Geometrically, an open universe has a negative Gaussian curvature, K = -1. One way to visualize this geometry is as the 2D surface of a saddle in 3D space. A closed universe has positive Gaussian curvature, K = +1. A closed universe is readily visualized as a sphere.
Is the universe open or closed?
If the system interacts with the environment, it's considered open. While if it's isolated from the environment, it's considered closed. So if the term "universe" means "all that exists", then by definition there is no environment so it cannot interact with it. I think it's pretty straightforward then to say that it is closed.
Can we distinguish between a flat and a closed universe?
The latest research shows that even the most powerful future experiments (like the SKA) will not be able to distinguish between flat, open and closed universe if the true value of cosmological curvature parameter is smaller than 10 −4.
What is the difference between the observable universe and the entire universe?
Cosmologists distinguish between the observable universe and the entire universe, the former being a ball-shaped portion of the latter that can, in principle, be accessible by astronomical observations.
Is the universe an isolated system or an open system?
The (entire) universe is an isolated system. The observable universe is an open system. There are 3 main types of thermodynamic systems, defined by what the system can exchange with its surroundings:
What is an open universe?
If space has negative curvature, there is insufficient mass to cause the expansion of the universe to stop. In such a case, the universe has no bounds, and will expand forever. This is called an open universe.
What is a closed universe mean?
noun. (in cosmology) a hypothetical expanding universe that contains sufficient matter to reverse the observed expansion through its gravitational contraction.
Are we in a closed or open universe?
The authors reanalyzed a major cosmological data set and concluded that the data favors a closed universe with 99% certainty — even as other evidence suggests the universe is flat.
What is meant by an open a closed and a flat universe?
Once upon a time, when astronomers spoke of the universe as "closed," "open," or "flat," they meant that the density of the universe was either so great that it would eventually recollapse because of gravitational attraction; or that its density was so low that gravity would be insufficient to keep it from expanding ...
How many universes are there?
In a new study, Stanford physicists Andrei Linde and Vitaly Vanchurin have calculated the number of all possible universes, coming up with an answer of 10^10^16.
How many dimensions do we know of?
three dimensionsThe world as we know it has three dimensions of space—length, width and depth—and one dimension of time. But there's the mind-bending possibility that many more dimensions exist out there. According to string theory, one of the leading physics model of the last half century, the universe operates with 10 dimensions.
What are the 3 types of universe?
There are basically three possible shapes to the Universe; a flat Universe (Euclidean or zero curvature), a spherical or closed Universe (positive curvature) or a hyperbolic or open Universe (negative curvature).
Is time Travelling possible?
Yes, time travel is indeed a real thing. But it's not quite what you've probably seen in the movies. Under certain conditions, it is possible to experience time passing at a different rate than 1 second per second. And there are important reasons why we need to understand this real-world form of time travel.
Are there multiple universes?
We currently have no evidence that multiverses exists, and everything we can see suggests there is just one universe — our own.
What will happen if the universe is closed?
Also, if the universe is closed, this theory would predict that once this universe collapses it will spawn another universe in an event similar to the Big Bang after a universal singularity is reached or a repulsive quantum force causes re-expansion.
What is the meaning of a closed universe quizlet?
What is the meaning of a "closed" universe? The universe will someday stop expanding and start to collapse. If the density of the universe is greater than the critical density this means that. the universe is expanding at a rate less than the escape speed of the universe.
Why do we call dark matter dark?
Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not absorb, reflect, or emit electromagnetic radiation (like light) and is, therefore, difficult to detect.
What happens if the cosmological constant is constant?
If the cosmological constant really is constant, the expansion of the universe will accelerate indefinitely.
What happens if the universe is flat?
But if the universe is flat and the density of matter is low -- including visible matter, invisible matter, and ordinary energy (which is equivalent to matter) -- something must provide the missing density. That something is the cosmological constant, or some other form of dark energy. Such invisible energy could propel even a closed universe ...
What does "closed" mean in astronomy?
Illustration by Flavio Robles. O nce upon a time, when astronomers spoke of the universe as "closed," "open," or "flat," they meant that the density of the universe was either so great that it would eventually recollapse because of gravitational attraction; or that its density was so low that gravity would be insufficient to keep it ...
Is the universe flat?
A flat two-dimensional universe would resemble a sheet of paper (on which parallel lines stay parallel). Many independent observations indicate that the universe is in fact flat.
How long do quarks last?
It is remarkable how stable the behavior of these fleeting quarks are, trillions of them appearing every second to sustain the molecular structure of the physical universe, for trillions of years through the life of the universe with only very minor deviation of behavior or definition.
Why does the observable universe have a boundary?
What I mean is that our observable universe has a "boundary" because if something is beyond this "boundary", the light from it has not had time to reach us yet (and may never will ). Aliens living on the "boundary" of our observable universe will have their own definition of "observable universe" and it will not be the same as our definition, because there are things in the universe they can see that we can't, and vice versa.
How does coolant work?
The coolant simply absorbs the radiant heat from cylinders then passes it to the air through the radiator.
How many types of thermodynamic systems are there?
