What happened in the first second after the Big Bang? Super-sensitive, superconducting microwave detectors, built at NIST, and implemented at BICEP and Keck telescope arrays at the South Pole have allowed astrophysicists to find out some of the answers with new observational results. The Background Imaging of Cosmic Extragalactic Polarization (BICEP) results are indirect evidence for the existence of the elusive gravitational waves from the big bang itself. By using highly sensitive microwave detectors, developed at the National Institute of Standards and Technology (NIST), telescope cameras can detect the polarization direction of photons emitted from the moment of last scattering between the photons and electrons in the plasma of the early universe, before stars and galaxies could form. These photons make up the CMB Radiation, which radiated outward after electromagnetic radiation decoupled itself from the plasma state of matter in the early universe, as the plasma formed into a gas, making space transparent for the first time. The photons emitted at the moment of last scattering, 13.7 Billion years ago, were gamma ray photons. Since then, they have been travelling almost uniformly, in every direction across the universe. Since the universe is expanding, these photons have stretched with the fabric of spacetime as the universe expanded and this has stretched their wavelength from gamma rays to microwaves. The apparently uniform pattern of polarization in the CMB can be broken into two components. One, a curl-free, gradient-only component, the E-mode (named in analogy to electrostatic fields). The second component is divergence-free, curl only, and is known as the B-mode (named in analogy to magnetic fields). Cosmologists predict two types of B-modes, the first generated during cosmic inflation shortly after the big bang, and the second generated by gravitational lensing at later times. Now, the BICEP team has confirmed detection of the first type of B-modes, consistent with inflation and gravitational waves in the early universe This is not the first indirect evidence, as the decay of the orbit of the binary pulsar PSR 1913+16 or of the double pulsar PSR J0737-3039 is also calculated by General Relativity to match the theoretical models of gravitational waves from pulsars. Nevertheless it is the first such evidence of gravitational waves from the period of violent gravitational interactions in spacetime after the Inflationary Epoch making it a highly significant discovery. This is the missing piece of the puzzle in the confirmation of inflation in the standard cosmological model. Alan Guth, the theoretical physicist who predicted inflation, calculated that the universe in an early Big Bang model had severe fine tuning problems relative to the observed uniformity of the intensity of radiation across the CMB sky. The evidence of inflation comes from Einsteins Theory of General Relativity, where the inflation of the scalar field would create a huge gravitational shockwave as any torsion in spacetime in the early universe was straightened out by this inflation and was sent outward as gravitational waves which penetrated through the whole universe, changing the polarization paths of the CMB photons as the waves were embedded in space and time, until the influenced photons were detected on earth. In the coming years other experimental equipment are expected to make the first direct observations of gravitational waves, with the LIGO, VIRGO, GEO600 and KAGRA experiments. These are possible because in the 100 years since Einsteins prediction there has been a lot of technological progress in lasers, precision optics, electronic control systems, quantum electronics and computers and data analysis. These are things even Einstein could not have imagined back in 1916. The BICEP experiment is observing the effects of gravitational waves from almost 14 billion light years away in space and therefore 14 billion years ago in time, before stars and planets even formed. The BICEP experiment is looking at very-low-frequency gravitational waves (~80 cycles in 14 billion years). Meanwhile, laser interferometry experiments such as the LIGO, VIRGO and GEO600 experiments are looking for gravitational waves that are passing by Earth right now. These experiments are looking for gravitational waves with frequencies of hundreds of hertz, which should come from relatively local sources in space and time, such as neutron stars and black holes within our own Milky Way galaxy or our own group of galaxies. The LISA orbiting gravitational wave detector is also proposed to detect gravitational waves, using coordinated laser baseline interferometry in space. Future plans for upgrading these designs may even include using entangled photons for more sensitive gravitational wave detection. All of this work is giving humanity an increased spectrum of vision for detecting phenomena in the cosmos. youtube/watch?v=QCbk4afiF1c
Posted on: Sat, 29 Mar 2014 10:14:02 +0000
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