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-1
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2answers
41 views

Relativity asymmetry?

If you have two bodies that move towards each other at a constant velocity, each body will observe the other body experience time faster. This does not make sense to me because if you had a person ...
0
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0answers
37 views

How is a particle observed in the double slit experiment?

I'm having some trouble understanding what is causing so much confusion what this experiment is concerned. As I understand it it is thought that the wave interferes with itself when it's observed, ...
0
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1answer
128 views

Are the authors saying that the observer effect plays no role in Bohr's thought experiment of the Heisenberg uncertainty principle?

Here is an excerpt from Eisberg & Resnick's Quantum Physics of Atoms, Molecules, Solids, Nuclei, and Particles. Here is introducing Bohr's though experiment to establish a physical origin for the ...
0
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2answers
122 views

Speed of light constant for all observers [duplicate]

General relativity has been proven many times over to be correct. In my meager understanding of things, they are all premised on the fact that the speed of light is constant to all observers. I would ...
2
votes
4answers
378 views

What is the universal speed limit relative to? [duplicate]

If all speeds are relative, then what "governing" force is that speed limit relative to? Is there some sort of fixed or absolute grid with locations everything is compared to? Does this also mean ...
5
votes
3answers
1k views

Is it possible to stop time? [duplicate]

Assuming the spacetime principle, if the space is modified the time does too. So if the velocity in the space is increase, does the time slow down? What happens if the speed is the speed of light, ...
1
vote
1answer
53 views

Special relativity: can the velocity of a free object be discontinuous relative to an accelerated observer who stops accelerating?

Suppose an observer ${\it {\mathcal O}}$ leaves point O*, origin of the Minkowski frame K*, in the $O^{*}x^{*} $ direction, with a uniform acceleration $a_{0} $ (as measured by himself) ...
3
votes
2answers
191 views

What is the essence of the Unruh-effect?

The essence of the Unruh effect is basically that coordinate-transformations lead to different excitations/occupation numbers of the quantum fields. Is that statement correct? So in QFT, while an ...
0
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0answers
36 views

Laws of physics for a point in cyclical 2D motion

A follow up question to the question in What does the statement "the laws of physics are invariant" mean? and Formal definition of an observer? Which laws of physics are they talking about ...
0
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0answers
21 views

So far, what has been proven about the definition of an observer? [duplicate]

I've seen people reason that nearly any particle could be an observer, causing electrons in the double-slit experiment to have definite locations. The idea of what exactly the universe/quantum physics ...
-2
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1answer
64 views

Can photons “stop time”?

If traveling past the speed of light causes time to reverse than does traveling in time make time "stop"? If not then how do photons/mass-less particles experience time, if at all.
0
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2answers
61 views

Times at relativistic speeds

Consider an observer $A$ moving in a spaceship at a speed close to $c$, relative to an observer $B$. The $B$ knows that the time on $A$ runs slower, but in the inertial frame of $A$, $B$ is moving ...
0
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2answers
65 views

Why do objects seem to move faster (relatively) when they move tangential to the observer?

I've observed this loads of times while travelling, in cars, trains,etc.I can't quite put it in words and therefore I've roughly made a diagram to assist my question. Assume an observer is travelling ...
3
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3answers
150 views

If nothing ever falls into a black hole, why is there a puzzle about information?

From an outside perspective, nothing can ever pass the event horizon. It just scooches asymptotically close to the event horizon. So (from our perspective on earth), when a black hole reduces in ...
1
vote
1answer
139 views

Possible Answer To The Double-Slit Experiment [closed]

I think I might have figured the double-slit experiment out. I am not going to explain it here, Google it if you don't know it. If I am wrong please tell me why: Matter are relative to observers ...
0
votes
0answers
29 views

How does a frame of reference work in relativity? [duplicate]

I am struggling to understand what frame of reference means in relativity. Imagine the twin scenario. Twin A is at rest, while twin B travels somewhere and back at near the speed of light. If one ...
1
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4answers
92 views

Special Relativity - travelling close to light speed

When we say something travels close to the speed of light, what is its speed relative to? For example, we have 4 highly advanced spacecraft at rest beside each other, labelled A, B, C and D. We ...
4
votes
3answers
348 views

A sees B's clock running slow and B sees A's clock running slow? [duplicate]

This paradox is very common it seems, in which A sees B's clock running slow and B sees A's clock running slow. Here is the question a little more concretely. Let's say B flies by A's spaceship. If ...
6
votes
3answers
248 views

Is energy content of a system different dependending on the observer?

