect, the magnet would just be pushed off to the side, like when you drop a magnet over an opposing magnet. But if the superconductor is just very good but not quite perfect, and still has spots that aren't superconducting, the magnetic field will penetrate those parts and do something called flux pinning, where the field lines that can go through the superconductor keep the magnet in the position it's placed relative to the superconductor (or vice versa).
Superconductors would be incredibly useful for maximizing efficiency in power generation and transfer but sadly the only superconductors we have now work at at very very cold temperatures. YBCO, yttrium barium copper oxid, is a common "high temperature" superconductor— high temperature because it "only" needs to be at -292°F (-144°C) to superconduct, lol.
(i had fun writing this :0 maybe if i remember i'll be back to talk about superfluids or the black hole information paradox or ion thrusters)
(January 21, 2022 - 1:10 am)
(January 21, 2022 - 1:12 am)
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More weird phenomena!
Until observed, an object can be in multiple opposing states at once by the law of superposition. Like, have you heard of Schrödinger's Cat? If the poison bottle opens, the cat's dead but if it doesn't open the cat's alive, so until observed the cat is both alive and dead. The amplitude, or how much that object is "in" a certain state is equal to the square root of the probability of that state. So for schrodinger's cat, the cat is 1/√2 (or, to have a more civilized fraction, √2/2) dead and 1/√2 alive, which is COMPLETELY CRAZY!
Speaking of strange physics, what is the algorithm of tops? I think it might arrange the threads by the most popular and the most recent comments. Like maybe it kind of rates each thread by those two factors (with the time since last post being negative) and puts the highest-rated ones at the top? But what about saying "top"? Does that even work or is it just a coincedince that it makes the thread to to the top every single time?
(July 10, 2022 - 12:49 pm)