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0
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3answers
192 views

On boiling, does 1 kg of water give rise to 1 kg of steam?

I understand that by conservation of mass, it implies that 1 kg of water will give rise to 1 kg of steam. But when I consider the fact that there is phase change which is an abrupt and discontinuous ...
1
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0answers
10 views

Having trouble reconciling Newtonian-derived earth mass with direct calculation [closed]

Our calculation of Earth's mass as $M_E=5.97\times 10^{24} \:\mathrm{kg}$ is made by observing the gravitational interaction between the moon and the earth and then solving the relation ...
2
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0answers
47 views

Does a conducting wire give off measurable radiation?

In the Drude model (semiclassical, but should still apply here I think), the conducting electrons are in a constant electric field, and, in between collisions with the lattice ions (that happen, on ...
28
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6answers
2k views

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 ...
3
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0answers
46 views

How would water drain out of a sealed pipe?

While hiking through the Grand Canyon, I started wondering. Say we have a pipe for the purpose of transporting water across a canyon, with the bottom submerged in a pool of water. Like the blue line ...
1
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2answers
39 views

Special Relativity Question: Doppler shift

Imagine an observer watching a moving rocket carrying on it both, a light source and a clock. If on the rocket the clock is synchronized with the frequency of the light being emitted then will not a ...
3
votes
1answer
81 views

Thought experiment: Tethered galaxies - to the extreme

If two rocks were tied together with a tight, absurdly long, non-elastic rope, and placed on planets at either end of Earth's observable universe - or beyond - What would happen? Is the structural ...
0
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1answer
38 views

Trapping an electron

Imagine that one could theoretically trap a single electron in a small box, with walls that somehow prevent the electron from passing through and out of the box. Now, the box begins to move in on ...
0
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1answer
59 views

The mass of the photon will decrease with reduced velocity?

Since photon has zero rest mass, it will has zero mass when the velocity is zero. We are now being able to slower down the photon in experiment. Is the mass of photon reduced with the decreased ...
2
votes
3answers
192 views

How fast can fire spread?

You can build a home-made flamethrower by using a spray and a lighter: (from this YouTube video) But this can be dangerous if the fire gets in the can and the can explodes. So I guess the speed at ...
1
vote
1answer
64 views

Bug riding on a ball moving at almost the speed of light [closed]

A ball with a bug on it is thrown at almost the speed of light. The bug looks back and observes the thrower throwing the ball. In the context of special relativity, what is the weight and the height ...
0
votes
1answer
40 views

Is Red-Shift experiment correct?

I been reading: http://www.mth.uct.ac.za/omei/gr/chap5/node2.html. The website seems credible with its contact details & location being extremely accurate and easily verified, and its mathematics ...
18
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3answers
2k views

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 ...
5
votes
5answers
436 views

Uncertainty principle with two photons

Imagine an experimental setup in which you have to measure the momentum and location of a particle. To measure it we know we will have to affect it, and the uncertainty principle would come into the ...
6
votes
2answers
111 views

Flying eggshells

This question was asked on Judaism.StackExchange a few days ago, but I think it has a better chance of being answered here. Disregarding the grammatical discussion in the comments on that ...
53
votes
8answers
7k views

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 ...
12
votes
1answer
548 views

Can a difference in the “speed of time” introduce acceleration? [closed]

Hypothetically, lets say we have a space divided equally into two adjacent areas where (somehow) in one of the areas time goes by at half the speed as the other area. Or specifically, when a clock in ...
2
votes
0answers
74 views

-Thought Experiment- At superluminal speeds, to what degree would vision be impaired? [closed]

I was thinking about superluminal travel when thinking about advanced civilisations in the future. I was also thinking about the Doppler effect; so I decided to think about how light may be affected ...
2
votes
0answers
56 views

The speed of light during the inflationary period

Introduction: As a thought experiment, suppose I modified the value of $c$ (speed of light) in some local region and attempted to measure it with a clock placed in that same region. I will denote ...
4
votes
3answers
450 views

Slowing of time under gravity

I am not calling this gravitational time dilation because that is a relativistic effect due to the equivalence principle. Now imagine two light clocks (a clock that ticks due to light) are placed ...
0
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3answers
99 views

Could this suggest that there is a wavelength smaller than Planck's?

Suppose the earth receives a photon with a wavelength $\gamma_1$. Since spacetime is expanding, we know that this photon had an original wavelength $\gamma_2$, such that $\gamma_2\lt\gamma_1$. This is ...
0
votes
6answers
202 views

Could this mean that Schrodinger's Cat thought experiment is false?

