Details on signal processing can be found here.
An arXiv paper by M. Chiaberge, et al. The puzzling radio-loud QSO 3C 186: a gravitational wave recoiling black hole in a young radio source? concludes that a 3e9 solar mass black hole was ejected at a speed of 2000km/sec by the action of gravitational waves.
The story was recently highlighted in the press:
Astronomers using the Hubble Space Telescope have spotted a supermassive black hole that has been propelled out of the centre of the galaxy where it formed. They reckon the huge object was created when two galaxies merged and was then ejected by gravitational waves. The discovery centres on galaxy 3C186, which lies about eight billion light-years from Earth and contains an extremely bright object that astronomers believe is a black hole weighing about one billion Suns. Most large galaxies, including our own Milky Way, contain such supermassive black holes at their cores, with these huge, bright objects being powered by radiation given off by matter as it accelerates into the black hole.
It looks like the ejected hole was quite efficiently ‘tractor beamed’ to its ejection velocity by the gravitational wave emission.
The calculations are quite simple here, at least to an first approximation. There is a black hole formed of total mass 3 billion solar masses (using the arXiv paper as a source for all calculations). Since a solar mass black hole has a Schwarzschild radius of 3 km, that makes for a object diameter of about 18 billion km, which is also of order of the wavelength of the waves involved in a gravitational merger.
The merger time when 80% of the energy is released is roughly 100 M for two holes of mass M merging, we have M = 1.5e9 solar masses, so the light travel time is about 1.5e9*3km/3e8meters/sec or 16,000 seconds is M in this case. 100 M is the time where all the energy comes out – AKA the chirp.
So about 1,600,000 seconds is the relevant time. (For GW150914 that LIGO saw the same time would be 0.03 seconds – the holes were only 30 solar masses).
A total interaction time of 20 days. So the black hole is accelerated to a speed of 2000km/sec over 1,600,000 seconds. Thats an acceleration of 1 m/sec^2, or about 1/10 of earths gravity – funny how the numbers work out to be an acceleration that is an understandable number. The force is huge: F = ma or 1 x10^40 newtons. The total kinetic energy is KE = 1/2 (3e9 solar masses)*(2000km/s)^2, 1.2×10^52 J.
From a conservation of momentum we can get the total momentum of the gw E/c = (3e9 solar masses)*(2000km/s) –> 10^54 J of gw energy, this much energy was in a region about 18 billion km wide, say 1,600,000 seconds long, so an average of 1e13 J/metre^3, with a peak likely 5x that. We have an h for that from a typical expression for energy in a gravitational wave: so h = sqrt(32*pi*G*tGW/(w**2c**2)).
Wolfram shows h as 0.8 for these values (h can not be bigger than 1, anything over 0.1 means you need to use full non linear to get accurate results). In other words the math points to some sort of maximal connection – the gravitational waves must have been very connected to the structure. Gravitational waves while only weakly connected to something like LIGO are very strongly connected – a high coupling constant – to areas with large curvature.
This is already known in the land of GR. My idea is that particles expose areas of very large curvature (naked singularities) and hence also couple extremely well to gravitational waves. Well enough that we can construct electromagnetism as an emergent phenomena of GR.
Ian Sample has a 38 min talk with Gerard t’Hooft about a paper he presented at EmQM2011 in Vienna. The EmQM conference is held every two years, in 2015 I presented a poster called Can a sub-quantum medium be provided by General Relativity?. He also chats with Kings College London’s Dr Eleanor Knox, for some historical perspective, and Professor Carlo Rovelli for a bit about the, relational interpretation of quantum mechanics.
The 20th century was a golden one for science. Big bang cosmology, the unravelling of the genetic code of life, and of course Einstein’s general theory of relativity. But it also saw the birth of quantum mechanics – a description of the world on a subatomic level – and unlike many of the other great achievements of the century, the weird world of quantum physics remains as mysterious today as it was a century ago. But what if strange quantum behaviour emerged from familiar, classical physics? How would this alter our view of the quantum world? And, more importantly, what would it tell us about the fundamental nature of reality?
Some notes while listening…
1min The Podcast starts off with Feynman’s guess snippet. Which is as funny as it is right.
2min That is followed by a very short well known (to quantum mechanics like us) intro to quantum mechanics.
4min Then – Ian actually uses the words ‘Emergent Quantum Mechanics’!
5-7min Gerard talks about the accuracy and weirdness of quantum mechanics.
8min Gerard – “Classical Physics is an approximation.” – not incompatible.
8min Ian brings out ‘God does not play dice’.
9min Knox – talks about the measurement problem. The collapse. The Copenhagen Interpretation.
10min Knox talks about emergent theories – like biology, thermodynamics. So is quantum mechanics emergent? – Will EmQM help with the measurement problem?
