Gravitational Waves Detected from The Big Bang?
Δημοσιεύτηκε στις 21 Μαρ 2014
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 Einstein's 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
Einstein's 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.
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 Einstein's 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
Einstein's 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.
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