Hypothetical situation in which, for simplification, only some physical aspects are considered in order to further understand or reveal contradictions between the laws governing them.
Questions tagged [thought-experiment]
409 questions
59
votes
8 answers
Will a blanket warm you if you are underwater?
Suppose a man falls into very cold water and gets their foot stuck under a heavy rock. Fortunately, his head is above water and someone is able to call for help. The paramedics want to keep him warm while they work on freeing his foot. They put a…
Moby Disk
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51
votes
10 answers
Why is the photon clock equivalent to all clocks?
I can understand why, if the speed of light is invariant, a photon clock would tick slower. I find this explanation very useful in terms of introducing the idea of time dilation (also because it allows for the Lorentz formula to be derived…
Swike
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31
votes
6 answers
How to determine your position underground?
Crossed my mind after random rant on wikipedia that lead me to articles about chronometers and measuring position.
Let's assume I were trapped in the underground laboratory with lots of equipment but without any access to the surface. Would I be…
Luntri
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29
votes
5 answers
Is a "hot cube" (analogous to an ice cube) a physical possibility?
Is it possible to fabricate a uranium or plutonium "hot cube" that could be used to keep a cup of coffee hot? Basically a piece of fissile material, shielded, and covered with a non-toxic material that could be dropped into a cup of coffee. Could…
Mark Harrison
- 403
24
votes
6 answers
Black Body Golf Balls
The surface of a golf ball has about 35% more surface area (than a similar sphere) due to its dimples. So my question is simple, given identical radius, ideal black body material, and temperature:
Would this increased surface area allow a black body…
Samuel
- 986
23
votes
10 answers
Ambiguity in applying Newton's shell theorem in an infinite homogeneous universe
Newton's shell theorem has two corollaries:
The gravitational attraction of a spherically symmetric body acts as if all its mass were concentrated at the center, and
The gravitational acceleration inside the cavity of a spherically symmetric body…
pela
- 10,767
21
votes
4 answers
Maxwell's Demon: Why does the entropy of the overall system decrease?
I'm trying to understand the logic behind this famous thought experiment, my confusion is as follows:
In the box on the right after the demon has finished his 'work', I understand that side A now has low entropy since the demon has only permitted…
BLAZE
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votes
3 answers
Would computers accelerated to high speeds compute "faster" from our point of view?
I woke up to this thought yesterday:
Lets say Computers A and B have exactly the same specifications and at time T both are set to process an algorith that would normally take exactly 1 year and exactly at T the A computer is accelerated to 0.5c (or…
Jon
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19
votes
4 answers
Schrödinger's cat; why was it necessary?
Could someone please explain to me the idea that Schrödinger was trying to illustrate by the cat in his box? I understand that he was trying to introduce the notion of the cat being both alive and dead at the same time. But why was it necessary to…
Sarah Jayne
- 625
16
votes
5 answers
Ground → ship Wi-Fi bandwidth in my fast moving spaceship
I have a hypothetical question that hopefully makes sense considering only the rudimentary amount of knowledge I have on relativity.
Assume I am in a spaceship orbiting around a spherical satellite, at a certain fixed radius. The satellite sends…
Maan
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16
votes
3 answers
Why does the 'sticky bead argument' for (gravitational waves carrying energy) work?
Throughout much of the 20th century there was debate about whether Gravitational Waves were real, and whether or not they carrier energy and could be detected. It is often presented that Feynman's 'sticky bead argument' was the strongest…
DilithiumMatrix
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15
votes
4 answers
Can you "rewind" sound messages by going supersonic?
I was having a discussion with a friend about supersonic flights.
It was then when he proposed an idea on an interesting experiment that can be done during a supersonic flight.
The experiment goes like this.
You board a supersonic jet along with…
AlphaLife
- 13,439
15
votes
9 answers
Can you find the length of a pencil without a ruler or clock?
Edit: Assume you do have access to all sorts of instruments, but they are all shrunk in proportion. My real question is:
If you are shrunken (or expanded) by a constant factor and put in a room shrunken by that constant factor, can you be fooled…
ithisa
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14
votes
6 answers
Gravity - What happens when two objects of unequal masses fall freely towards the ground? (Revisited)
The common perception regarding what happens when two objects of equal sizes but unequal mass are allowed to fall freely towards the ground is that - both the objects make contact with the ground at the same instant.
This is attributed to the fact…
Ravindra HV
- 463
14
votes
6 answers
Distinguishing identical particles
I've been going through Shankar's Principles of Quantum Mechanics. In the section of the system of identical particles, he uses an example of billiards to illustrate the difference between identical particles in classical vs. quantum mechanics.
He…
Asy
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