13min Gerard – perhaps the randomness of QM does arise from stochastic classical actions. The answer is no – its not classical – “its different to its bones” from classical. Its a fundamental difference. (i.e. Bell).
15min Gerard talks about the Standard Model of Particle Physics. – Lots of people think that is all we need.
16min Gerard says the SM+QM does not feel right. It lacks a certain internal logic. Gerard thinks that the laws of QM are something of an optical illusion, ‘what is it actually that we are describing’.
17min Gerard does not want to change the equations of QM. He keeps the equations of QM. (Tom says this is at odds with most EmQM practitioners today).
18-22min Ian asks if EmQM is controversial. Gerard says yes its controversial. Bell proves that its impossible to have a classical computer reproduce QM. But Gerard has looked at the small print, and finds a way around the Bell theorem – by long range correlations – linked. This correlation is the heart of QM and is not weird – but needs a natural explanation.
22min Ian asks if this solves ‘Spooky action at a distance’. Gerard says yes it does these correlations can explain these peculiar correlations.
23min Ian says Knox calls Gerards plan ‘superdeterminism’.
25min Ian asks why do we need to change QM if it works so well? Gerard says the positive outlook on QM as being exactly correct is the Many World Interpretation. Gerard finds MWI ‘unsatisfactory’.
26min Ian points out that Gerard and EmQM are controversial.
27min Ian talks to Carlo Rovelli.
28min Carlo says we need to get used to QM – it will not be explained or overturned soon. The weakness in EmQM’s are that they do not lead to ‘new ways of thinking’ (Tom says what??). Then he talks about String theory and QM. We should just accept it as is.
30min Ian talks to Gerard about being comfortable with a theory that like QM. Gerard says that the present situation is bad with the MWI multiverse. Gerard thinks that while this works its ‘unsatisfactory’.
31min Gerard – the MWI shows that we are not there yet. We have not found the right description for our universe. All we have today are templates – that is our description, but its not what it actually is.
34min Carlo – his relational theory. Which is not MWI. Take QM seriously, relational QM takes QM at face value. The properties of objects are always measured with respect to something else. Velocity is the property of an object relative to something else.
36min Carlo starts talking about quantum gravity. We need to use relational QM to help us get to quantum gravity.
37min Science is a long sequence of us discovering that we were wrong. The world is different. If we end up agreeing on QM then this changes realism and philosophy – which Carlo thinks that will be the case. QM is the final theory for him.
Its quite reasonably done. Host Dr. Matt O’Dowd takes a 15 min tour through the history of the theory, mentioning John von Neumann, David Bohm, Einstein, Louis de Broglie, Niels Bohr and others. The basics are there and the level is a large step higher than TV, making it good to watch even if you know all the basics already. Since 90% of popular physics over the past decade has been on strings and the multiverse, I feel its great when a theory that actually has a possibility to be correct gets some air time, so that’s why I am mentioning it here.
Matt mentions this video by Veritasium which has 1.3 million views! I thought QM interpretations was a backwater in the physics backwater, but its seems not always.
Matt has an account at patreon here where you can catch up with other PBS video https://www.patreon.com/pbsspacetime , and Veritasium has one here https://www.patreon.com/veritasium .
While I’m not sure myself that the EM drive actually works, the authors of the recently published EM Drive paper promote a realist interpretation of QM in order to explain the EM Drive’s thrust.
In the approach used in the quantum vacuum plasma thruster (also known as a Q thruster) supporting physics models, the zero point field (ZPF) plays the role of the guiding wave in a similar manner to the vacuum-based pilot-wave theories. To be specific, the vacuum fluctuations (virtual fermions and virtual photons) serves as the dynamic medium that guides a real particle on its way. ...... If the vacuum is indeed mutable and degradable as was explored, then it might be possible to do/extract work on/from the vacuum, and thereby be possible to push off of the quantum vacuum and preserve the laws of conservation of energy and conservation of momentum.
This widely distributed paper puts the ideas of realist interpretations of QM in the news, as evidenced by articles here, here and here. That’s good in my opinion, as more eyes on the field, the better. Some may think that conflating the EM Drive with an emergent quantum mechanics will only harm the field once the EM Drive is put to rest in a few more years, but that’s not how publicity works.
There has been a lot of action about these drives over the past decade or two. I am totally open to new ‘unexplained’ physics, but one wonders why this phenomena has not been experimentally accepted after all this time and energy. For reference’s sake, a long awaited upheaval of physics may come from an unexplained yet established result along these lines, but Kuhn’s ideas suggest that well established theories can explain any result, and so we may instead have to look for theories that provide simpler explanations for established experimental results.
The Ligo measurement is the greatest thing to happen in Physics and Astronomy for decades. Amazing work. It was about 50 years ago that the first gravitational wave detector was built by Weber. It took 50 years of refinement, many PhDs postdocs and full careers, but the LIGO team did. it.
