The LIGO team reported on June 15, 2016, their second confirmed detection of coalescing binary black hole pair generating a gravitational wave. This was published in Physical Review Letters,1 with an abstract that reads (with some editing in […]’s and emphases added):
We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5σ. The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 Hz, and reached a peak gravitational strain of [about] 3.4 × 10-22. The inferred source-frame initial black hole masses are 14.2 and 7.5 [solar masses, i.e. mass of the sun], and the final black hole mass is 20.8 [solar masses]. We find that at least one of the component black holes has spin greater than 0.2. This source is located at a luminosity distance of 440 Mpc [about 1.4 billion light-years] corresponding to a redshift of 0.09±0.03. All uncertainties define a 90% credible interval.
Estimated gravitational-wave strain from GW151226 projected onto the LIGO Livingston detector with times relative to December 26, 2015 at 03:38:53.648 UTC. This shows the full bandwidth, without the filtering used for Fig. 1. Top: The 90% credible region for a nonprecessing spin waveform-model reconstruction (gray) and a direct, nonprecessing numerical solution of Einstein’s equations (red) with parameters consistent with the 90% credible region. Bottom: The gravitational-wave frequency f (left axis) computed from the numerical-relativity waveform. The cross denotes the location of the maximum of the waveform amplitude, approximately coincident with the merger of the two black holes. During the inspiral, f can be related to an effective relative velocity (right axis) given by the post-Newtonian parameter v/c=(GMπf/c^3)^1/3 , where M is the total mass. (Click on image for larger version.)
This result further strengthens the argument for stellar mass size black holes and for their correct prediction by Einstein’s general relativity. As I have written before this largely falls into the category of operational science. Some assumptions are necessarily required, but the waveform (see right) extracted from the received signal very precisely matches the expected waveform. Read What impact does the detection of gravitational waves have on biblical creation?2 Continue reading
The discovery of gravitational waves
Figure 1: The gravitational-wave event GW150914 observed by the LIGO Hanford (H1, left column panels) and Livingston (L1, right column panels) detectors. Times are shown relative to 14 September 2015 at 09:50:45 UTC. For visualization, all time series are filtered with a 35–350 Hz bandpass filter to suppress large fluctuations outside the detectors’ most sensitive frequency band, and band-reject filters to remove the strong instrumental spectral lines. Top row, left: H1 strain. Top row, right: L1 strain. GW150914 arrived first at L1 and 6.9 ms later at H1; for a visual comparison, the H1 data are also shown, shifted in time by this amount and inverted (to account for the detectors’ relative orientations). Second row: Gravitational-wave strain projected onto each detector in the 35–350 Hz band. Solid lines show a numerical relativity waveform for a system with parameters consistent with those recovered from GW150914 confirmed to 99.9% by an independent calculation (details in original). Shaded areas show 90% credible regions for two independent waveform reconstructions. One (dark gray) models the signal using binary black hole template waveforms. The other (light gray) does not use an astrophysical model, but instead calculates the strain signal as a linear combination of sine-Gaussian wavelets. These reconstructions have a 94% overlap. Third row: Residuals after subtracting the filtered numerical relativity waveform from the filtered detector time series. Bottom row: A time-frequency representation of the strain data, showing the signal frequency increasing over time. (Caption edited from the original, Ref. 6.)
On 14 September 2015 at 09:50:45 UTC the two gravitational wave detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO)—one at Hanford, Washington and the other at Livingston, Louisiana—simultaneously observed a transient gravitational-wave signal. The signal exhibited the classic waveform predicted by Einstein’s general relativity theory for a binary black hole merger, sweeping up in frequency from 35 to 250 Hz, and exhibited a peak gravitational-wave strain of 1.0 × 10−21 at the detectors.1
The two detectors recorded the same signal, which matched the predicted waveform for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a statistical significance greater than 5.1σ (where 1σ represents 1 standard deviation).2 In other words, the detection is highly likely to be real.
