All told, there are six different eras we can break the Universe into, and we're already in the final one. How matter top , radiation middle , and a cosmological constant bottom all evolve with time in an expanding Universe. As the Universe expands, the matter density dilutes, but the radiation also becomes cooler as its wavelengths get stretched to longer, less energetic states.
Dark energy's density, on the other hand, will truly remain constant if it behaves as is currently thought: as a form of energy intrinsic to space itself. The reason for this can be understood from the graph above. Everything that exists in our Universe has a certain amount of energy in it: matter, radiation, dark energy, etc.
As the Universe expands, the volume that these forms of energy occupy changes, and each one will have its energy density evolve differently. In particular, if we define the observable horizon by the variable a , then:. A visual history of the expanding Universe includes the hot, dense state known as the Big Bang and the growth and formation of structure subsequently. The full suite of data, including the observations of the light elements and the cosmic microwave background, leaves only the Big Bang as a valid explanation for all we see.
As the Universe expands, it also cools, enabling ions, neutral atoms, and eventually molecules, gas clouds, stars, and finally galaxies to form. A Universe that has been around longer, therefore, will have expanded more.
It will be cooler in the future and was hotter in the past; it was gravitationally more uniform in the past and is clumpier now; it was smaller in the past and will be much, much larger in the future. By applying the laws of physics to the Universe, and comparing the possible solutions with the observations and measurements we've obtained, we can determine both where we came from and where we're headed.
We can extrapolate our past history all the way back to the beginning of the hot Big Bang and even before, to a period of cosmic inflation. We can extrapolate our current Universe into the far distant future as well, and foresee the ultimate fate that awaits everything that exists. Our entire cosmic history is theoretically well-understood, but only because we understand the theory of gravitation that underlies it, and because we know the Universe's present expansion rate and energy composition.
Light will always continue to propagate through this expanding Universe, and we will continue to receive that light arbitrarily far into the future, but it will be limited in time as far as what reaches us. We will need to probe to fainter brightnesses and longer wavelengths to continue to see the objects presently visible, but those are technological, not physical, limitations. When we draw the dividing lines based on how the Universe behaves, we find that there are six different eras that will come to pass.
We already entered this final era billions of years ago. Fluctuations in spacetime itself at the quantum scale get stretched across the Universe during inflation, giving rise to imperfections in both density and gravitational waves.
Whether inflation arose from an eventual singularity or not is unknown, but the signatures of whether it occurred are accessible in our observable Universe. Inflationary era. Prior to the hot Big Bang, the Universe wasn't filled with matter, antimatter, dark matter or radiation. It wasn't filled with particles of any type. Instead, it was filled with a form of energy inherent to space itself: a form of energy that caused the Universe to expand both extremely rapidly and relentlessly, in an exponential fashion.
And then, abruptly, some All of that energy, once inherent to space itself, got converted into particles, antiparticles, and radiation. With this transition, the inflationary era ended, and the hot Big Bang began. At the high temperatures achieved in the very young Universe, not only can particles and photons be spontaneously created, given enough energy, but also antiparticles and unstable particles as well, resulting in a primordial particle-and-antiparticle soup.
Time one discover how the universe began
Yet even with these conditions, only a few specific states, or particles, can emerge. Primordial Soup era. Once the expanding Universe is filled with matter, antimatter and radiation, it's going to cool. Whenever particles collide, they'll produce whatever particle-antiparticle pairs are allowed by the laws of physics.
As the Universe cools, the energy drops, and it becomes harder and harder to create more massive particle-antiparticle pairs, but annihilations and other particle reactions continue unabated. And after some radioactive decays and a few final nuclear reactions, all we have left is a hot but cooling ionized plasma consisting of photons, neutrinos, atomic nuclei and electrons. At early times left , photons scatter off of electrons and are high-enough in energy to knock any atoms back into an ionized state.
An unknown error has occurred.
The Universe is accelerating
Please click the button below to reload the page. If the problem persists, please try again in a little while. Read preview. Murphey, associate editor Those in the business of understanding things must come to grips with them in the context of their particular specialty. Krieger Indiana University Press, Read preview Overview. Jeans University Press, Perspectives on Science and Christian Faith, Vol.
Heisenberg, Werner The Columbia Encyclopedia, 6th ed. Bachelard, Gaston The Columbia Encyclopedia, 6th ed. Modern observations of accelerating expansion imply that more and more of the currently visible universe will pass beyond our event horizon and out of contact with us.
