As a consequence of the Lorentz transformations, time and space transform into each other when changing reference frame. This calls for a unified description: Minkowski spacetime.

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Is time quantised? [duplicate]

What I think is that time must exist in unit quanta as we find the speed of light to be the fastest possible, if time were continuous there would be a possibility that there be something faster than ...
4
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2answers
128 views

Commutation relations in QFT and the principle of locality

My question is, given two space-time points $x^{\mu}$ and $y^{\mu}$, if the events that occur at these points are simultaneous, i.e. $x^{0}=y^{0}$, are the two events necessarily space-like separated? ...
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24 views

relations opf space-time to gravitation as an evolutionary process [on hold]

just thoughts - 1 -gravity - could it be that it is not a fundamental force after all - could it be that it evolved after the big bang? space time was evolving and things [lets call them string but ...
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3answers
104 views

Speed as the fifth dimension

In spacetime there are four general dimensions, three of space and one of time. Why is it that other dimensioned qualities seem to be rarely considered as part of spacetime? For example, why isn't ...
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0answers
42 views

Matter originated out of space? [on hold]

Is it possible that matter has originated through space out of imbalance of space? If yes then is this event same as big bang? Also is it possible that there are multiple non-interfering big bangs? ...
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71 views

Is Einstein still alive? If so how can I talk to him? [on hold]

Einstein said that time is the fourth dimension. So if I wanted to chat with him all I would have to do is send information in a temporal direction, instead of for example down a telephone cable? ...
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0answers
29 views

In discrete models of spacetime, what are some implications of the Einstein equation

We have several models of discrete spacetime. Sorkin has a causal growth dynamics, there's spin foams, Panangaden showed a correspondence between interval domains and spacetimes. I am looking for ...
3
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2answers
111 views

Can anyone explain me how time can bend according to Einstein in simple way? [duplicate]

I am just 16 and curious to learn about Theory of Relativity. Can any one explain it simple enough for me to understand? I read that it is bending of time-space or space-time that causes gravity. How ...
2
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1answer
109 views

Does all of spacetime exist?

In Brian Greene’s 2004 book, The Fabric of the Cosmos, he quotes Einstein on the meaning of time, …the distinction between past, present and future is only an illusion, however persistent. ...
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1answer
64 views

Does isotropy imply homogeneity?

This question comes from exercise 27.1 in Gravitation by Misner, Thorne and Wheeler. They required the following: Use elementary thought experiments to show that isotropy of the universe implies ...
2
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1answer
65 views

Do gravational effects 'travel' through a wormhole?

Lets say a wormhole exists with point A inside the gravity well of a star and point B in a space where there is no notable nearby mass to create a gravitational force. If one were to approach point B, ...
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1answer
62 views

Calculate Time travel with Time Dilation [closed]

Does the following hold: If we have: person A moving at a speed of $0$; person B moving at a speed of $xC$ (where $C$ is speed of light, $x$ a fraction) And if time passes for $m$ ...
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Is the fourth dimension of Minkowski Spacetime viewed as an axis? [duplicate]

In the three axes of space, I can move in a positive or negative fashion, up or down, side to side, etc. Why is this not the same for the axis of time, if it is an axis? If it's not an axis, what is ...
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1answer
33 views

Is distance always 0 relative to an object moving at speed of light $c$?

As I understand it, when an object is traveling at the speed of light, relative to itself all travel is instantaneous and the distance is zero. If a photon traveling from the sun was aligned with the ...
2
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4answers
798 views

When space bends, what are the lines that are being bent?

In an electric field diagram, the lines represent the electrostatic force vector at the position. These lines are bent when you place a charge into the system. What is the equivalent description ...
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3answers
87 views

How can you explain objects of unequal masses falling at the same rate using GR?

Isn't gravity caused by the curvature of space-time, and the stronger it's curved the stronger the attraction? it makes more sense to me that if a heavier object is falling on earth it would fall ...
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2answers
196 views

How can the universe be flat?

