Astronomers combine mathematical models with observations sicuro develop workable theories of how the Universe came sicuro be

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The mathematical underpinnings of the Big Bang theory include Albert Einstein’s general theory of relativity along with norma theories of fundamental particles. Today NASA spacecraft such as the Hubble Space Telescope and the Spitzer Space Telescope continue measuring the expansion of the Universe. One of the goals has long been preciso decide whether the Universe will expand forever, or whether it will someday fermo, turn around, and collapse per verso “Big Crunch?”

Retroterra Radiation

According esatto the theories of physics, if we were esatto look at the Universe one second after the Big Bang, what we would see is per 10-billion degree sea of neutrons, protons, electrons, anti-electrons (positrons), photons, and neutrinos. Then, as time went on, we would see the Universe cool, the neutrons either decaying into protons and electrons or combining with protons esatto make deuterium (an isotope of hydrogen). As it continued sicuro cool, it would eventually reach the temperature where electrons combined with nuclei to form neutral atoms. Before this “recombination” occurred, the Universe would have been opaque because the free electrons would have caused light (photons) to scatter the way sunlight scatters from the chicchera droplets mediante clouds. But when the free electrons were absorbed to form neutral atoms, the Universe suddenly became transparent. Those same photons – the afterglow of the Big Bang known as cosmic background radiation – can be observed today.

Missions Study Cosmic Background Radiation

NASA has launched two missions sicuro study the cosmic background radiation, taking “infantile pictures” of the Universe only 400,000 years after it was born. The first of these was the Cosmic Background Explorer (COBE). Con 1992, the COBE gruppo announced that they had mapped the primordial hot and cold spots durante cosmic preparazione radiation. These spots are related esatto the gravitational field in the early Universe and form the seeds of the giant clusters of galaxies that stretch hundreds of millions of light years across the Universe. This work earned NASA’s Dr. John C. Mather and George iraniansinglesconnection prova gratuita F. Smoot of the University of California the 2006 Nobel Prize for Physics.

The second mission sicuro examine the cosmic preparazione radiation was the Wilkinson Microware Anisotropy Probe (WMAP). With greatly improved resolution compared to COBE, WMAP surveyed the entire sky, measuring temperature differences of the microwave radiation that is nearly uniformly distributed across the Universe. The picture shows verso map of the sky, with hot regions mediante red and cooler regions con blue. By combining this evidence with theoretical models of the Universe, scientists have concluded that the Universe is “flat,” meaning that, on cosmological scales, the geometry of space satisfies the rules of Euclidean geometry (anche.g., parallel lines never meet, the ratio of circle circumference preciso diameter is pi, etc).

A third mission, Planck, led by the European Space Agency with significant participation from NASA, was. launched sopra 2009. Planck is making the most accurate maps of the microwave sostrato radiation yet. With instruments sensitive to temperature variations of a few millionths of per degree, and mapping the full sky over 9 wavelength bands, it measures the fluctuations of the temperature of the CMB with an accuracy attrezzi by fundamental astrophysical limits.


One problem that arose from the original COBE results, and that persists with the higher-resolution WMAP giorno, was that the Universe was too homogeneous. How could pieces of the Universe that had never been per contact with each other have come to equilibrium at the very same temperature? This and other cosmological problems could be solved, however, if there had been a very short period immediately after the Big Bang where the Universe experienced an incredible burst of expansion called “inflation.” For this inflation esatto have taken place, the Universe at the time of the Big Bang must have been filled with an unstable form of energy whose nature is not yet known. Whatever its nature, the inflationary model predicts that this primordial energy would have been unevenly distributed per space paio sicuro per kind of quantum noise that arose when the Universe was extremely small. This pattern would have been transferred esatto the matter of the Universe and would spettacolo up durante the photons that began streaming away freely at the moment of recombination. As verso result, we would expect esatto see, and do see, this kind of pattern in the COBE and WMAP pictures of the Universe.

But all this leaves unanswered the question of what powered inflation. One difficulty per answering this question is that inflation was over well before recombination, and so the opacity of the Universe before recombination is, durante effect, per curtain drawn over those interesting very early events. Fortunately, there is verso way sicuro observe the Universe that does not involve photons at all. Gravitational waves, the only known form of information that can reach us undistorted from the instant of the Big Bang, can carry information that we can get per niente other way. Several missions are being considered by NASA and ESA that will aspetto for the gravitational waves from the epoch of inflation.

Dark Energy

During the years following Hubble and COBE, the picture of the Big Bang gradually became clearer. But in 1996, observations of very distant superatic change con the picture. It had always been assumed that the matter of the Universe would slow its rate of expansion. Mass creates gravity, gravity creates pull, the pulling must slow the expansion. But supernovae observations showed that the expansion of the Universe, rather than slowing, is accelerating. Something, not like matter and not like ordinary energy, is pushing the galaxies apart. This “stuff” has been dubbed dark energy, but puro give it verso name is not onesto understand it. Whether dark energy is a type of dynamical fluid, heretofore unknown sicuro physics, or whether it is a property of the vacuum of empty space, or whether it is some modification sicuro general relativity is not yet known.

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