For the sake of simplicity, let's imagine that the entire Universe is empty except for a single lump of (classical) matter with mass $m$. In its center of momentum frame, it is clear that the total ...
1
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1answer
83 views

Turning off point for 1g acceleration

Let's say I am on a ship accelerating with 1g. I want to keep the engine running for half a year ( to an observer from my point of origin ) but due to time dilation it would have to be sooner than ...
4
votes
4answers
464 views

What does observation mean in two-slit electron diffraction experiment? [duplicate]

My question is clear, that I ask: What do we mean by "observation" in 2-slit experiment for electrons (or any other wave-particle)? You know, we say that :"if we observe the electron, it shows a ...
1
vote
1answer
895 views

Time dilation - Earth & Jupiter [duplicate]

I have this doubt after watching Interstellar movie :) Lets assume I am in Jupiter. (I know it is a gas planet, full of hydrogen and helium, has extreme pressure etc. Lets please ignore those facts ...
0
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2answers
102 views

Consistent answers in special relativity [closed]

I was doing a question about if a train fits in a tunnel. From the train frame it does not and from the tunnel frame it does. Then the question asked are these two answers consistent? What does this ...
2
votes
1answer
89 views

About the relativistic wagon simultaneity problem [on hold]

I'm getting utterly confused with this problem. The situation is basically to know what events to take in one frame in order to see them synchronized in another. I sketched the situation as this: ...
0
votes
0answers
34 views

How does an observer in arbitrary state of motion assign numbers to events in a flat spacetime?

In a flat spacetime, there is an inertial observer, who assigns events coordinates in a usual fashion: Placing a clock everywhere and synchronize them. From his POV, the other observer is moving in ...
0
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1answer
67 views

How does “observation” affect physics?

I watched this video which very very comprehensively demonstrates concept that sometimes particles behave differently based on whether or not they're being observed. The idea that observing something ...
-2
votes
2answers
564 views

Why does time slow down when traveling at high speeds [duplicate]

One of the effects of traveling at high speeds is slowing down of clocks. I can understand gravity time dilation effect but not how would velocity affect clock speeds. How correct it is, if I say ...
0
votes
2answers
176 views

If a photon is exists in 'timeless' state, how can objects around it move? [duplicate]

My understanding is that light does not experience time. In attempting to understand what the universe would be like from the perspective of a photon, the answer I get is that the universe would be ...
1
vote
2answers
101 views

Does inbound light slow down (for an external observer) as it approaches the event horizon?

As I understand, for an external observer nothing even enters a black hole because it takes infinite time in his frame of reference for something to actually reach the event horizon. I also read that ...
5
votes
5answers
412 views

Formal definition of an observer?

What is the formal definition of an observer in special relativity? I have seen a few: The actual coordinate system. The collection of synchronised clocks that cover the coordinate system. A well ...
16
votes
3answers
2k views

Is it a postulate or a well proven fact that speed of light remains constant w.r.t any observer?