Okay, so I just want to clarify a few things. According to what I have read, we have measured the universe to be flat, and the shape of the universe is directly related to the mass-energy density. ...
2
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1answer
342 views

What happens to the total volume of a chunk of space that is being sucked into a black hole?

Does it increased, decrease, or stay the same? Maybe it explodes to infinity... Here is a similar question: Do black holes have infinite areas and volumes? But it's different because it asks how to ...
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3answers
106 views

Closed timelike curves in the region beyond the ring singularity in the maximal Kerr spacetime

The region beyond the ring singularity in the maximal Kerr spacetime is described as having closed timeline curves. Why and/or how is the question. Now if you look a Kruskal-Szkeres Diagram (or a ...
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1answer
73 views

Do Einstein's equations allow multiple solutions that agree in a neighborhood of a spacelike hypersurface?

This question is an extension of my a question that I have recently asked: Why doesn't a global frame of reference exist for GR?, where it was recommended that I post another question (so I am ...
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2answers
136 views

Why doesn't a global frame of reference exist for GR?

I only have at best a layperson's familiarity with GR, so forgive me if I am asking a basic question, but I have heard that in GR, we cannot have a global frame of reference, that is a frame of ...
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1answer
46 views

Is a planets orbit really a straight line through curved spacetime? [duplicate]

My understanding is that general relativity concludes that gravity isn't real because it does not exist in all frames of reference. Also that mass and energy warp spacetime into a curved geometry. ...
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2answers
63 views

Meaning of Proper time

Sorry for a bit of a basic question, but want to clarify things in my head. Is proper time quantified by the amount of physical process that an object, or physical system undergoes, for example the ...
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1answer
62 views

Can gravitational waves carry momentum, and if so what mass/energy produces it, and is space-time capable of vortex formation?

This question is about gravitational waves postulated by Einstein. Is gravitational radiation a form of mass/energy that can form momentum? If it causes ripples in space-time, would space-time ...
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0answers
92 views

Basic doubt on the philosophy of Quantum field theory and General relativity

As I understand, the basic idea of General relativity is that the 4-d spacetime is "deformed" because of the presence of matter-energy, in other words no pre-existing (or background) space is assumed ...
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51 views

Does time exist in the universe? [duplicate]

Does time start with the start of our universe, or doesn't it even exist? It is either fundamental in our universe or it is just invented by us for our ease.
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3answers
107 views

Does it make sense to model the Universe from an outside perspective? [closed]

I was reading some questions and answers about black holes and whether matter can actually pass through the apparent horizon, in particular this one: How can anything ever fall into a black hole as ...
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0answers
69 views

Does negative mass reverse the arrow of time?

General relativity predicts that normal mass (positive mass) results in the curvature of spacetime which in return leads to gravitation. Since space and time are bonded together, any change on the ...
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0answers
41 views

If you have two Planck lengths extended from one point forming a right angle, whats the length of the hypotenuse? [duplicate]

Can we do measurements at this scale seeing that the length of the hypotenuse would have a value at a length that cant exist (1.4 Planck lengths)? Or is my interpretation of the Planck length ...
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5answers
128 views

How to explain space-time curvature in two minutes? [closed]

How would you explain what is the curvature of space-time in a short period of time like 2 minutes to non experience people?
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1answer
31 views

Calculating curvature of spacetime when energy is present

I am only about half-way of studying SR and GR and I am not yet familiar with a formula to calculate the curvature of spacetime when energy is present. To be more specific, I want to calculate ...
1
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1answer
59 views

Understand the relation of time and the space dimensions of spacetime?

I assume the relation of the three spacial dimensions and the time dimension is handled purely in the mathematical domain, usually. But is there any intuitive description of this relationship, how ...
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1answer
75 views

Has infinity been observed yet?

