Questions regarding the 4-dimensional background structure of our universe.

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Spinning black hole vs non spinning black hole

Does a spinning black hole have a stronger gravity than a non spinning one.After all, a spinning black hole is stretching space-time more, so does that make a difference is gravity?
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1answer
37 views

Can a black hole rip spacetime

Can a black hole which has an enormous mass and spins so fast cause spacetime to to be stretched to is absolute limits that it start so rip?
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1answer
18 views

Measuring time and distance in space

When reading through articles about discovering gravitational waves, I got basic understanding of events that happened. But one thing wasn't clear for me. They say that two black holes collided 1.3 ...
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0answers
20 views

Time travel possible? [on hold]

I once saw on television that if we focus all the light of our sun to a specific point which might create some kind of hole, than we might be able to time travel ( I don't understand how) or if we ...
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0answers
33 views

Is there an objective difference between space expansion and reduction in speed of light

I just read an article about the cosmological model of an inflationary universe. As you probably know it basically states that space itself is subject to an expansion over time. Since there is no ...
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0answers
52 views

How would FTL travel appear through window of ship? [migrated]

How would faster-than-light travel appear through window of a space vessel? All the movies and TV shows like Star Trek and Star Wars seem unrealistic: Star Trek credits: passing stars get bigger ...
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1answer
43 views

When I read that a system is located x light years away, why is there no direction?

Well, I just read an article about a galaxy with two black holes, and it stated that the galaxy is 1 billion light-years away. Why is there no direction given? If the Big Bang happened, and things are ...
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1answer
71 views

Question about space-time

In the big bang model of the Universe, every observable thing is thought to have expanded very abruptly from a point of infinite density and zero volume. However, the problem with this assertion is ...
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2answers
73 views

Center of the universe

Big bang is not an explosion, but an expansion of space and time. Universe had almost infinite density... wait a moment. If it had ALMOST infinite density, it had a certain volume, and thus, space ...
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2answers
129 views

A camera and time dilation?

If I travelled near a black hole, my time would progress slower relative to someone on Earth. This is clear enough. However, what if we sent a probe with a camera to a black hole? When we watch the ...
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3answers
195 views

Why can't gravity repel things?

Gravity is the result of the curvature of space, so could the curvature actually send objects away from the source?
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2answers
137 views

Does spacetime return to being flat?

I wrote an experiment in HTML5 and Javascript to try to show what is happening to the curvature of spacetime as a body moves through a region. As time progresses, I'm using the ...
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2answers
72 views

Is time itself speeding up universally?

Time moves more slowly near a mass than in relatively empty space. For example, I get that an observer would see someone falling into a black hole to appear to move more slowly and get "stuck" on the ...
2
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2answers
114 views

Does all of time exist and if so where is it?

I've recently learned about the theory of relativity and time. I'm trying to understand it more. My (basic) understanding is that there is no distinction between past present and future and that ...
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0answers
27 views

Does all of time already exist if so why can't we see it? [duplicate]

I've recently become fascinated with the theory of relativity and time. If all of time already exists, and there is no difference between past, present and future then what is preventing us from being ...
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1answer
45 views

Could the Earth use gravitational lensing / bending of light to see it's own bottom?

Specifically, I have often wondered whether gravitational lensing might be able to (theoretically) be used in order to see light reflecting off the Earth that has zoomed off into space and been bent ...
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4answers
117 views

Does time slow down because the universe is expanding at an accelerating rate?

If the universe is expanding at an accelerating rate, such that the galaxies' moving away from each other is accelerated, then time should also slow down. And when universe will accelerate to the ...
2
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1answer
70 views

A universal reference point [duplicate]

I would like to use a system of co-ordinates (x,y,z,t) based on a specific well known point. My original choice (the center of the universe in the big bang theory, Bigbang0), was wrong as the universe ...
2
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0answers
35 views

nasaworking on a way to travel faster than speed of light [closed]

even if they did how will time pass in that ship. Also that ship would require a infinite amount of energy to fight the drag.but what would provide the drag since in space there is nothing to resist?
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1answer
42 views

Is the time lapse considered when estimating the age of the universe?

We say that our universe is 13.7 billion years ago. During the big bang, it doubled at least 90 times in trillionth of a second (as given here), and other topological statements. The question is ...
2
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1answer
115 views

Can we see Earth by looking into space?

It is known that spacetime is curved,so I am wandering to know if its possible to look into space and we see earth (light from earth long long ago). Did I understood spacetime correctly and if its ...
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2answers
107 views

Space time and aging

Would a more significant curvature of spacetime relative to earth (i.e. time on jupiter) effect the aging process? Basically would you age at a slower rate? Or age faster on the moon?
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1answer
206 views

Time according to the gravity of Sagittarius A?

This may be a really dumb question (I'm more of a Biologist than an Astronomer) so I apologize in advance for my little knowledge pertaining to Astronomy, but, if I'm not mistaken, time is effected by ...
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1answer
214 views

Why does Earth have more gravitational force than the Moon if I stand on it?

Perhaps this is a silly question but I am trying to understand Einstein's general theory of relativity. I would like to explain my question in more detail. The greater the mass of an object, the ...
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2answers
72 views

How was all the matter curled up inside a singularity during big bang ?

If the singularity had infinite mass, temperature and density, then it should curve space and time but there was no space-time before big bang. So where did the singularity come to existence without ...
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1answer
23 views

Do astronomers, in principle, have more information about older phenomena than younger?

