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When we speak of a critical universe, we're referring to the question of whether the universe is open, flat or closed. This is about space itself being curved, so it's a bit hard to think about. However...
We learned in geometry that the interior angles of triangles equal 180 degrees and that's true -- on flat paper. However, if you image a huge triangle on the Earth, with one of its points at the North Pole, one on the Equator and the Meridian of Greenwich and the third on the Equator at the meridian 90 degrees West (through the Great Lakes of the US), the angles of that triangle would be 270 degrees, since each angle is 90 degrees. This is because the Earth is a sphere (or almost one). You could have the same 270 degree triangle on a balloon.
Now imagine that the triangle was on the INSIDE of the balloon, and the sides, instead of appearing to bulge outward, caved inward. That triangle would have angles of LESS than 180 degrees.
The outer triangle represents a closed universe and the interior one an open one (yes, the balloon is closed, but we're not concerned with the whole balloon, only the part with the triangle on it; another way to say this is to suppose the triangle is on the seat portion of a saddle, which curves up away from it.) The critical condition is called Omega; if Omega is greater than one, the universe is closed; if less than one, open, and if equal to one exactly, flat.
The challenge is that the universe is huge, and from any tract we can measure, appears flat, but that may not be the case with the whole universe.
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∙ 10y ago
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What does dark matter have to do the critical of the universe?
Dark matter is crucial for understanding the critical density of the universe. The presence of dark matter significantly increases the total mass and therefore the gravitational pull of the universe, which affects its overall structure and expansion. Without accounting for dark matter, the observed gravitational effects would not align with the predicted critical density required for a flat universe.
What is critical heat flux and what is its physical significance?
critical heat flux is the heat flux at critical point
What is the term for center of the universe?
The Universe does not have a centre.
How do you control the universe?
No the universe is all matter their is.
What is the lagers thing in the universe?
the universe itself
What does it mean when you say that the universe is below the critical density?
If the universe is ever to stop expanding and start contracting there has to be a certain amount of material (mass). This amount is called the 'critical density'. So far as is known to date the universe does not have sufficient mass to stop expanding, hence it is below the critical density.
What is critical density?
The term critical density refers to the value in which the Universe is at balance. This also refers to the stopping of expansion.
Compare and contrast average density and critical density?
the average density is the total amount of matter in the universe, whereas the critical density is about 10 to the -26th power kg/m cubed (to the third power), the dividing point between a closed or open universe.... :)
What does dark matter have to do the critical of the universe?
Dark matter is crucial for understanding the critical density of the universe. The presence of dark matter significantly increases the total mass and therefore the gravitational pull of the universe, which affects its overall structure and expansion. Without accounting for dark matter, the observed gravitational effects would not align with the predicted critical density required for a flat universe.
How dense is dark matter?
This can be answered in two steps: 1) What is the average density of all gravitational matter in the Universe? It has surprised astrophysicists that this density is extremely close to the "critical" density; above which our Universe eventually collapses in itself, and below which our Universe expands forever. This critical density is about 5 x 10^-30 grams per cubic centimeter. 2) How much of the mass of the Universe is NOT dark matter? What shocked astrophysicists even more was determining that the average density of all luminous matter was only about 20% of the critical density. Thus, about 80% of the measured density of our Universe can be accounted for via stuff that gives off light. The ratio of hydrogen to helium to deuterium in our Universe puts an upper limit on the density of baryonic matter in our Universe. This calculation also shows that the density of baryonic matter can not be more than about 20% of the critical density. These two, completely independent calculations of the amount of luminous and of baryonic matter -- the stuff we understand -- in our Universe have left scientists with little choice but to conclude that 80% of the gravitational mass in our Universe is composed of something we don't understand. And that's why we call it "dark" matter. Since the Universe has a density of 5 x 10^-30 grams per cc, and only 80% of that is dark matter, then the latter's average density is about 4 x 10^-30 grams per cc.
What is the hypothesis that neither the earth or sun occupy any special place in the universe?
The critical realization that Earth is not at the center of the universe is now known as the Copernican Revolution. The idea that neither Earth nor Sun occupy a special place in the universe is known as the "Copernican Principle". This hypothesis is scientifically classified as a "Principle of Mediocrity".
What is the greatest power in the universe?
Many scientists believe that the greatest power in the universe is gravity. It is a fundamental force that governs the motion of planets, stars, galaxies, and even light itself. Gravity plays a critical role in shaping the structure and behavior of our universe.
What is a close universe?
The universe may be: 1) "open", which means it will continue to expand forever but at a decreasing rate. 2) "flat", which means it will eventually stop expanding but never reverse. 3) "closed", which means the universe will expand to a maximum size and then collapse in upon itself in a reversal of the big bang. The total mass-density of the universe determines which scenario will be realized. At a critical mass-density, the universe is flat. Some research has drawn scientists to believe the expansion of universe is actually accelerating. That means that the universe may actually be expanding more and more rapidly, due to a force called "dark energy". The existence of this dark energy would complicate all of the above scenarios.
What is the shape of the universe?
Scientists figured out three general possibilities:1.) CLOSED - The Universe can be like a sphere, thus having a positive curvature. (imagine a ball) Therefore it will be finite in size, but it would have no boundaries. If you would go long enough in one direction you would end up in the same place. In such a Universe, a large enough triangle would have more than 180 degrees and parallell lines would eventually meet. A closed Universe would end up in a 'Big Crunch', meaning that eventually it would stop expanding and due to its own gravity it would shrink back. We live in such a Universe, if its density is greater than a so called critical density.2.) FLAT - The Universe is like a sheet of rubber that can be pulled in every direction forever, thus its space is infinite and would have no boundaries. Triangles add up to 180 degrees and parallel lines remain parallel, just like on a sheet of paper. However, don't get confused in here. I used the analogy of a sheet of paper or rubber, to explain that the geomatrical characteristincs would be the same as of a 2D model. The Universe is obviously not literally flat (we're not some shapeless cartoon characters, right?). Such a Universe is possible, if its density equals the critical density.3.) OPEN - The Universe is saddle-shaped, thus having a negative curvature. Therefore its space would be infinite and it would have no boundaries. It would keep expanding forever at an accelerated rate. Large enough triangles would have less than 180 degrees and paralell lines would move apart if long enough. If the Universe's density is smaller than the critical density, then we are part of such Universe.----Which one would you pick? :-P
What is universe adult franchies what are its merit?
The Universe Adult franchise refers to a series of documentaries made by the History Channel focusing on topics related to ancient civilizations, UFO investigations, and conspiracy theories. The merit of this franchise lies in its ability to entertain and educate viewers on historical mysteries and scientific theories related to the universe and extraterrestrial life. The documentaries often prompt critical thinking and spark curiosity about the unknown aspects of our world.
Is there anything around the universe?
No, there is not there is no edge to the universe, and there is nothing outside of the universe. there just IS the universe.
What the ptolemaic of the universe had in the center of the universe?
This model of the universe placed the Earth at the center of the universe
