Questions tagged [universe]
Questions regarding all of time and space and its contents.
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What is in the center of the universe?
If the universe has formed & originated by a Big Bang Explosion, then there must be empty space left in the center of the explosion site, as all the matter is travelling at tremendous speeds away ...
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How can the universe be infinite?
I've heard from renowned astrophysicists that we don't yet know whether or not the Universe is infinite. How is that possible regarding the big bang theory is accepted (as they all do)? Are they ...
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Will we start seeing galaxies disappear due to Universe expansion? [duplicate]
Does the fact that universe is currently expanding at an accelerating rate means that far far away objects (FAO) might start disappearing with time, set aside the "red shift"?
I'm saying this ...
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What exactly is the "paradox" in Olber's Paradox?
To the extent of my understanding, Olber’s paradox states that if the universe was static and homogeneous, we should see a star at every point in the night sky and therefore the night sky should be ...
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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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Are there ways to estimate size of the "whole universe"?
Words escape me, but by "whole universe" (I think) I mean everything that's spatially connected to the observable universe in a conventional sense. If there is a better term for it, please let me know!...
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How can the 13.8 billion years old universe have a radius of 46 billion light years? [duplicate]
The universe is about 13.8 billion years old. Assume at the big-bang it starts from a small region and the maximum possible speed according Einstein is the speed of light how can the universe got a ...
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Is our universe included inside a black hole? [duplicate]
This question repetitively comes to my mind but I've never found any good scientist article to argue about it, only esoteric or speculative web articles without much valuable background.
So let's ...
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Does the universe have an edge?
I've heard the universe is just an empty cavity. Does the universe have any edge or stop or is it just an infinite empty cavity?
user73898
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Does the Milky Way move through space?
Does our galaxy moves through space? Or does it stay in a single location? If it does move, what causes it to move?
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When the universe expands does it create new space, matter, or something else?
I am wondering what exactly is meant when it is said the universe expands. Does it simply create new space for matter to fill, does it also create new matter/dark matter to fill that space, or am I ...
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What is the physical, geometric shape of the universe?
I'm not asking about theoretical ball, vs saddle, vs flat surface which is just a metaphor with 2D space.
It's hard to say as we see very little of it, and we see them in the past because light ...
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How can 'HD 140283' be older than the universe?
Scientists have known about the star HD 140283, informally nicknamed the Methuselah star, for more than 100 years, since it cruises across the sky at a relatively rapid clip. The star moves at about ...
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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 do we know we're not getting bigger?
Alright so I've been thinking a lot about how the universe expands and I've always wondered if we're getting bigger as well. Since everything would be getting larger at an equal rate (tools of ...
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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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Is the whole universe is rotating on an axis?
Most of the celestial bodies we know are rotating or spinning on its axis.Is there any chance for the universe to rotate on its axis?
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How can the universe be expanding faster than speed of light? [duplicate]
So the story goes like this:
A long time ago, 13.799±0.021 billion years to be exact, something happened. It was a big bang, loud explosion and universe came to existence. It grew and grew, and now ...
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What was "space" like before big bang?
I have a simple question which I think about often but have no answer.
If The Big Bang is true, than if the whole space was just a point 14 billion years ago, then what was around that point, some ...
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Does the recent news of "ten times more galaxies" imply that there is correspondingly less dark matter?
Nature: Universe has ten times more galaxies than researchers thought
NASA feature: Hubble Reveals Observable Universe Contains 10 Times More Galaxies Than Previously Thought
Headlines sometimes ...
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On what scale does the universe expand?
According to the theory (or my understanding of it), the universe is not only expanding, but speeding up.
If the galaxies are moving apart, are the solar systems within them also moving apart from ...
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Observable universe equals its Schwarzschild radius (event horizon)?
The estimated age of the universe is 14 billion years.
The estimated Schwarzschild radius (event horizon) of the observable universe is 14 billion light-years.
What are the ramifications?
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How does light affect the universe?
When light is emitted by for example a star, that star loses energy - which causes it to reduce its gravity. Then that energy begins a journey for potentially billions of years, until it reaches some ...
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Outside of a Universe and its origin
Per the Big Bang Theory, the universe was formed from a dense singular point which existed 13 billion years ago and has been expanding ever since. This suggests that the point should have existed ...
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Is the universe expanding faster than speed of light?
