Universe in the very first moments after the big bang.Īs a result, the observable universe we see today Inflation which caused an accelerated expansion of the The theory positsĪ new form of energy, carried by a field dubbed the ![]() Triggering the primordial sound waves and the seeds Problem and also provides a physical mechanism for (Bryan Christie Design)įortunately, the theory of inflation solves the horizon Reionized most of the hydrogen and helium. During the recombination periodĪbout 380,000 years later, the first atoms formed and theĬosmic microwave background (CMB) radiation was emitted.Īfter another 300 million years, radiation from the first stars The region that a hypothetical viewer after inflation would seeĪs the universe expands). This dilemma is known as the horizon problem.Īs inflation expanded the universe, the plasma of photonsĪnd charged particles grew far beyond the horizon (the edge of Therefore, no physical process that obeys causalityĬan explain the structure's origin. The horizon eventually becomes smaller than the The origin of structures of a particular physical size, The horizon defines the sphere of influence of any Grows until it reaches the radius of the observable universe today.īecause information cannot be conveyed faster than light, CosmologistsĬall the edge of this region the horizon, the placeīeyond which you cannot see. Only a finite region of the universe that encompasses theĭistance light has traveled since the big bang. Imagine yourself as an observer witnessing the big bangĪnd the subsequent expansion. That triggered the sound waves? The question is troubling. Yet what was the prime mover, the source of the initial disturbances The right amplitude to form the large-scale structures we see today. In fact, the one-in-100,000 variations observed in the CMB are of exactly Under theĪttractive influence of gravity, the denser areas coalesced into stars and galaxies. Pressure that had resisted the contraction of dense clumps. At the same time, matter was freed of the radiation Rarefied regions, so the pattern of hot and cold spots induced by the sound waves Photons releasedįrom hotter, denser areas were more energetic than photons emitted from ![]() The photons were no longer scattered by collisions with charged particles, soįor the first time they traveled largely unimpeded through space. This transition, called recombination, changed the situation dramatically. Of the gas decreased enough for the protons to capture the electrons and becomeĪtoms. Size - about 380,000 years after the big bang &mdash the temperature ![]() When distances in the universe grew to one thousandth of their current But the results suggest that the biggest component of the modern cosmos is a mysterious entity called dark energy. Inflation, the rapid expansion of the universe in the first moments after the big bang, triggered sound waves that alternately compressed and rarefied regions of the primordial plasma.Īfter the universe had cooled enough to allow the formation of neutral atoms, the pattern of density variations caused by the sound waves was frozen into the cosmic microwave background (CMB) radiation.īy studying the acoustic signals in the CMB, cosmologists have estimated the age, composition and geometry of the universe.
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