The big bang theory is the most widely accepted cosmological explanation of how the universe formed. According to the theory of inflation, the early universe expanded exponentially fast for a fraction of a second after the big bang. Thomson about the thermal death of the universe over time, the nuclear fuel of the stars will. Today, the principles at the heart of inflation theory have a profound impact. As dark energy causes the universe to expand everfaster, it may spur some very distant galaxies to apparently move faster than the speed of light. The observed hubble expansion of the universe together with the discovery of the cosmic.
It was developed around 1980 to explain several puzzles with the standard big bang theory, in which the universe expands relatively gradually throughout its history. Cosmology is the scientific study of the large scale properties of the universe as a whole. Cosmic inflation, the beginning of the universe, and the. The very early universe likely underwent a period of enormous expansion called inflation. The best current theory, the inflationary universe model assumes that all of space is filled with an extremely concentrated, unstable form of energy that will be transformed into particles of matter at the instant of the big bang. In trying to understand the universe, two major problems remained. Popular science books written by astrophysicists, astrophysics textbooks and to some extent professional astronomical literature addressing the expansion of the universe, 1.
The inflationary universe theory was invented to overcome these problems. But no one knows how space and time came into existence in the first place. Mystery of universes expansion rate widens with new. Inflationary universe theory the inflationary universe theory proposes a brief period of extremely rapid accelerating expansion in the very early universe, before the radiation dominated era called the hot big bang. This theory rests upon four strong pillars, a theoretical framework based on general relativity, as put forward by albert einstein 1 and alexander a. It solved knotty problems of universal structure, but it. The bestsupported theory of our universe s origin centers on an event known as the big bang. The expansion of the universe nucleosynthesis of the light elements origin of the cosmic background radiation formation of galaxies and largescale structure the big bang model makes accurate and scientifically testable hypotheses in each of these.
It states that at some moment all of space was contained in a single point of very highdensity and hightemperature state from which the universe has been expanding in all directions ever since modern measurements place this moment at approximately. The big bang model is supported by a number of important observations the expansion of the universe the observation that galaxies are receding from us the abundance of the light elements h, he, li these elements were fused from protons and neutrons in the first few minutes after the big bang. This acceleration is believed to be driven by a quantum field in effect, some exotic kind of matter with a repulsive gravitational effect. Evidence for cosmic inflation theory bites the space. In fact, expansion or collapse deflation seemed an almost inevitable result of his original field equations. Inflationary universe models generate many different final perturbation spectra. Then again, maybe it shouldnt be called normal matter since it is a small fraction of the universe.
On the expansion of the universe albert einstein 18791955 predicted a general expansion of the universe from his general theory of relativity. Alan guth why is an inflationary universe so astounding. It endeavors to use the scientific method to understand the origin, evolution and ultimate fate of the entire universe. Mystery of universe s expansion rate widens with new hubble data nasa. At th e en d of th e exponential expansion inflation th e energy of th e unstable vacuum of a. The equations that describe the period of inflation have a very attractive feature. While the concept of dark energy in modern cosmological theory also accelerates the expansion of the universe. If we start at the present and go back into the past, the universe is contracting, getting smaller and smaller.
The expansion of the universe why we use the word expansion. In this approach, the driving mechanism is the inflaton field or inflaton particle. Inflation and quantum cosmology discusses the inflationary universe scenario, including the problems of the standard big bang theory and the interplay between elementaryparticle theory and cosmology. This explosion, according to the big bang theory, spawned the universe. Steinhardt and abraham loeb cosmology goes the universe. When this period of inflation ended, the universe would have continued to expand at the more mellow pace of the original big bang theory but. In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the early universe. Download pdf the inflationary universe free online new. Inflation and the new era of highprecision cosmology. Many other cosmologies have been advanced in the past, of course, in attempts to handle contradictions within the bbt. The inflationary universe theory, on the other hand, is a description of the bang itself, and provides plausible answers to these questions and more. The four key observational successes of the model are.
Dark energy, dark matter science mission directorate. The expanding universe and hubbles law the big bang and. For a general rise in the price level, see inflation. Stars, galaxies, and the universe the expanding universe. If confirmed, the undulating gravitational waves would amount to nearproof of the big bang theory known as inflation, and their magnitude would reveal exactly how energetically the universe inflated. A ccording to th e inflationary universe scen ario th e universe in th e very early stages of its evolution was exponentially ex p an d in g in th e unstable vacuum like state. The inflation theory proposes a period of extremely rapid exponential expansion of the universe during its first few moments. Inflation theory brings together ideas from quantum physics and particle physics to explore the early moments of the universe, following the big bang. According to inflation theory, the universe was created in an unstable energy state, which forced a rapid expansion of the universe in its early moments. This theory was developed in 1948 by fred hoyle 19152001, herman bondi 19192005 and thomas gold 19202004 as an alternative to the big bang to explain the origin and expansion of the universe.
