Jump to content

Recommended Posts

Quote

The big news of that first sighting broke on 11 February 2016. In a press conference, senior members of the collaboration announced that their detectors had picked up the signature of gravitational waves emitted as a pair of distant black holes spun into one another.

 

The misgivings of Jackson’s group, based at the Niels Bohr Institute in Copenhagen, Denmark, began with this press conference. The researchers were surprised at the confident language with which the discovery was proclaimed and decided to inspect things more closely.

 

Their claims are not vexatious, nor do they come from ill-informed troublemakers. Although the researchers don’t work on gravitational waves, they have expertise in signal analysis, and experience of working with large data sets such as the cosmic microwave background radiation, the afterglow of the big bang that is spread in a fine pattern across the sky. “These guys are credible scientists,” says Duncan Brown at Syracuse University in New York, a gravitational wave expert who recently left the LIGO collaboration.

 

By the time the waves wash over Earth, they are extremely weak, and the sort of change in tunnel length we expect is equivalent to about a thousandth of the diameter of a proton. That is far smaller than the disturbances that come from background seismic tremors and even the natural thermal vibrations of the detector hardware. Noise is a huge problem in gravitational wave detections.

Hence why there are detectors in different places. We know that gravitational waves travel at the speed of light, so any signal is only legitimate if it appears in all the detectors at the right time interval. Subtract that common signal, and what is left is residual noise unique to each detector at any moment, because its seismic vibrations and so on constantly vary.

 

This is LIGO’s main ploy for extracting a gravitational wave signal from the noise. But when Jackson and his team looked at the data from the first detection, their doubts grew. At first, Jackson printed out graphs of the two raw signals and held them to a window, one on top of the other. He thought there was some correlation between the two. He and his team later got hold of the underlying data the LIGO researchers had published and did a calculation. They checked and checked again. But still they found that the residual noise in the Hanford and Livingston detectors had characteristics in common. “We came to a conclusion that was very disturbing,” says Jackson. “They didn’t separate signal from noise.”

 

The Danish team wrote up their research and posted it online. After receiving no response from the LIGO collaboration, they submitted it to the Journal of Cosmology and Astroparticle Physics. The journal’s editor, Viatcheslav Mukhanov of the Ludwig Maximilian University in Munich, Germany, is a world-renowned cosmologist. The editorial and advisory boards include top physicists such as Martin Rees from the University of Cambridge, Joanna Dunkley at the University of Oxford and Andrei Linde of Stanford University in California.

 

Mukhanov sent the paper for review by suitably qualified experts. Reviewers’ identities are routinely kept secret so they can comment freely on manuscripts, but these were people with a “high reputation”, says Mukhanov. “Nobody was able to point out a concrete mistake in the Danish analysis,” he says. “There is no mistake.”

 

The first step to resolving the gravitational wave dispute is to ask how LIGO’s researchers know what to look for. The way they excavate signal from noise is to calculate what a signal should look like, then subtract it from the detected data. If the result looks like pure, residual noise, they mark it as a detection.

 

Working out what a signal should look like involves solving Einstein’s equations of general relativity, which tell us how gravitational forces deform space-time. Or at least it would if we could do the maths. “We are unable to solve Einstein’s equations exactly for the case of two black holes merging,” says Neil Cornish at Montana State University, a senior figure among LIGO’s data analysts. Instead, the analysts use several methods to approximate the signals they expect to see.

 

This use of precalculated templates is a problem, Cornish concedes. “With a template search, you can only ever find what you’re looking for.” What’s more, there are some templates, such as those representing the waves created by certain types of supernovae explosions, that LIGO researchers can’t create.

 

The challenge with all three methods is that accurately removing the signal from the data requires you to know when to stop. In other words, you have to understand what the residual noise should look like. That is exceedingly tricky. You can forget running the detector in the absence of gravitational waves to get a background reading. The noise changes so much that there is no reliable background. Instead, LIGO relies on characterising the noise in the detectors, so they know what it should look like at any given time. “A lot of what we do is modelling and studying the noise,” says Cornish.

