Questions tagged [space-time]
Questions regarding the 4-dimensional background structure of our universe.
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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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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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Why is the observable Universe larger than its age would suggest?
The age of the Universe is estimated at 13.8 billion years, and current theory states nothing can exceed the speed of light, which can lead to the incorrect conclusion that the universe can't have a ...
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By putting a mirror in space, would we be able to see into the past?
I only ask this because of how fast light travels. The question remains in the title. Why, or why not, would this work?
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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 ...
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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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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 universe as ...
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How does the concept of a universe with no center work?
I understand basically that the universe is homogenous (looks the same from every point) and I was told in my astro class that it's supposed to have no center, but how that works boggles my mind. I ...
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When we see the Sun, do we actually see its past?
The Sun's rays hit our eyes around 8 minutes after they are emitted from the Sun.
Does this mean that the Sun that we see is always the Sun as it was some 8 minutes before? I strongly think this must ...
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Distinction between metric expansion and objects just moving apart from each other?
I see explanations likes this:
Galaxies and other sources, then, are not strictly expanding away from each other but rather are attached to the fixed grid on the expanding fabric of spacetime. Thus, ...
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Are wormholes even possible?
While this question could fall under Space Exploration or Physics (I don't have the "best" reputation on THAT forum), I feel that it is very much related to how the universe itself functions, ...
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Life planets orbiting black-holes. Can/Do they really exist?
So, I watched Interstellar and if you watched it too you know that there's a planet orbiting a black-hole, they call it Miller's Planet. According to the movie, every hour on Miller's Planet is ...
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Based off of the study that found the universe has a positive curvature, how big would the whole universe be?
This study found that the universe has a positive curvature https://www.nature.com/articles/s41550-019-0906-9. I didn't really want to buy it and see if it says how big the universe might be. I know ...
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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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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 ...
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How could universe inflate itself out of the very dense and curved early spacetime? Could it happen in a black hole too?
Wasn't spacetime as much curved as a black hole directly after Big Bang, because mass was so densly packed? Wasn't everything like an event horizon and how could things expand across it? Could ...
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How long would it take to reach the edge of the reachable universe?
How long would it take to reach the current edge of the reachable portion of the universe, with the following bounds in mind:
We figure out a way build a space ship to provide a constant 1 G ...
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How could we tell if the Universe is infinite? [duplicate]
I've heard from a number of people that the Universe is infinite, and from my perspective, I can't see how this can actually be known, especially given that the Universe started out a finite size and ...
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Beginning of space-time
I have read that the Big Bang created space-time, but how could this be possible? The Big Bang was itself a singularity, and a singularity is a point in space-time where the curvature becomes infinite....
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How does space time differ within a galaxy?
Not the same question but is similar to other marked duplicate.
How much time dilation does the center of a galaxy can exist and sustain human life from our point of view? What would a day equal to ...
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Does seeing a gravitationally lensed/magnified galaxy imply that they could also see us as well?
Does an observer in that galaxy see our galaxy magnified as well?
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When we say a galaxy is 200 million light years away, does this account for the expansion of space in the time it took it's light to reach us?
When we see a distant galaxy, the light we are watching started it's journey millions of years ago. In all that time, space has been expanding, so if the initial distance was A, right now the distance ...
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How do we work out the light travel time on a cosmic scale?
I just read this article in the AUSTRALIAN SKY & TELESCOPE magazine, Nov/Dec 2022 Issue 140, on P16, KEEP YOUR DISTANCE: How far away are the objects we see in the universe? And on P23:
"And ...
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Time dilation on an object circling earth
How would a receiver on Earth hear a radio transmission from an object circling earth at 99% of the speed of light for 24 hours. The transmission from the object circulating would be non-stop.
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Light or neutrinos graze or pass through the Sun and arrive at Earth - need an expression for Sun's gravitational effect on observation direction/time
Skyfield's Github has discussion Jupiter hiccup #815 which then links back to to Non-physical gravitational deflection corrections for Solar System bodies #734.
The script and plot from #815 are shown ...
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What effect does time dilation have on bodies orbiting close to Black Holes?
As far as my (somewhat basic) knowledge of astrophysics goes in general the closer to a star your orbit gets smaller (because you travel less distance) and faster (because you're deeper in the gravity ...
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Knowing time any where and any when
My question is if I put you down somewhere in the Milky Way galaxy in any given period of time, is there a way for you to tell when and where you are based on stars or constellations? Or some known ...
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Why does time get slow near a black hole? [closed]
Why exactly does time get slow around a black hole? And does it provide a way to go into the future?
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How does an absolute horizon form before the apparent horizon?
If I understand it correctly, the apparent horizon is the boundary between where light directed outwards will move outwards, and light directed outwards will move inwards. Even if light is moving away ...
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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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How is distance in light-years converted to years back in time?
When I look at the Alnitak,the left most star of Orion's belt, it is 736 light years away. How could I convert this distance to an estimate of how long ago what I am seeing happened.
Would it be ...
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If an exoplanet transit we are seeing is 13000 light years away, are we seeing a 13000-year-old orbit? [duplicate]
If a star is 13000 light years away, doesn't that mean we are seeing 13000-year-old light? If it does, then does that mean when we discover a planet with dimming star light, we are seeing a planet ...
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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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Do gravitationally bound (e.g. orbiting) objects really resist the expansion of space?
Thinking about the expansion of space, it is commonly explained that gravitationally bound objects (like galaxies and galaxy clusters) will not be affected by the expansion of space (dark energy). I ...
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How do we know that spacetime is fabric? [closed]
I have started learning about astronomy as it amazes and inspires me.
I have a question. What led us to believe that spacetime is fabric? What is the evidence shows this, and is it considered proven?
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Will the "fabric of space time" rip from expansion?
I'm quite familiar with the fabric of space time theory and as I've been quite lonely these past few weeks, I started thinking that since the universe is expanding and since the "fabric" is the ...
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What is the fastest a galaxy or other body has been measured to (or can) travel?
Our solar system travels at an average speed of 515,000 mph and our galaxy at 1.3 million mph through space. What is the fastest moving body in space recorded and the fastest can a black hole or ...
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How can we see stars if they are hundred years of light far from the Earth?
So the right question is, is the light years counted from that second when you look up to the sky? If that so, how can we see the stars from the telescope (which I think it starts when you put your ...
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How does space time differ between galaxies? [duplicate]
Does the gravity wells differ enough between galaxies to have different speeds in space time? How much slower in space time would the biggest galaxy have compared to the Milky Way?
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In relativity why does matter bend spacetime in a downward direction [closed]
A major flaw , I think it is in relativity.