Beginning of the Universe - Steady State Theory Proved False
The eventual result is not known. This theory suggests that only gravitationally bound systems, such as galaxies, will remain together, and they too will be subject to heat death as the universe expands and cools. Other explanations of dark energy, called phantom energy theories, suggest that ultimately galaxy clusters, stars, planets, atoms, nuclei, and matter itself will be torn apart by the ever-increasing expansion in a so-called Big Rip. The Big Bang as the origin of the universe: One of the common misconceptions about the Big Bang model is that it fully explains the origin of the universe.police-risk-management.com/order/untraceable/wuga-recuperare-cronologia-messaggi.php
Big Bang Theory
However, the Big Bang model does not describe how energy, time, and space was caused, but rather it describes the emergence of the present universe from an ultra-dense and high-temperature initial state. The Big Bang was "small" : It is misleading to visualize the Big Bang by comparing its size to everyday objects. When the size of the universe at Big Bang is described, it refers to the size of the observable universe, and not the entire universe. Hubble's law violates the special theory of relativity : Hubble's law predicts that galaxies that are beyond Hubble distance recede faster than the speed of light.
However, special relativity does not apply beyond motion through space. Hubble's law describes velocity that results from expansion of space, rather than through space. Doppler redshift vs cosmological redshift : Astronomers often refer to the cosmological redshift as a Doppler shift which can lead to a misconception. Accurate derivation of the cosmological redshift requires the use of general relativity, and while a treatment using simpler Doppler effect arguments gives nearly identical results for nearby galaxies, interpreting the redshift of more distant galaxies as due to the simplest Doppler redshift treatments can cause confusion.
The Big Bang explains the evolution of the universe from a density and temperature that is well-beyond humanity's capability to replicate, so extrapolations to most extreme conditions and earliest times are necessarily more speculative. How the initial state of the universe originated is still an open question, but the Big Bang model does constrain some of its characteristics. For example, observations indicate the universe is consistent with being flat which implies a balance between gravitational potential energy and other forms requiring no additional energy to be created,   while quantum fluctuations in the early universe can provide the circumstances for dense regions of matter such as superclusters to form.
Ultimately, the Big Bang theory, built upon the equations of classical general relativity, indicates a singularity at the origin of cosmic time, and such an infinite energy density may be a physical impossibility. In any case, the physical theories of general relativity and quantum mechanics as currently realized are not applicable before the Planck Epoch , and correcting this will require the development of a correct treatment of quantum gravity. While it is not known what could have preceded the hot dense state of the early universe or how and why it originated, or even whether such questions are sensible, speculation abounds as the subject of " cosmogony ".
Proposals in the last two categories see the Big Bang as an event in either a much larger and older universe or in a multiverse. As a description of the origin of the universe, the Big Bang has significant bearing on religion and philosophy. From Wikipedia, the free encyclopedia. The prevailing cosmological model for the observable universe. Early universe. Subject history. Discovery of cosmic microwave background radiation.
History of the Big Bang theory - Wikipedia
Religious interpretations of the Big Bang theory. Main article: Chronology of the universe. See also: Gravitational singularity and Planck epoch. Main articles: Cosmic inflation and baryogenesis. Main articles: Big Bang nucleosynthesis and cosmic microwave background radiation. Main article: Structure formation. Main article: Accelerating expansion of the universe. Main article: List of cosmological horizons. Main article: History of the Big Bang theory. See also: Timeline of cosmological theories. XDF size compared to the size of the Moon XDF is the small box to the left of, and nearly below, the Moon — several thousand galaxies , each consisting of billions of stars , are in this small view.
XDF view — each light speck is a galaxy — some of these are as old as XDF image shows fully mature galaxies in the foreground plane — nearly mature galaxies from 5 to 9 billion years ago — protogalaxies , blazing with young stars , beyond 9 billion years. Main articles: Hubble's law and Metric expansion of space. See also: Distance measures cosmology and Scale factor universe.
- The Structure and Evolution of the Universe.
- A Whisper of the Romantic in the Eye of God.
- Diet Digest for Dudes.
- Irene Rice Pereira: Her Paintings and Philosophy (American Studies).
Main article: Cosmic microwave background radiation. Main article: Big Bang nucleosynthesis. Main articles: Galaxy formation and evolution and Structure formation. See also: List of unsolved problems in physics.
Main article: Baryon asymmetry. Main article: Dark energy. Main article: Dark matter. Main article: Ultimate fate of the universe. Main articles: Cosmogony and Problem of why there is anything at all. Main article: Religious interpretations of the Big Bang theory. Physics portal. For some writers, this denotes only the initial singularity, for others the whole history of the universe. Usually, at least the first few minutes during which helium is synthesized are said to occur "during the Big Bang".