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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5answers
105 views

How to explain space-time curvature in two minutes?

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
23 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 ...
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0answers
37 views

My own thoughts about singularities and spacetime [on hold]

I believe the assumptions about black holes are mostly wrong due to the idea that time dilates relative to an outside observer as you get closer to the singularity at the center of the black hole. ...
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0answers
28 views

How to make wormhole? [duplicate]

Today in my physics class, my teacher gave us an introduction of relativity and I found this very fascinating. He said that it's very hard to make a wormhole because it requires a lot of energy. I am ...
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1answer
46 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
61 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
75 views

What's outside of the universe? [on hold]

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 ...
31
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2answers
5k 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
48 views

Why do we hyperbolas for distance? [on hold]

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 ...
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1answer
41 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. ...
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3answers
200 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
26 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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1answer
40 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 ...
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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
51 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
54 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
53 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
548 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
33 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
49 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
57 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 ...
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1answer
58 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 ...
1
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1answer
80 views

Is cause-effect always preserved in relativity?

I guess most of you are familiar with the "paradox" of the train passing through a tunnel smaller than itself on a speed close to the speed of light and 2 guillotines (1 in the exit and 1 in the ...
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2answers
77 views

Can gravity be interpreted as the acceleration of spacetime towards an object? [closed]

Greetings StackExchange! We were having a conversation with a peer about stupid ways of interpreting theories. We would go to and fro with an interpretations, but we would always find a way to ...
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1answer
38 views

Light trajectory

We have observed stars where "we should not" Some people say that gravity can alter light trajectory. Some people say that gravity actually alter the space on which light travels. Which one is ...
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0answers
15 views

Is there a “framerate” for the universe? [duplicate]

I've been wondering this for quite some time. I just can't wrap my head around the idea of truly continuous time. If time is truly infinitely divisible, then how can any object in the universe move? ...
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1answer
107 views

Planck length paradox [closed]

This is a paradox I thought of a few days ago, and I wanted to ask whether it makes any sense and where the mistake is. We know that the nothing but light can move faster than light itself. So in a ...
3
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2answers
53 views

Is spacetime absolute?

As I understand it Newton's Laws imply that space is relative, as the laws of physics are the same in all inertial frames and as such there is no way, even in principle, to distinguish a frame that is ...
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2answers
335 views

Age of the universe and the singularity at the Big Bang

Using the standard model of cosmology we calculate the Hubble time to obtain an estimate of the age of the universe. This model assumes a beginning of time in the past. But that point is a true ...
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1answer
30 views

If there are any discernible effects of travelling through curved space..?

If one is on a spaceship traveling through a 'very' curved section of space-time, are there experiments one could perform on the ship that would reveal measurable differences between the very curved ...
3
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1answer
116 views

How warped spacetime bends trajectories of light and moving objects?

I fail to see why the light follows something like the blue line and not the green line on the attached image. Figure 1 - light bends around warped spacetime Afaik. something similar happens ...
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1answer
73 views

Traveling faster than the universe is expanding?

I was thinking, if the universe is space and time expanding, lets say in 3D (like a sphere). And it is doing that in a constant or not constant speed, there is a debate about that, never mind that but ...
0
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1answer
58 views

are spacetime and gravitons one in the same? [closed]

I ask because it seems to me with my admittedly limited knowledge that this doesn't necessarily contradict any widely accepted theory. In fact it would help explain a few incomplete theories. Does ...
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0answers
138 views

Is the Milky Way's halo curved spacetime? [duplicate]

This question has nothing to do with dark matter. This question is discussing a theory which states the notion of dark matter is incorrect and the Milky Way is moving through and displacing the 'dark ...
3
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3answers
78 views

space contraction near lightspeed

I read a lot of the Time-Life Science books when I was a kid (well, mostly the pictures and captions). One of the things that always stuck in my mind was an explanation of the twin paradox, using ...
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0answers
39 views

Can you communicate future information through the event horizon?

According to Hawking on "Particle Creation by Black Holes", there exists a relationship between the entropy outside of an event horizon, flux within the event horizon, and the area of that same event ...
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2answers
282 views

When will physics understand it is the 'dark mass' not the 'dark matter'? [closed]

There is new thinking occurring in physics where 'dark matter' is considered to be incorrect. The new thinking is that mass fills 'empty' space. The mass which fill's 'empty' space is being referred ...
1
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1answer
73 views

Could time be considered a force

I think I understand the basic concept of spacetime, at least some of it. And when people talk about spacetime they don't call gravity a force, but rather the result of mass interacting with it. And ...
21
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1answer
2k views

Why haven't we seen the big bang?

The Andromeda galaxy is 2,538,000 light years away, so if we view Andromeda from a telescope, we see Andromeda how it was 2,538,000 years ago. Now the diameter of the visible universe is 92 billion ...
1
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1answer
46 views

Flat universe a torus?

As shown by cosmologists space is presumably a flat expanse. In his book the Fabric of the Cosmos, Brian Greene shows that one of the possible shapes of this flat universe is a Torus. My question is, ...
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1answer
56 views

Can we travel faster than the speed of light? [duplicate]

So my question is completely a theoritical question. For example i have a stick made of the strongest material and lightest material and its lenght is as long as the solar system's diameter. The end ...
0
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2answers
59 views

Why should I believe that matter does not expand along with the space between it [duplicate]

This question has been asked before under other guises. I am not a scientific profesional however i have some schooling in pyhsics and mathematics and have a keen interest in these subjects. It seems ...
1
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3answers
127 views

Is a black hole a 3D hole? And doesn't it pull into the 4th dimension?

Hear me out here please: A body on a line (a 1-D world) causes a warp in the line, i.e. a curve (2-D) A body on a plane (a 2-D world) "sinks", causing a warp in the plane, i.e. a pit (3-D) Then does ...
3
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2answers
94 views

Can a hypothetical universe have more than 2 types of dimensions: spatial and temporal?

Our universe is often described as having 3 space-like dimensions and 1 time-like dimension. Can hypothetical universe exist with more than space- and time-like dimensions? If so how would these ...
-5
votes
2answers
92 views

Is it possible to travel ONLY through Time and not Space? [closed]

The question is as stated above. I although think, the most probable answer is no, but I really want to know the reason to it. If, One can travel through only space by travelling at the speed of ...
0
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1answer
135 views

Is time an illusion? [closed]

IS time an illusion? I have tried thought experiment after TE and quite frankly I can't find any instance where time is defined wholly on its own. It is always a measurement of the interim between to ...
0
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1answer
51 views

Time relativity / paradox [duplicate]

After watching the movie Interstellar, the theory of time relativity / paradox really mind-boggles me. If it is true that gravity controls everything even to the extent of time, then it might as well ...
3
votes
1answer
113 views

What are the photon/electron consequences of matter in a gravitational time dilation?

So I saw the movie Interstellar, and it got me thinking. I won't even mention all the plot holes, but I wanted to ask about a planet orbiting a black hole. I always thought you had to travel near the ...
0
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1answer
74 views

Are we really sure that the whole universe is expanding?

Haven't we thought about the possibility of only a region of the universe is expanding? What about space is expanding in this region and space is compressed in another region, that satisfies the ...
3
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1answer
68 views

The actual space curvature

What is the curvature of our physical space, according to the latest experimental data? I've found it somewhat difficult to find a definitive answer to the question, because the spacetime curvature ...