There are 3 main types of thermodynamic systems, defined by what the system can exchange with its surroundings:
What is the infinite continuum field?
It also implies that there is a field in which the universe is embedded in, a field replete with infinite energy, information and in all likelihood, consciousness. This infinite continuum field would also entail the top five infinite dimensional features, and thus sustain the multiverse.
Why is the universe an isolated system?
The entire universe, meaning everything there is, including things we cannot see, is an isolated system because it has no "surroundings"; it's literally everything there is. Obviously, a system cannot exchange energy or matter with "surroundings" that do not exist. Continue Reading.
What is the equivalent circuit of a network?
If the two terminals of the network are then interconnected by an impedance, Z . An equivalent circuit can be formed. This equivalent circuit consists of the same general linear Network and to impedances; Each of which shunts a network terminal two common terminals these two impedances have the value = 1.
How to find the curvature of the universe?
One can experimentally calculate this Ω to determine the curvature two ways. One is to count up all the mass-energy in the universe and take its average density then divide that average by the critical energy density. Data from Wilkinson Microwave Anisotropy Probe (WMAP) as well as the Planck spacecraft give values for the three constituents of all the mass-energy in the universe – normal mass ( baryonic matter and dark matter ), relativistic particles ( photons and neutrinos ), and dark energy or the cosmological constant:
What is curvature in space?
The curvature is a quantity describing how the geometry of a space differs locally from the one of the flat space. The curvature of any locally isotropic space (and hence of a locally isotropic universe) falls into one of the three following cases:
How does mass and energy determine the curvature of spacetime?
General relativity explains that mass and energy bend the curvature of spacetime and is used to determine what curvature the universe has by using a value called the density parameter, represented with Omega ( Ω ). The density parameter is the average density of the universe divided by the critical energy density, that is, the mass energy needed for a universe to be flat. Put another way,
What are distance measures?
See also: Distance measures (cosmology) As stated in the introduction, there are two aspects to consider: its local geometry, which predominantly concerns the curvature of the universe, particularly the observable universe, and. its global geometry, which concerns the topology of the universe as a whole.
What is the shape of the universe?
The shape of the universe, in physical cosmology, is the local and global geometry of the universe. The local features of the geometry of the universe are primarily described by its curvature, whereas the topology of the universe describes general global properties of its shape as of a continuous object. The spatial curvature is related ...
What is the comoving coordinates?
Cosmologists normally work with a given space-like slice of spacetime called the comoving coordinates, the existence of a preferred set of which is possible and widely accepted in present-day physical cosmology. The section of spacetime that can be observed is the backward light cone (all points within the cosmic light horizon, given time to reach a given observer), while the related term Hubble volume can be used to describe either the past light cone or comoving space up to the surface of last scattering. To speak of "the shape of the universe (at a point in time)" is ontologically naive from the point of view of special relativity alone: due to the relativity of simultaneity we cannot speak of different points in space as being "at the same point in time" nor, therefore, of "the shape of the universe at a point in time". However, the comoving coordinates (if well-defined) provide a strict sense to those by using the time since the Big Bang (measured in the reference of CMB) as a distinguished universal time.
How is the local geometry of the universe determined?
The local geometry of the universe is determined by whether the density parameter Ω is greater than, less than, or equal to 1.
How does curvature affect distance?
This can be understood geometrically as the curvature affecting the angular size of objects we see which , in turn, impacts our estimate of their distance. The curvature estimate then comes from comparing the estimated distances between things that are very far and things that are closer. One of the most effective is comparing the typical separation between hot/cold spots on the CMB and the typical separation of galaxies in the relatively nearby universe (this is known as the Baryon Acoustic Oscillation measurement). The separation in either case is viewed as an angular diameter distance.
What does Equation 16 show?
Thanks. Equation 16 shows that in the case of spatial flatness (k=0) the transverse comoving distance equals the line-of-sight comoving distance. But, hmm, which conclusion should I draw?
What is spatial geometry?
The spatial geometry refers to the sum of angles = 180° of a triangle at a certain instant of time. Or assuming the expansion is "frozen". The triangle shall be formed by an object of a known size (from one edge to the other) and the distance between this object and our worldline. Both distances are true, meaning measured with rulers.
How is a triangle formed?
Well, if you have the true size of the object, and that object has some angular size, then a triangle is formed by light rays coming from the edges of the object and meeting in the telescope.
What is the length of the BAO matter clustering today?
According to the authors the length of the BAO matter clustering today is 490 MLJ. With this "today" value and z = 1100 the corresponding length at the time of recombination should be 410000 LJ (?). And I guess this length then is a true length (measured with rulers), as it corresponds to that typical density fluctuation in the CMB, the angular size of which is 1 degree today.
Can space time be curved?
I have in my mind that while assuming spatial flatness the space-time still can be curved if the rate of expansion is not linear (it isn't, as we know).
Do the sizes of galaxies have to be correlated?
For this observation, the more important point is just that the sizes are correlated with one another, not that their absolute sizes are known. A simple way of understanding it is that we know the ratio of the length scale given by the CMB and that given by the distribution of nearby galaxies.