We usually heard that speed of light in vacuum $c$ remains same no matter how observer is moving? I am wondering whether is it taken as a postulate or a proven phenomenon that $c$ is constant ...
1
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0answers
34 views

In Quantum Physics would a camera count an observer that causes wave collapse? [duplicate]

Would the observation from a camera have the same effect on wave function as the observation from a living being?
1
vote
1answer
130 views

What wilI I observe when travelling at almost the speed of light? [duplicate]

If I and a group of friends are travelling at or just below the speed of light - can I see myself, can I see them, or they me? Would we see anything at all?
0
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1answer
58 views

How can we assume that reaching the speed of light slows down time? [duplicate]

How can we assume that gaining the speed of light slows down time?
0
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0answers
18 views

Conservation of energy with the change of observers

While trying to analyze a collision of two bodies, while considering the energy loss, I made this equation: $1/2m_1u_1^2 + 1/2m_2u_2^2 = 1/2m_1v_1^2 + 1/2m_2v_2^2 - W$ where $u_1$ and $u_2$ are the ...
0
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0answers
74 views

What does traveling close to speed of light mean?

This has been bugging me for a while. We all know in relativity that if you travel close to speed of light, all sorts of crazy things happen. But what does it mean to travel close to speed of light? ...
0
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1answer
71 views

Two quantum observers

It is considered that a quantum mechanics parameter is undefined until it is measured.But what happens if two independent observers measure the same quantum parameter? Do they get the same value or ...
23
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6answers
6k views

Should I abandon my thought experiment about time?

I'm trying to think about special relativity without "spoiling" it by looking up the answer; I hope someone can offer some insight - or at least tell me I'm wrong. Suppose I have an ordinary clock ...
4
votes
2answers
129 views

In the double slit experiment, what happens when there is more than one observer trying to see which slit the same electron goes through?

From all the demonstrations Iv been able to find of Heisenberg's double slit experiment, whenever an observer tries to "see" which slit an electron passes through it collapses the wave function. My ...
0
votes
2answers
30 views

How can I calculate the center of an object relative to a focal point and a moving observer? [closed]

I'm developing an app that contains a 3D scene which the user can navigate. As the user moves it gives the illusion that you are browsing a real landscape but for the illusion to work I need to know ...
1
vote
1answer
83 views

Special relativity: circumventing velocity-addition formula

Two spaceships approach an observer from an equal distance and from an opposite direction with an equal speed $v$ in the observer's intertial reference frame $O$. The speed of a spaceship in the ...
0
votes
5answers
628 views

A thought experiment in special relativity theory

We have two sets: set No.1 and set No.2 as in this picture: The observer is fixed to set No.1 . He sees set No.1 motionless and observes set No. 2 approaching with velocity 100,000 m/s. Each set ...
28
votes
5answers
3k views

What do you really see on a line of clocks as you pass by them at high speed?

According to my understanding of SR, if I travel at 0.8c relative to a line of clocks, I should see the clocks in front of me going 3 times faster than my own, and those behind me going 3 times slower ...
0
votes
3answers
338 views

A question about special relativity theory

We have two sets: set No.1 and set No.2 as in this picture: The observer is fixed to set No.1 . He sees set No.1 motionless and observes set No. 2 approaching with velocity 100,000 m/s. Each set ...
0
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0answers
16 views

Quantum observation in the double slit experiment? [duplicate]

As far as quantum observation, when a human observes electrons going through the double whole experiment, have scientist tried having a blind person observe the experiment to see if the electrons ...
1
vote
1answer
68 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 ...
2
votes
3answers
93 views

In terms of physics, does the phrase “time slows down” mean the same thing as “things happen more slowly?”

The common definition of "time" is a type of measurement, like size. But the sentence "size gets bigger" doesn't make any sense. Is "time slows down" an odd phrasing of "events occur more slowly" or ...
2
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4answers
133 views

How much could one slow down aging using existing spacecraft?

Imagine that I board a spacecraft and head away from the Earth at top speed until I've aged twenty years, then I turn around and come back. How much younger will I be than the unexciting folk who hung ...
0
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5answers
405 views

Why Light and Observers have different laws of physics [closed]

Special relativity states: The speed of light in a vacuum is always $c$, regardless of the velocity of the observer. The laws of physics are the same for all observers in uniform motion. These two ...
0
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3answers
149 views

Twin Paradox speed of light

Twin Paradox Can anyone clarify and or correct the following for me? A space ship is flying at speed v equal to 0.8 times the speed of light. Within the ship are three stations, a transmitter at ...