The source lies at a luminosity distance of about 1.3 billion light-years corresponding to a redshift z ≈ 0.09.3 The two initial black hole masses were 36 M⊙ and 29 M⊙,4,5 and the final black hole mass is 62 M⊙, with the equivalent of 3 M⊙ radiated as gravitational waves. The observations demonstrate for the first time the existence of a binary stellar-mass black hole system but, more importantly, the first direct detection of gravitational waves and the first observation of a binary black hole merger. Continue reading
In March 2014 a team of astrophysicists announced to the world, through a public press release, that they had made the biggest discovery of the 21st century. Using the BICEP2, a telescope located at the South Pole they claimed that they had discovered evidence of the early inflation epoch of the big-bang universe. This was in part identified through what they claimed was the signature of primordial gravitational waves generated by distortions in spacetime during the first quintillionth of a quintillionth of a second after the alleged big bang and the effect of gravitational lensing on the B-mode polarization of the CMB photons1 that have travelled for allegedly the past 13.4 billion years since they left the big-bang fireball. The discovery was celebrated worldwide and some even spoke of a Nobel prize for the work.
Scientists dispute claims
Soon after the announcement on March 17th 2014 I pointed out the logical fallacy of this sort of thing. Cosmology is not science in the usual sense of experimentally repeatable tests. Cosmology is really historical science and as such there could be a plethora of possible explanations for the same evidence. Then a short while after the champagne corks had been popped, leading cosmologists, including Lawrence Krauss, also questioned the premature announcement stating, Continue reading
Astrophysicist Dr Jeff Zweerink works for the Hugh-Ross-led organization Reasons to Believe. He recently wrote the above article. Relevant portions of his words are reproduced (in green) with my comments interspersed.
A remarkable correspondence exists between inflationary big bang cosmology and the Bible’s accounts of the universe’s origin. [emphasis added]
This is his summary statement which one assumes he will provide support for in the substance of his article. But if you look deeply into the details the substance evaporates. Continue reading
I was interviewed for a podcast by Vinnie and Joe Harned from Creation Astronomy Now
The discussion revolves around the so-called ‘smoking gun’ detection of the inflationary epoch of the big bang. See HAS THE ‘SMOKING GUN’ OF THE ‘BIG BANG’ BEEN FOUND? and the sequel HEY, NOT SO FAST WITH THE NOBEL PRIZE!
Already the alleged discovery of not only primordial gravitational waves but also the big bang era of inflation (which I discussed in Has the ‘smoking gun’ of the ‘big bang’ been found? and also in this blog, only a little over a week ago) has been questioned in a paper1 by leading cosmologists. This is in a paper, submitted to the preprint archive (arXiv.org) on March 20th, 2014, just three days after the press release (on March 17th) of the “discovery” by the BICEP2 Collaboration team.
On March 25th a press item appeared on phys.org quoting these cosmologists and entitled ‘Cosmologists cast doubt on inflation evidence’, with a storyline saying
Some theorists are advising that we “put the champagne back in the fridge”… at least for now.2
“Astronomers Just Detected the Beginning of the Big Bang”, “Big Bang’s Smoking Gun Found”, “Astronomers Discover First Direct Proof of the Big Bang Expansion” and “Major Discovery: ‘Smoking Gun’ for Universe’s Incredible Big Bang Expansion Found” were some of the headlines on Monday 17 March 2014 around the web-based news media.
One article described it as follows:
Radio astronomers operating telescopes at the South Pole said Monday that they’ve discovered evidence that the universe ballooned out of the Big Bang due to a massive gravitational force generated by space itself. The discovery is being called the “smoking gun” for the Big Bang theory, and it could have huge implications for our understanding of our universes [sic] (and possible others).
Harvard-Smithsonian astrophysicist John M. Kovac and his team detected gravitational waves—tiny ripples in the fabric of space—that could be the first real evidence for the ‘inflation’ hypothesis of how the universe basically bubbled into being nearly 14 billion years ago. The discovery also suggests that our 14 billion light-years of space aren’t all that’s out there—our universe could be a tiny corner of something much, much bigger.