Nor could clearing the pigeons that had roosted in there, or their mess. If the Big Bang theory is true, how did it lead to all the planets, stars and galaxies we can see today? Thanks to a series of calculations, observations from telescopes on Earth and probes in space, our best explanation is this. Around This expanded at an astonishingly high rate and temperature, doubling in size every seconds, creating space as it rapidly inflated.
Within a tiny fraction of a second gravity and all the other forces were formed. Energy changed into particles of matter and antimatter, which largely destroyed each other. Ironically, it was Hoyle who coined the phrase "Big Bang" during a BBC Radio broadcast in March , which was believed by some to be a pejorative dismissal which Hoyle denied.
Eventually, the observational evidence began to favor Big Bang over Steady State. The discovery and confirmation of the cosmic microwave background radiation in secured the Big Bang as the best theory of the origin and evolution of the universe. From the late 60s to the s, astronomers and cosmologist made an even better case for the Big Bang by resolving theoretical problems it raised. These included papers submitted by Stephen Hawking and other physicists that showed that singularities were an inevitable initial condition of general relativity and a Big Bang model of cosmology.
In , physicist Alan Guth theorized of a period of rapid cosmic expansion aka. The s also saw the rise of Dark Energy as an attempt to resolve outstanding issues in cosmology. In addition to providing an explanation as to the universe's missing mass along with Dark Matter, originally proposed in by Jan Oort , it also provided an explanation as to why the universe is still accelerating, as well as offering a resolution to Einstein's Cosmological Constant.
Significant progress was made thanks to advances in telescopes, satellites, and computer simulations, which have allowed astronomers and cosmologists to see more of the universe and gain a better understanding of its true age. Today, cosmologists have fairly precise and accurate measurements of many of the parameters of the Big Bang model, not to mention the age of the Universe itself.
And it all began with the noted observation that massive stellar objects, many light years distant, were slowly moving away from us. And while we still are not sure how it will all end, we do know that on a cosmological scale, that won't be for a long, LONG time! Explore further.
More from Astronomy and Astrophysics. Use this form if you have come across a typo, inaccuracy or would like to send an edit request for the content on this page. For general inquiries, please use our contact form.
For general feedback, use the public comments section below please adhere to guidelines. Your feedback is important to us. However, we do not guarantee individual replies due to the high volume of messages. Your email address is used only to let the recipient know who sent the email.
Neither your address nor the recipient's address will be used for any other purpose. The information you enter will appear in your e-mail message and is not retained by Phys. You can unsubscribe at any time and we'll never share your details to third parties.
More information Privacy policy. This site uses cookies to assist with navigation, analyse your use of our services, collect data for ads personalisation and provide content from third parties. By using our site, you acknowledge that you have read and understand our Privacy Policy and Terms of Use. The history of the universe starting the with the Big Bang. A billion years after the big bang, hydrogen atoms were mysteriously torn apart into a soup of ions. Credit: grandunificationtheory.
The history of the Universe, from the Big Bang to the current epoch. Credit: bicepkeck. Source: Universe Today.
Citation : What is the Big Bang Theory? This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
For stem cells, bigger doesn't mean better 2 hours ago. Relevant PhysicsForums posts Question about Kuiper belt 59 minutes ago. Level of details in prime focus vs eyepiece images 1 hour ago. Our Beautiful Universe - Photos and Videos 5 hours ago. Temperature of gas in a cluster 16 hours ago. Maximum mass of a neutron star Nov 09, But as the universe cooled, photons no longer packed enough punch to make matter-antimatter pairs.
So like an extreme game of musical chairs, many particles of matter and antimatter paired off and annihilated one another. Somehow, some excess matter survived—and it's now the stuff that people, planets, and galaxies are made of.
Our existence is a clear sign that the laws of nature treat matter and antimatter slightly differently. Researchers have experimentally observed this rule imbalance, called CP violation , in action. Physicists are still trying to figure out exactly how matter won out in the early universe. The nickname for this cosmic object—the Sunflower galaxy—is no coincidence: The arrangement of the spiral arms in the galaxy Messier 63, seen here in an image from the Hubble Space Telescope, recalls the pattern at the center of a sunflower.
Within the universe's first second, it was cool enough for the remaining matter to coalesce into protons and neutrons, the familiar particles that make up atoms' nuclei. And after the first three minutes, the protons and neutrons had assembled into hydrogen and helium nuclei.
By mass, hydrogen was 75 percent of the early universe's matter, and helium was 25 percent. The abundance of helium is a key prediction of big bang theory, and it's been confirmed by scientific observations.
Despite having atomic nuclei, the young universe was still too hot for electrons to settle in around them to form stable atoms. The universe's matter remained an electrically charged fog that was so dense, light had a hard time bouncing its way through. It would take another , years or so for the universe to cool down enough for neutral atoms to form—a pivotal moment called recombination.
The cooler universe made it transparent for the first time, which let the photons rattling around within it finally zip through unimpeded. We still see this primordial afterglow today as cosmic microwave background radiation , which is found throughout the universe.