The further away we see, the older states of the world we observe. And the volume of the part of space which is observable, increases by the square of the distance to it. So there should basically be ...
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4answers
285 views

Light Cone Explanation

Not sure if this question belongs here, or on Physics. Would someone please describe the "anatomy" of a light cone and provide an intuitive example? I have read the Wikipedia article ...
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2answers
86 views

The multiverse spacetime paradox?

If there are indeed multiple universes, where do they exist? We "know" that outside our universe, consisted of spacetime, there is nothing - i.e. 0 dimensions, no space and no time. So "where" are ...
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1answer
115 views

What it would look like to observe people with a different time flows?

As I learned, that the bigger gravity source you are influenced by the more slow time ticks for you, the farther away you are from a gravity source the faster times ticks. So Imagine two different ...
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2answers
310 views

Why does the distance between Sun and Earth stay the same?

Well, we all know Sun gravity , makes the Space time curvature and space pushes the earth towards the Sun. But my question is "why the distance between the Sun and Earth is Same? Earth should have ...
3
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2answers
256 views

time on earth compared to completely stationary in space

I recently started trying to understand the theory of relativity and I have the following question. Because earth is orbiting the sun at approx 67,000 mph (and its my understanding time slows down ...
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1answer
93 views

How would Special relativity explain past-present-future if thinking about 13-billion-light-years distanced objects

Halo. I'm interested in how would Special relativity comment on this: Suppose there are 2 objects, A and B. They are 13 billion light years away from each other. When the light from the B object ...
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2answers
980 views

Age of the universe and time dilation

Given our knowledge and the standard cosmological model, we estimate that the age of the universe is about 13.7 billion years old. How much sense does it make to talk about the age of the ...
3
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3answers
1k views

What is the relative time difference between us and a star system in outer layer of our galaxy?

Just curious to know what will be the time difference between someone living on the outer layer of our galaxy and us, considering the known facts that Time is relative to gravity Our sun goes around ...
2
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1answer
53 views

World line coordinate finiteness

If you trace two particles' world line backwards in time, according to current theory, both objects should converge at big bang. Would both objects arrive there simultaneously? Another way of asking ...
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1answer
71 views

the length of second, minute or hour, what defines the time of exo planetary bodies

we measure time based on earth and earth mass\gravity plays a role in the measurement ? so how and what would be time if not earth time on other exo planets since they will be having different ...
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1answer
138 views

How is space-time bent by black holes?

I just read When a star becomes a black hole, does its gravitational power become stronger? and it confused me a bit; I always thought black holes are supermassive and that is why they bend ...
4
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1answer
69 views

Perception of an objects history passing as an observer moves toward it

If a star is 20 light-years away and I look at it through a telescope, what I'm observing is what the star was doing 20 years ago yes? So, if I fix my sight on the star and move toward it (for ...
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2answers
189 views

Why doesn't this paradox disprove (some) multiverse quantum gravitational theories?

As I understand it, one theory of the multiverse is that there are an infinite number of universes separated by small distances in other (than our observable 3/4) dimensions and that gravity is weak ...
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2answers
218 views

What is gravity really?

What is gravity? I want to know more than it being simply the "mysterious force" that attracts things to earth. Is it a particle, a wave, or something else entirely?
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1answer
135 views

Can Space-Time Itself Have Energy Qualities Like Momentum?

Hypothetically, if space could be moved or scaled, what would happen to everything inside? I'd like to know if an element of momentum could be transferred to objects by contorting space-time. Other ...
4
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1answer
2k views

Would time go by infinitely fast when crossing the event horizon of a black hole?

If you were to fall into a black hole, my understanding is that from your reference point, time would speed up (looking out to the rest of the universe), approaching infinity when approaching the ...
3
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1answer
81 views

Taking Advantage of Time Dilation

According to Einstein's theory of Special Relativity, one's speed in relation to a relatively stationary object would 'slow down' time on the moving object. With this in mind, would it be possible to ...
2
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1answer
188 views

A day in earth, a thousand years somewhere else

By followig the laws of physics, is it possible, that in a place far far away that one day (at that place), is counted as 1000 years in the earth. I am familiar with black holes having impact on ...
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3answers
859 views

Does matter accumulate just outside the event horizon of a black hole?

My understanding is that time slows and approaches stopping when approaching the event horizon of a black hole. I have seen this explained several places, including a brief explanation in the last ...
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1answer
76 views

How often do stars form?

There are many more stars in the universe than the years that the universe has been in existence, so wouldn't this mean that stars were/are forming at an astounding rate?
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3answers
369 views

What shape are black holes theorized to be?

I have always been curious about what black holes (or their event horizons) would look like if we could directly observe them. I notice that they tend to be depicted as flat holes in space but it ...
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3answers
457 views

What is a singularity? What is at the center of a black hole? Specifically regarding space-time

So because I can only really think of space-time in 2-dimensions like a sheet of something, my assumptions might be wrong to begin with. I was watching a YouTube video on black-holes and there was a ...
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2answers
133 views

Questions about time and space (from beginner)

To be honest my knowledge about astronomy and related physics is close to zero. However, since I studied math a bit, I would like to ask a couple maybe stupid questions, which I am curious about and I ...
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2answers
1k views

Our universe the surface of a 4-dimensional sphere?

The cosmic microwave background that we observe uniformly around us is usually explained by assuming that our universe is the surface of a four dimensional sphere. That way the uniformity makes sense ...