Since it is uncertain on whether or not the cat could be dead or alive, it is concluded that it depends on the observer to make it either dead or alive. But lets look at a clock. It doesn't take ...
5
votes
1answer
60 views

Question on luminosity of a radiant source and its dependence on temperature, and involvement of Doppler Effect

A few days ago, I happened to go through the chapters on Radiation, and Photometry, studying them at quite an elementary level. I studied Wien's displacement law, and the dependence of luminous flux ...
0
votes
1answer
91 views

Why is speed/position relative but acceleration not? [duplicate]

I think i understand it now, if found this: link I know that position and speed are relative. There is no such thing as universal coordinates. Then why is acceleration absolute? Is the 3th and 4th ...
3
votes
1answer
96 views

Put yourself in the shoes of Wolfgang Pauli (1930): How could Pauli have narrowed the culprit down to one particle, instead of many?

A while ago, during my introductory physics course, my professor purposefully neglected to tell us about the existence of the anti-electron neutrino in beta decay; he made it an assignment(on our ...
1
vote
3answers
56 views

What would we observe from thompson's lamp thought experiment?

The thought experiment goes like this: Say there is some circuit which turns a lamp on/off with just a flick of a switch. Say its off; you flick it, it turns on; flick it again it turns off, ...
2
votes
2answers
98 views

Apparent velocity of an approaching object

What would be the apparent velocity of an object approaching us at an actual velocity of $v$? I know $cv/c-v$ is a possible answer but here's another argument - shouldn't the velocity be the Doppler ...
1
vote
1answer
306 views

The scissor paradox: can we pass the information faster than light? [duplicate]

click to view the image Before I start, I want to say that this is not a duplicate of "Is it possible for information to be transmitted faster than light by using a rigid pole?", Since point A is ...
0
votes
0answers
59 views

Time relativity - 'philosophical' question

I'm aware that time is relative to the observer. But, does this also extend to the perception of time? For example, let's consider a fly (there's research suggesting that flies perceive time passing ...
4
votes
3answers
314 views

Thought experiment using quantum entanglement in position and its effects

Consider we have two atoms $a$ and $b$. They are entangled with each other in position and momentum, with some wavefuction describing them in position space that is $\Psi(x_a, x_b)$. This ...
-2
votes
2answers
149 views

If a planet were cut in half but stayed hemispherical, how hot would the ocean on the flat side be? [closed]

Some time ago I asked a question about gravity on a hemispherical planet. What would gravity be like on a hemispherical planet? Would the water all boil away at first, quickly cooling the core of ...
0
votes
1answer
100 views

Is there there is another universe which is made up of antimatter, in large amounts like ours is made up of matter?

Can it be possible that in the big bang, not one, but two universes were formed, one formed of matter, and the other formed of antimatter? It seems logical to me that since our universe is formed of ...
3
votes
0answers
84 views

Why are some things attracted to you but others repelled by you in rotating reference frames?

Note that my understanding of general-relativity is rudimentary. If I understand right, it means that basically any reference frame can be considered stationary, but there may be random gravitational ...
3
votes
1answer
127 views

A problem with a basic thought experiment in Special Relativity

This is for a class on special relativity I am to give to some school children. Moe is moving at 0.9c. At the instant he passed Joe he emits a flash of light. One microsecond later, Joe(at rest) ...
0
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0answers
82 views

Philosophical take on Schrodinger's cat paradox

I'm a mathematics undergrad currently doing a module on quantum mechanics. I am interested to delve into the more philosophical aspect of the paradox. Could anyone please give me some introductory ...
11
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4answers
1k views

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 ...
1
vote
3answers
210 views

Does the velocity of a light source influence the light

I have only just finished High school physics so my understanding is still fairly simple but I'm having trouble with this question. Imagine you are in space traveling at a relativistic speed with a ...
4
votes
1answer
94 views

What happens when the frequency of A.C becomes infinite?

In an alternating current, the flow of electric charge periodically reverses direction, and the number of times it does that is called the frequency of the current. However, if the frequency of an AC ...
3
votes
1answer
124 views

Perpetual motion in spaces of different gravity?

Imagine two locations with different amounts of gravity. I carry up a weight in low gravity, move it on this height over to the other place, and let it fall down there with higher gravity. Wouldn't ...
5
votes
3answers
265 views

Did people realize that gravity accelerated things before Einstein's elevator thought experiment?

I'm reading about the (very near) equivalence of gravitational mass and inertial mass in my undergrad GR course, and the text (Lambourne) describes this equivalence as the inspiration for Einstein's ...
8
votes
7answers
669 views

Is it possible for a sound to be louder as you move away from it?

I was asked a puzzling question/thought experiment: Given the source of a sound in a wide open field so acoustics do not play a role, is it possible for a sound to be louder as you move away from it. ...
1
vote
0answers
129 views

Non-zero charge density due to Lorentz contraction in current carrying wires

In trying to answer this question I came across the following problem. The original question relates to the idea that what looks like a magnetic field in one reference frame, ends up as an ...
3
votes
0answers
1k views

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 ...
0
votes
1answer
136 views

Light behaves as a particle or wave in this thought experiment?

Consider a metal plate, on which a light of appropriate wavelength is incident such that it creates an interference pattern. The wavelength is chosen such that it can cause detectable photo-electric ...