I will assume that you have already read the paper and other popular sources on this observation, so I will jump into what excites me about this observation:
How much energy? Three solar masses worth of gravitational waves were emitted over just a few tenths of a second. The paper reports a peak gravitational energy emission of 200 solar masses per second! See the paper for errors on this estimate but its accurate to within 20%. The really amazing thing though is that this emission took place from a region only about 200 km across. The frequency of the waves at peak emission is (from the paper fig 1 – bottom row) 120 Hz or so.
Lets look at that amount of energy in terms of another form of energy that we are more comfortable with – electromagnetic waves – light. I want to compare this to the “Schwinger limit” – which is the maximum electromagnetic field that can occur before quantum pair creation effects take over. The Schwinger limit controls the maximum power that a region of space can transmit through itself (via opposing overlapping lasers say).
Say we had standing radio waves at 120Hz in a 200km on a side box, how much power could such an area radiate if it were only limited by the Schwinger limit? (i.e. ignore the mechanism by which such spectacular amounts of energy could be turned into radio waves).
The formula for energy density given an electric wave is quite simple: See for instance this hyper physics page:
Total Energy density = ε*E2 So at the Schwinger limit of 1.3×1018 V/m and with the constant ε being 8.854187817620… × 10-12 Farads/m, we get 1.5×1025 kg/m/s2. We have 200,000 metres per side, so there are 1.2×1041 J (joules) in a 200km on a side box at the Schwinger limit.
How many joules of gravitational wave energy were held in a 200km box around GW150914? Well at 200 solar masses per second emitted, we need to take the size of the box and use light travel time to determine the amount of energy in the box at any one time: So 200 solar masses per second. Light travel time is 200km/(3e8m/s) = 6.7×10-4 seconds. So if that volume emits 200 solar masses of energy per second, then that is 0.13 solar masses worth of energy at any one time in that volume, or 2.3×1046 Joules! This is some 5 orders of magnitude above what can be emitted by this same region using electromagnetic means!
The mechanism by which one arrives at the Schwinger limit is conceptually simple – ‘QED non linear photon – photon scattering’ involving electron – positron pair creation. (See the wikipedia article for a start).
Is there a corresponding quantum ‘Schwinger limit’ for gravitational waves (gravitons)? Well there is of course a limit in place due to classical general relativity, which is well known. In this case we are close (gravitational h is about 0.001 or so?) of the classical limit, which is basically that you can’t pile anything up so that the density would cause a black hole to form. But is there a feynman diagram for graviton – graviton scattering – well of course there is – it should behave like real classical gravity! I guess what I am wondering – is there another pathway where graviton scattering would take place and according to QM make the GW150914 ‘impossible’?
Does the observation of gravitational waves 5 orders of magnitude stronger than the strongest possible electromagnetic wave mean that we can finally stop calling gravity the weakest force? Yes to that!
My take as anyone who reads any of this site will know is that electromagnetism, quantum mechanics and the nuclear forces are all emergent phenomena from classical general relativity (see my poster). To me this observation is another hint at what general relativity can do.
As a further note, this corresponds to 0.018 watts per square metre at the 1.3 billion LY distance of the earth! That means that the earth had 2.3 Terawatts of gravitational energy passing through it on Sept 14 2015, just from this one event. Yet this massive amount of power is barely within observational limits of LIGO. LIGO sees only nice correlated bumps (with only 2 detectors its not really built to look at the background of gravitational wave energy), so we could easily have this much energy passing through the earth in the form of these stochastic low frequency gravitational waves all the time, and LIGO would not be able to detect it.
Gravitational waves make the perfect sub-quantum excitation – they can carry very large amounts of energy without anything but a carefully designed detector being able to pick them up.
Other than the actual LIGO observatory of course (which I argue below may not be the ideal gravitational wave detector).
A nice isolated black hole maximally spinning at near a = 1, and of the same approximate mass as the GW150914 emitter would exchange a substantial amount of the incoming wave energy into motion – and it would pick up something like 0.2 GW of power for a fraction of a second, which would likely be observable since this hypothetical black hole is sitting so nice and quiet, a GJ of energy exchange would cause small (since the thing is so heavy) but measurable effects.
Say we don’t have a nearby system (we would need varying sizes to couple to the frequencies we wish to monitor) of quiet black holes to listen to. What else could we build? The ideas opens up if one assumes that matter and light are both gravitational phenomena. What would be ideal is something that mimics a tuned superradiant like interaction with gravitational waves, but it trillions of times lighter and made of ‘ordinary matter’. What makes super radiance work?
“What happened is that because this Rydberg atom stayed very high excited, but up there the energy levels are very-very close together. What does that mean? The transitions have very long wavelengths. So basically every sample that you can have is very small compared to these long wavelengths. And so superradiance is actually quite likely in these cases. And this is actually exactly what happened. As I said, it was an accident, I don’t think it could have been done such an ideal experiment on purpose in this case.”