Has infinity been observed yet? Or in other words. Does infinity actually exist or is it just a concept? Is it just another way of saying very or extremely?
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2answers
81 views

What's outside of the universe? [closed]

Assuming you found a way and managed to accelerate above light speed without disintegrating, and went to the edge of the universe, what would happen? Would you instantly explode due to the lack of ...
37
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3answers
6k views

Is the Planck length the smallest length that exists in the universe or is it the smallest length that can be observed?

I have heard both that Planck length is the smallest length that there is in the universe (whatever this means) and that it is the smallest thing that can be observed because if we wanted to observe ...
1
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0answers
50 views

Why do we hyperbolas for distance? [closed]

I'm confused about how distance is measured in spacetime. I've read a few texts that say that our normal distance equation doesn't apply because it violates causality and because it won't work for a ...
0
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1answer
44 views

Influence of spacetime curvature on electromagnetic wave propagation [duplicate]

Classical physics assumes that spacetime is evenly distributed in the sense that Coulomb's Law predicts that a charged particle will create a spherically symmetric electric field around its location. ...
9
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3answers
242 views

What is the exact meaning of homogeneity in cosmology?

I understand that, in general, homogeneity is the physical attribute of being uniform in composition (" of the same form at every point"), but I'm slightly confused when it is used in cosmology as ...
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2answers
29 views

What does “simultaneously” mean in relation to a detonation shockwave?

I understand that the difference between a deflagration and a detonation is that the reaction front of a detonation moves faster than the speed of sound in the material, which means that the pressure ...
3
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3answers
197 views

How does warped space actually look (visually)?

Recently, I was reading about space warping due to extreme gravity and at speeds approaching c, but in books, they always show space in 2D and depth to show space distortion. I was wondering how ...
3
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1answer
43 views

Do we weigh more when standing near massive buildings?

I'm very new to the concepts of SR/GR and curvature of spacetime. My understanding is that the bending of spacetime is the causation of gravity, and that matter is the causation of the bending of ...
11
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4answers
2k views

Does General Relativity imply loops in space?

Everyone who has been interested in modern science has heard explanations (certainly simplifications) of general relativity, mostly that space is curved. The analogy with a rubber sheet is popular. In ...
1
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0answers
59 views

Is it possible for someone traveling at the speed of light to see at all? [closed]

I know that the speed of light is the same for all observers regardless of your speed, But this question is really worth thinking about. If someone let's say managed to reach the speed of light, ...
0
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1answer
57 views

How far can you propagate something, anything, before it becomes 'background noise'?

An electric field, light, a movement of molecules; anything at all. What is the maximum distance they can go before they are 'noise' to an ideal measurement instrument? So if the distance is ...
2
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4answers
58 views

Is there a maximum accuracy for positions in the universe?

I was thinking how, since an object in our universe can move from one position to another, it must have passed through all the positions between those two positions. (I am thinking it moved it a ...
8
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2answers
563 views

Momentum and spacetime

My apologies up-front for the naive question and my rudimentary understanding, but I should be delighted if someone would enlighten me :) The question has to do with the application of the ...
0
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1answer
41 views

Observers in different planets viewing each other

I'm a newbie to relativity, so If the question is idiotic, please excuse me. My question is, as in Interstellar movie suppose one person is sitting in a planet A whose 1 hour equals to 6 years of ...
2
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2answers
63 views

Watching a LIVE stream in spaceship traveling away from earth close to speed of light

My name is Dennis. This might sound just straight up ignorant of basic concepts of physics. I was having a conversation with my friend in regards to streaming a LIVE event on earth to a spaceship ...
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1answer
65 views

Light speed time distortion

From my understanding objects moving close to the speed of light experience a time distortion in that time moves slower and slower as they get closer to the speed of light. If that is the case ...
0
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1answer
66 views

Fibre bundles and space-time

I'm having some trouble understanding the concept for this more than likely due to my lacking mathematical background. I am currently reading Roger Penrose's The Road to Reality page 394 ...