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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How is spacetime depicted in quantum field theory?

How is spacetime depicted in quantum field theory? Is space and time completely separate, and time is just nature of law as in Newtonian mechanics?
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59 views

Could it be theorically posible “cut off” a piece of space-time? [closed]

I know I may not have an accurate idea of what are the properties of space-time, but here is the idea: By doing an analogy with moving from 2 to 3 dimensions, I have been wondering if in theory it ...
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66 views

Is time a coordinate or a parameter in Newtonian mechanics?

In classical (Newtonian) mechanics we only ever seem to consider 3-dimensional space, with physical quantities being represented by 3-vectors. My understanding for this is because in classical ...
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46 views

2 space and 1 time dimensions [closed]

I know it is impossible to visualise a 3 space and 1 time dimensions. But what about 2 space and 1 time dimensions? Will it be like similar to 3 space dimensions or different? If different will it be ...
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54 views

Distorting the space-time fabric

If point masses could be generated in a controlled manner distorting the fabric of space-time objects could be made to move in any direction relative to each other and not simply attract as is ...
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37 views

Is turning space into time and time into space possible from an observer's perspective?

If the distinction between space and time depends on the reference frame, what reference frame should we use to perceive time as space and space as time?
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67 views

Black hole's singularity: Does it has to be multi-dimensional?

We assume that there is an infinite density at the center of a black hole. But we also know that if it was really infinite, it would apply an infinite gravitational force to masses even if they were ...
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74 views

Trouble in understanding spacetime

I have a problem in understanding spacetime. What i understood from the conversion of time to distance is that the interval between any two events is always the same for any observer. But how is that ...
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107 views

How can gravitational waves be detected when spacetime bends the instruments? [duplicate]

Apologies for the naive question, hoping someone with a proper physics background can explain this in layman's terms (as opposed to the more detailed answers at LIGO flawed by the identical expansion ...
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178 views

LIGO discovery: if the space “time” metric is changed, how is it measured? [duplicate]

Regarding the wonderful 2016 news about gravitational waves. Travel time in one arm of the LIGO is ~ 30μs. A gravitational wave affects the arm for some few hundred of these laps. Then for example ...
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73 views

Space-time and gravitational fields

I am reading a book by Carlo Rovelli, Seven Brief Lessons On Physics, and would like to check if I have understood something. Apologies if my question is badly phrased, feel free to edit where ...
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51 views

Empty space and velocity

If there was a universe without anything in it except you in a space rocket how you would you know what your velocity if you kept the engine on?
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118 views

Is causality a total order?

I've read that it is physically not possible to violate causality defined as a total order on the spacetime graph. So I was wondering if at least causality can be broked down to a partial order and if ...
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53 views

See behind the black hole

Why in this video does the 2nd black hole appears to change size and appear larger the farther away it gets? How can you see behind it? http://www.youtube.com/watch?v=ENd8Sz0AFOk
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109 views

What is the basic concept of four-dimensions in physics?

I have been reading a few books lately and browsing the internet for an explanation on the concept of "four-dimensional" space (or, space-time, as some of them have been calling it). But, what those ...
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81 views

Are there continuous spacetime events?

What is the formal definition of an event? According to Wikipedia, "an event is a point in spacetime (that is, a specific place and time) and the physical situation or occurrence associated with it." ...
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42 views

Calculate the relativity of time of an event occurred in different frames

Imagine we have a train which is moving with a velocity and there's an observer inside of that train and there is an observer that is outside of the train observing the train moving. There's a ball ...
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106 views

Is presuming that any linear uniform motion is transformed into another one sufficient to assume that Lorentz transformation must be linear?

I've read this condition in a script: The Lorentz transformation must be linear because any uniform motion must be a uniform motion in any inertial frame. All other proofs that I've read so far need ...
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112 views

Time dilation: linear or exponential or other?

As you near the speed of light, time slows for you relative to the world around you. So you would be traveling at more than one hour per hour. Is the rate of time slowing for you linear or exponential ...
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100 views

Frame dragging in general relativity versus classical vorticity concepts

Can anyone please clarify what one means by a vorticity in Space-Time? I'm aware of the vorticity in Fluid Mechanics. Is it the same vorticity that appears in General Relativity? Is vorticity related ...
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94 views

Does spaghettification really happen with conditions found close to a black hole?

This website tries to explain why the term spaghettification doesn't actually occur when something gets close to a black hole. The argument of the author is that the equations we use to predict the ...
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On a graph, can the compositions of both the x and y variables involve the unit time?

Time seems to be so fundamental to the calculations that we make, that it seems to be at the core of everything we do. Indeed, this is not just philosophically true, time is very often the x axis, by ...
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1answer
79 views

Understanding the nature of metric tensor [closed]

The metric tensor for a flat spatial manifold gives us length on object, or separation between two space points. Similarly, $g_{\mu \lambda} dx{^\mu} dx{^\lambda}$ gives separation between two space ...
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274 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. ...
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153 views

Space: a vacuous void or an entity?