The celestial bodies like stars and galaxies are moving away from each other. How fast are they moving apart? Is that speed more than the speed of light?
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Latest cosmological parameters
I'm looking for the latest values (with uncertainties) of the four main cosmological density parameters $\Omega_i$ :
\begin{align}\tag{1}
\Omega_{\text{mat}} &={} ?,
&\Omega_{\text{rad}} &=...
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What explains the existence of energy/matter if it cannot be created or destroyed?
If the energy/matter that was contained in the singularity before the Big Bang had always existed, and if it’s true that energy/matter cannot be created or destroyed, then what explains its existence?
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What's the fastest moving object in the universe?
We know that nothing can have proper velocities larger than the speed of light in vacuum. But are there any objects in space that get close to it? Any comets, or other objects thrown by gravity or ...
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Are there any alternative explanations for the gravitational force we attribute to dark matter?
It always seemed counter-intuitive to me that we observed an measured a gravitational force and since the universe has not enough mass to account for it, the conclusion was to say there's a different ...
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Do parallel universes exist?
Do other universes like ours exist?
If they exist, how do we know that they exist when we have even not seen the ends of our own universe?
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Does the CMB pattern evolve in a human lifetime?
I was thinking, as CMB is a snapshot of a slice of the Universe during recombination, how much the cmb is changing with time ?
I mean as we progress in time we look a CMB a bit more faraway each time, ...
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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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Relation between black hole mass and radius, and our universe's [duplicate]
Is there a graph of known black holes, with their estimated mass in the X axis and their estimated radius in the Y axis? If so, where can we find it? I would like to know if a black whole with the ...
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Can there be an infinity of stars in the Universe? [duplicate]
I have a mind puzzle.
Can there be an infinity of stars in the Universe ?
I have 2 opposed reasonings, yet I don’t find any flaw in them. Can you help me here ?
Answer A : No, the number of stars ...
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How can redshifted light be detected?
I've been reading about redshifts and it got me really curious. Basically, I want to figure out how we know light is redshifted and what's the original emitted light.
I found the following question ...
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Age of the universe
A Galactic year is estimated to be around 250 million "terrestrial" years. That means there will be about 4 rotations per billion years. And age of the universe is estimated to be near 13.8 billion "...
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Are there any sounds in space?
Is our universe noisy or silent? Can people hear them? When astronauts are out of the Earth and near an explosion, can they hear its noise.
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What is the shape of Universe?
What we can assume by the shape of universe. As I know when we talk about universe we talk about multi dimension structure but that structure should have some shape. I wonder that if we look the ...
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What is the volume of the universe?
Of course it is not exactly known how big the universe is, but I thougt that the universe is about 100 billion lightyears in diameter. But if that is true can you also make an estimation of the volume ...
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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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Why is there a difference between the cosmic event horizon and the age of the universe?
According to wiki the cosmic event horizon is 5 Gpc but the age of the universe is about 13,7 billion years. Usually light from far galaxys needed at most 13,7 billion years to reach the earth so the ...
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Can the theory of multiverse explain dark matter?
If there are many universes, they must have a gravity effect on each other. Since dark matter is measured through gravity, but we don't know the mass behind it, isn't it possible that it comes from ...
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Amount of black holes over time
Hello the number of black holes is much bigger than the number of black holes in the past right?Let $b$ be the number of black holes in the universe.Obviously $\frac{db}{dt}>0$ but what about $\...
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Is there any practical use for astronomy?
Although astronomy is very cool and the things we are learning are awesome, is there really any practical use to knowing the things we know about the universe?
Do other fields of science draw from ...
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How many sun-like stars are there in the universe?
After yesterday's announcement of the Kepler telescope finding a huge amount of newly observed exoplanets, i saw a headline claiming that as much as 22% of sun like stars in the universe have planets ...
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Can there be planets, stars and galaxies made of dark matter or antimatter?
We know that the universe has more dark and anti matter as compared to normal matter. Can there be dark matter galaxies or antimatter galaxies?
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Why black holes are extremely cold?
"The most massive black holes in the Universe, the supermassive black
holes with millions of times the math [sic] of the Sun will have a
temperature of 1.4 x $10^{-14}$ Kelvin. That's low. Almost ...
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Does the mass of the observable universe ever change?
First do we have anyway to even estimate the mass of the entire observable universe? And then is there any data that shows mass being gained or lost? Would we ever know if someone was playing with ...
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