Even though the universe always evolves away from flatness at all other periods in the history of the universe, during the inflationary period the universe is actually driven towards flatness incredibly quickly. The results suggest that a signal seen by the bicep2 collaboration, purported to be evidence of inflation in the early universe. According to their theory, the history of our existence began billions of years ago with a now absent field that propelled the universe into a phase of rapid expansion called inflation. However, this hasnt always been the case and for a while the steady state theory was very popular. Instead we think of space itself as expanding kind of like with the balloon analogy. Taking stock of the big bang theory of inflation quanta. What do astronomers predict about the future of the universe. Astronomers using nasa s hubble space telescope say they have crossed an important threshold in revealing a discrepancy between the two key techniques for measuring the universe s expansion rate. The universe, big bang theory, dark energy, gravitational. The local laws of physics and chemistry can differ from one pocket universe to another, which together would form a multiverse. Pop the latest astrophysical measurements, combined with theoretical problems, cast doubt on the longcherished inflationary theory of the early cosmos and suggest we need new ideas by anna ijjas, paul j.
Fred hoyle 19152001 fred hoyle is actually the one who coined the term big bang. Astronomers theorize that billions of years ago, the universe was no larger than the period at the end of this sentence. In the steady state universe theory, the universe is expanding but is also eternally unchanging. Hundreds of them appear in unified theories of physics, such as string theory. Cosmologists introduced this idea in 1981 to solve several important problems in cosmology. According to the big bang theory, the total number of photons in the universe practically did not change during its evolution, but the energy of each photon decreased as the temperature of the universe t. The cosmic inflation hypothesis, its relation to fundamental theory on the beginning of the universe, and the light that both shed on how the various elements and. In the context of einsteins theory of general relativity, we tend not to think of objects as moving through space as they recede from one another. In the chaotic primeval universe, there was sure to be some patch of space where one of these fields met the conditions for inflation.
The usual theory of eternal inflation predicts that globally our universe is like an infinite fractal, with a mosaic of different pocket universes, separated by an inflating ocean, hawking explained. Recent research work suggest that the whole universe is expanding in an accelerated frame. Inflation model and inflation theory redirect here. First, the expansion of the universe, discovered by edwin p. The friedmann equations university of north carolina at. The steady state theory of hoyle 3, for example, was an attempt to rescue the bbt from its. The hot big bang theory is one of the most remarkable successes of modern science. The theory of inflation modifies our understanding of just the first tiny fraction of a second of the history of the universe, and then the description merges with that of the standard big bang theory, preserving all the successes of the older theory.
According to the big bang theory, the universe began about. The big bang theory is the prevailing cosmological model for the birth of the universe. The physics of the universe the big bang and the big crunch the expanding universe and hubbles law main topics introduction main topics intro the big bang and the big crunch special and general relativity black holes and wormholes quantum theory and. Assume, for a moment, the universe is not expanding. Being a quantum theory, there is a field interpretation of inflation theory. Since the expansion of the universe is the basis of the big bang model, these misunderstandings are fundamental. This is because new galaxies are formed in the empty space that is created by the expansion. Stars, galaxies, and the universe the expanding universe key concepts what is the big bang theory. Inflationary theory gets around this flatness problem because inflation changes the way the geometry of the universe evolves with time. Guth has researched elementary particle theory and how particle. Inflation and the new era of highprecision cosmology mit. The standard classical description of the universe becomes possible at the planck time, when the temperature of the. T h e in flation ary u n iverse stanford university. The rest everything on earth, everything ever observed with all of our instruments, all normal matter adds up to less than 5% of the universe.
Wmap inflation theory wilkinson microwave anisotropy probe. This theory was born of the observation that other. Steady state ss was an alternative theory develpoed in 1948 by hoyle, gold, and bondi ss claimed that new matter was continuously being created as the universe expanded to keep the average density of matter equal over time discovered in 1964 by radio astronomers arno penzias and robert wilson. The discovery ten years ago that the expansion of the universe is accelerating put in place the last major building block of the present cosmological model, in which the universe is composed of 4% baryons, 20% dark matter, and 76% dark energy. Evidence for cosmic inflation theory bites the space dust. In the original version of the inflationary theory guth 1981, the state that drove the. The inflation debate princeton physics princeton university. To solve these, the big bang theory is modified by the inflation theory, which states that the universe expanded rapidly shortly after it was created. Stephen hawkings final theory about our universe has just.
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