The radiation is similar to that used to transmit TV signals via antennae. But it is the oldest radiation known and may hold many secrets about the universe's earliest moments. There wasn't a single star in the universe until about million years after the big bang. It took that long for gravity to gather clouds of hydrogen and forge them into stars.
The big bang cosmology makes a different prediction: if galaxies were all formed long ago, distant galaxies should look younger than those nearby because light from them requires a longer time to reach us.
Such galaxies should contain more shortlived stars and more gas out of which future generations of stars will form. The test is simple conceptually, but it took decades for astronomers to develop detectors sensitive enough to study distant galaxies in detail.
When astronomers examine nearby galaxies that are powerful emitters of radio wavelengths, they see, at optical wavelengths, relatively round systems of stars.
Distant radio galaxies, on the other hand, appear to have elongated and sometimes irregular structures. Moreover, in most distant radio galaxies, unlike the ones nearby, the distribution of light tends to be aligned with the pattern of the radio emission.
Likewise, when astronomers study the population of massive, dense clusters of galaxies, they find differences between those that are close and those far away. Distant clusters contain bluish galaxies that show evidence of ongoing star formation.
Similar clusters that are nearby contain reddish galaxies in which active star formation ceased long ago. Observations made with the Hubble Space Telescope confirm that at least some of the enhanced star formation in these younger clusters may be the result of collisions between their member galaxies, a process that is much rarer in the present epoch. So if galaxies are all moving away from one another and are evolving from earlier forms, it seems logical that they were once crowded together in some dense sea of matter and energy.
But what would this radiation signature look like? When the universe was very young and hot, radiation could not travel very far without being absorbed and emitted by some particle. This continuous exchange of energy maintained a state of thermal equilibrium; any particular region was unlikely to be much hotter or cooler than the average.
When matter and energy settle to such a state, the result is a so-called thermal spectrum, where the intensity of radiation at each wavelength is a definite function of the temperature.
Hence, radiation originating in the hot big bang is recognizable by its spectrum. In fact, this thermal cosmic background radiation has been detected. While working on the development of radar in the s, Robert H. Dicke, then at the Massachusetts Institute of Technology, invented the microwave radiometer—a device capable of detecting low levels of radiation.
In the s Bell Laboratories used a radiometer in a telescope that would track the early communications satellites Echo-1 and Telstar.
The engineer who built this instrument found that it was detecting unexpected radiation. Arno A. Penzias and Robert W. Wilson identified the signal as the cosmic background radiation. It is interesting that Penzias and Wilson were led to this idea by the news that Dicke had suggested that one ought to use a radiometer to search for the cosmic background.
Astronomers have studied this radiation in great detail using the Cosmic Background Explorer COBE satellite and a number of rocket-launched, balloon-borne and ground-based experiments. The cosmic background radiation has two distinctive properties. First, it is nearly the same in all directions. As George F. Smoot of Lawrence Berkeley Laboratory and his team discovered in , the variation is just one part per , The interpretation is that the radiation uniformly fills space, as predicted in the big bang cosmology.
Second, the spectrum is very close to that of an object in thermal equilibrium at 2. To be sure, the cosmic background radiation was produced when the universe was far hotter than 2. In the s Richard C. The cosmic background radiation provides direct evidence that the universe did expand from a dense, hot state, for this is the condition needed to produce the radiation. In the dense, hot early universe thermonuclear reactions produced elements heavier than hydrogen, including deuterium, helium and lithium.
It is striking that the computed mix of the light elements agrees with the observed abundances. That is, all evidence indicates that the light elements were produced in the hot, young universe, whereas the heavier elements appeared later, as products of the thermonuclear reactions that power stars.
The theory for the origin of the light elements emerged from the burst of research that followed the end of World War II. George Gamow and graduate student Ralph A. Alpher and Herman also realized that a remnant of the original expansion would still be detectable in the existing universe.
Despite the fact that significant details of this pioneering work were in error, it forged a link between nuclear physics and cosmology. The workers demonstrated that the early universe could be viewed as a type of thermonuclear reactor. As a result, physicists have now precisely calculated the abundances of light elements produced in the big bang and how those quantities have changed because of subsequent events in the interstellar medium and nuclear processes in stars.
Our grasp of the conditions that prevailed in the early universe does not translate into a full understanding of how galaxies formed.
Nevertheless, we do have quite a few pieces of the puzzle. Gravity causes the growth of density fluctuations in the distribution of matter, because it more strongly slows the expansion of denser regions, making them grow still denser. This process is observed in the growth of nearby clusters of galaxies, and the galaxies themselves were probably assembled by the same process on a smaller scale.
The growth of structure in the early universe was prevented by radiation pressure, but that changed when the universe had expanded to about 0.
At that point, the temperature was about 3, kelvins, cool enough to allow the ions and electrons to combine to form neutral hydrogen and helium.
The neutral matter was able to slip through the radiation and to form gas clouds that could collapse to star clusters. Observations show that by the time the universe was one fifth its present size, matter had gathered into gas clouds large enough to be called young galaxies.
0コメント