I am a chemist and, until recently, a senior Research Manager with a major chemical company. Please excuse the potentially naive ramblings of an idiot in what follows, but I do not have the ...
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134 views

Infinite halving of a distance

If an object is, say, 100 cm. from a wall, and I move the object halfway to the wall and stop, then the distance is reduced to 50 cm. If I continually move the object by one half of the remaining ...
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66 views

Is a black hole really a hole in space? [closed]

What if when a supernova occurs, instead of it condensing into a singularity it creates enough force to tear a hole into the fabric of space? Is a black hole just what is sounds like, a hole in space? ...
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189 views

Are a black hole really connecting 2 parallel universe?

What is beyond the point of singularity in a black hole and universe expands in all the 3 $x$, $y$ and $z$ axis? So how can one thing be on top of another when we don't know where the end point of ...
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92 views

What logic did Newton give in support of using relative spatial measurements? [closed]

The crux of space-time is that it is one thing to have abstract concepts of absolute space & time,and it is other thing to describe the actual motion of an object in terms of measured changes of ...
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125 views

Spacetime Metrics and Quantifying Length of a Spacetime Curve

On page 247 in Gravitation by Misner, Thorne, and Wheeler, they state: "No metric means no way to quantify length; nevertheless, parallel transport gives a way to compare length!" Three questions: ...
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54 views

Higgs field and the null geodesic

How does coupling to the Higgs field take a particle with a spacetime interval of zero and give it a non-zero value, i.e, how does it move it off the null geodesic? [of course, the Higgs field is ...
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137 views

Timelike curves in Special Relativity

I have a question that probably might sound silly to most of you. We know that a natural Lorentz-invariant parametrization of a timelike curve is provided by: $$\tau$$ the Lorentz-invariant proper ...
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1answer
377 views

Can someone explain effects of time dilation on expansion of universe [duplicate]

I'm not a physics guy, but this is something I have always wondered about. If a clock flown by an object of high mass runs slower, what is the effect of this in regards to the density of the universe. ...
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141 views

Is proper time an intrinsic value of Minkowski space?

What is proper time? Is it a part of Minkowski space (that is a mere spacetime interval)? Or is it an intrinsic characteristic of massive particles (a sort of "aging")? Example: In the following ...
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149 views

Space distance between observers and Lorentz transformation

I'm not a specialist of Lorentz transformation. I would like to know if the Lorentz transformation from one observer to another preserves the space distance between these two observers. Example ...
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219 views

Is there no fourth dimension (time) in the universe? [closed]

In this article (and numerous others) http://phys.org/news/2011-04-scientists-spacetime-dimension.html and http://www.rebelscience.org/Crackpots/notorious.htm they suggest that there is no time ...
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123 views

Why could you not travel back in the time before a tipler cylinder is created?

Is it because the lightcones are not tipped all the way over in which the time axis points downwards?
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174 views

Understanding emergent phenomena in the block universe. (Reworded question)

Each person exists as an unchanging 4D worldtube in the block universe. At each slice of the worldtube there is a present, past and future. However, there is a black box* which appears to exist in ...
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89 views

How does someone move space?

I've heard that we've known components of the universe appear to be flying apart faster than $c$, and that this can happen because the space containing these materials are also moving apart. How does ...
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453 views

Do photons see shorter distances due to space contraction?

I may be wrong, but this is just what I've heard. People often talk about what would happen if we, humans, were able to make a spaceship travel at the speed of light. If I'm not mistaken, then we ...
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520 views

Can light exist without spacetime?

Since the medium in which light propagates is spacetime, would light be able to exist if spacetime did not exist? Is this like one of those chicken/egg problems, or can light be thought of as a ...
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257 views

What is the link between the metric signature of spacetime and fundamental field equations?

The signature of Minkowski spacetime is 2, as is explained here: metric signature explanation. The signature is related to the form the fundamental equations take, but I'm not totally clear on the ...
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86 views

Is the spacetime interval between the Big Bang and a given event dependent only on the time component?

My thinking is this - at the time closest to the Big Bang when physics doesn't break down, the universe would have had a volume that was still very close to zero. If that were so, wouldn't the space ...
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1answer
593 views

Time dilation at the speed of light

Does a massless particle travelling at the speed on light in a vacuum (c) experience an infinite time dilation effect? i.e. Would the time dilation extend from the perspective of the massless ...
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1answer
202 views

Is relativistic motion equivalent to fluctuating gravitational fields?

The theory of relativity makes very precise predictions about how an object's motion through space-time affects the passage of time for both the object and observers in other frames of reference. I ...
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1answer
601 views

When are we now? Time coordinate system [closed]

The Second and the metre are well defined. We have those units available. Of course units are meant to express measurement, tools to compare with precision, and interchange that information ...
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33 views

About relativity [duplicate]

We know that the curvature of spacetime is gravity itself and it is not a force.so,why do we feel our weight in a curve spacetime but not in a straight(I mean not curve) space time like zero gravity ...
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58 views

Why does two masses with energy attract each other?

I have heard that every mass attract another mass with a force directly proportional to the multiplication of their masses and inversely proportional to the square of distance between them, but newton ...
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113 views

How to interpret Hermann Minkowski's comments on the construction of spacetime

What did Minkowski mean by his statement: "The views of space and time which I wish to lay before you have sprung from the soil of experimental physics, and therein lies their strength. They are ...
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33 views

If black hole is a “hole”, how can its position be pinpointed from every position in universe? [closed]

Ok, this is going to sound lame but, here goes: When we say that a black hole is situated at a distance of 1 light year(let) FROM EARTH, that means it may situated at a distance of 100 light years ...