 

Jackson is suspicious of LIGO’s noise analysis. One of the problems is that there is no independent check on the collaboration’s results. That wasn’t so with the other standout physics discovery of recent years, the Higgs boson. The particle’s existence was confirmed by analysing multiple, well-controlled particle collisions in two different detectors at CERN near Geneva, Switzerland. Both detector teams kept their results from each other until the analysis was complete.

 

By contrast, LIGO must work with single, uncontrollable, unrepeatable events. Although there are three detectors, they work almost as one instrument. And despite there being four data-analysis teams, they cannot work entirely separately, because part of the detection process involves checking that all the instruments saw the signal. It creates a situation in which each positive observation is an uncheckable conclusion. Outsiders have to trust that LIGO is doing its job properly.

 

And there are legitimate questions about that trust. New Scientist has learned, for instance, that the collaboration decided to publish data plots that were not derived from actual analysis. The paper on the first detection in Physical Review Letters used a data plot that was more “illustrative” than precise, says Cornish. Some of the results presented in that paper were not found using analysis algorithms, but were done “by eye”.

 

Brown, part of the LIGO collaboration at the time, explains this as an attempt to provide a visual aid. “It was hand-tuned for pedagogical purposes.” He says he regrets that the figure wasn’t labelled to point this out.

 

This presentation of “hand-tuned” data in a peer-reviewed, scientific report like this is certainly unusual. New Scientist asked the editor who handled the paper, Robert Garisto, whether he was aware that the published data plots weren’t derived directly from LIGO’s data, but were “pedagogical” and done “by eye”, and whether the journal generally accepts illustrative figures. Garisto declined to comment.

 

There were also questionable shortcuts in the data LIGO released for public use. The collaboration approximated the subtraction of the Livingston signal from the Hanford one, leaving correlations in the data – the very correlations Jackson noticed. There is now a note on the data release web page stating that the publicly available waveform “was not tuned to precisely remove the signal”.

 

The Danish group’s independent checks, published in three peer-reviewed papers, found there was little evidence for the presence of gravitational waves in the September 2015 signal. On a scale from certain at 1 to definitely not there at 0, Jackson says the analysis puts the probability of the first detection being from an event involving black holes with the properties claimed by LIGO at 0.000004. That is roughly the same as the odds that your eventual cause of death will be a comet or asteroid strike – or, as Jackson puts it,”consistent with zero”. The probability of the signal being due to a merger of any sort of black holes is not huge either. Jackson and his colleagues calculate it as 0.008.

 

https://www.newscientist.com/article/mg24032022-600-exclusive-grave-doubts-over-ligos-discovery-of-gravitational-waves/

Edited by killing raven sun
Link to post
Share on other sites

I must admit I didn't believe the announcement when I first heard it

It was switched on right at the correct moment to pick up the passing  gravitational waves of colliding  black holes that just happen to collide at the correct instant in time light years away,bullshit!

If you know about the work of Nassiem Harramien and his predictions , there is a black hole in the center of every galaxy  if this is indeed the case  and galaxies collide all the time over the eons, you would have to wonder where are all the other gravity waves and why weren't they detected also.

I haven't looked into it but being rather suspicious of science in general,one would have to wonder about the coloration between the timing of the  funding renewal for the project and the apparent detection of said gravity waves

Edited by peter
Link to post
Share on other sites

the first and biggest problem with LIGO is that the experiment is illogical

 

the idea that a wave is moving without a medium is impossible, end of experiment

 

the idea that a gravity wave would be measurable is impossible, if the wave affects all materials the same way then there can be no measure unless you have a material not affected by gravity, end of experiment

 

if the data you gather is 100% noise then any result, or even no result, can be induced by algorithm, end of experiment

 

this kind of chicanery should not have made it past the planning stage much less being held up as "science"

 

the only scientific endeavor going on here is to see how much bullshit people will swallow

  • Like 1
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...