Beyond the Cosmos - Netflix

Wed 15 May 2019

Filed under netflix

Tags netflix Documentary English

The world may run on it, but do we actually know what 'time' really is? Travel back to the Big Bang, where physicists believe the ultimate secrets of time may be hidden. Brian Greene is going to let you in on a secret: We've all been deceived. Our perceptions of time and space have led us astray. Much of what we thought we knew about our universe-that the past has already happened and the future is yet to be, that space is just an empty void, that our universe is the only universe that exists-just might be wrong. The Fabric of the Cosmos, a four-hour series based on the book by renowned physicist and acclaimed author Brian Greene, takes us to the frontiers of physics to see how scientists are piecing together the most complete picture yet of space, time and the universe. With each step, audiences will discover that just beneath the surface of our everyday experience lies a world we'd...

Beyond the Cosmos - Netflix

Type: Documentary

Languages: English

Status: Ended

Runtime: 60 minutes

Premier: 2012-04-03

Beyond the Cosmos - Observable universe - Netflix

The observable universe is a spherical region of the Universe comprising all matter that can be observed from Earth at the present time, because electromagnetic radiation from these objects has had time to reach Earth since the beginning of the cosmological expansion. There are at least 2 trillion galaxies in the observable universe. Assuming the universe is isotropic, the distance to the edge of the observable universe is roughly the same in each direction. That is, the observable universe is a spherical volume (a ball) centered on the observer. Every location in the universe has its own observable universe, which may or may not overlap with the one centered on Earth. The word observable in this sense does not refer to the capability of modern technology to detect light or other information from an object, or whether there is anything to be detected. It refers to the physical limit created by the speed of light itself. Because no signals can travel faster than light, any object farther away from us than light could travel in the age of the universe (estimated as of 2015 around 13.799±0.021 billion years) simply cannot be detected, as they have not reached us yet. Sometimes astrophysicists distinguish between the visible universe, which includes only signals emitted since recombination—and the observable universe, which includes signals since the beginning of the cosmological expansion (the Big Bang in traditional physical cosmology, the end of the inflationary epoch in modern cosmology). According to calculations, the current comoving distance—proper distance, which takes into account that the universe has expanded since the light was emitted—to particles from which the cosmic microwave background radiation (CMBR) was emitted, which represent the radius of the visible universe, is about 14.0 billion parsecs (about 45.7 billion light-years), while the comoving distance to the edge of the observable universe is about 14.3 billion parsecs (about 46.6 billion light-years), about 2% larger. The radius of the observable universe is therefore estimated to be about 46.5 billion light-years and its diameter about 28.5 gigaparsecs (93 billion light-years, 8.8×1023 kilometres or 5.5×1023 miles). The total mass of ordinary matter in the universe can be calculated using the critical density and the diameter of the observable universe to be about 1.5×1053 kg. Since the expansion of the universe is known to accelerate and will become exponential in the future, the light emitted from all distant objects past some time dependent on their current redshift will never reach the Earth. In the future all currently observable objects will slowly freeze in time while emitting progressively redder and fainter light. For instance, objects with the current redshift z from 5 to 10 will remain observable for no more than 4–6 billion years. In addition, light emitted by objects situated beyond a certain comoving distance (currently about 19 billion parsecs) will never reach Earth.

Beyond the Cosmos - Size - Netflix

a        (        t        )        =                              1                          1              +              z                                            {\displaystyle !a(t)={\frac {1}{1+z}}}  .

WMAP nine-year results combined with other measurements give the redshift of photon decoupling as z = 1091.64±0.47, which implies that the scale factor at the time of photon decoupling would be ​1⁄1092.64. So if the matter that originally emitted the oldest CMBR photons has a present distance of 46 billion light-years, then at the time of decoupling when the photons were originally emitted, the distance would have been only about 42 million light-years.

The comoving distance from Earth to the edge of the observable universe is about 14.26 gigaparsecs (46.5 billion light-years or 4.40×1026 meters) in any direction. The observable universe is thus a sphere with a diameter of about 28.5 gigaparsecs (93 Gly or 8.8×1026 m). Assuming that space is roughly flat (in the sense of being a Euclidean space), this size corresponds to a comoving volume of about 1.22×104 Gpc3 (4.22×105 Gly3 or 3.57×1080 m3). The figures quoted above are distances now (in cosmological time), not distances at the time the light was emitted. For example, the cosmic microwave background radiation that we see right now was emitted at the time of photon decoupling, estimated to have occurred about 380,000 years after the Big Bang, which occurred around 13.8 billion years ago. This radiation was emitted by matter that has, in the intervening time, mostly condensed into galaxies, and those galaxies are now calculated to be about 46 billion light-years from us. To estimate the distance to that matter at the time the light was emitted, we may first note that according to the Friedmann–Lemaître–Robertson–Walker metric, which is used to model the expanding universe, if at the present time we receive light with a redshift of z, then the scale factor at the time the light was originally emitted is given by

Beyond the Cosmos - References - Netflix


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