The LIGO project is a bit like a rich man's Michelson-Morley experiment. To simplify the explanation, they fire a laser beam into the centre of the contraption, which splits the beam sending it down two perpendicular 4km arms to mirrors. The beams bounce back to the centre and are redirected to a detector which checks to see if the peaks and troughs of the light waves are still aligned. Last week LIGO announced that the emerging waves were very very slightly not aligned, implying that the difference in the two arms' lengths had varied by 0.0001 times the width of a proton in a way that looked like the gravitational waves predicted by general relativity (GR) due to two black holes merging.
I've been asked whether this is relevant to MiHsC. The answer is that if it really is from a high acceleration distant process then 'no' since MiHsC usually only makes a difference to GR at very low accelerations or large scales (of the
order of 10^-10 m/s^2, or tens of kpc), and at higher accelerations MiHsC reduces
to general relativity since in that regime the MiHsC inertial mass tends towards the
gravitational mass (if it's due to local changes in light speed, then it might be relevant).
The search for new data is a fantastic thing, so LIGO should be congratulated for that. The thing that bothers me about the gravitational wave paper is whether the twin black-hole merger scenario they pigeon-holed it with can be falsified or tested independently? I suspect it can't, and so this is like a lot of post-modern physics: unfalsifiable.
Imagine someone invents a Theory of Exploding Mushrooms (TEM). They have brilliant success predicting small mushroom blasts at home. Then people using ear-horns hear odd bangs from the distant forest. "It's my theory of exploding mushrooms!", the scientist says in glee and enthusiastically calculates the size of the unseen mushrooms that may be exploding. No one can go to check this prediction, and some people grumble that with the greatest respect, the TEM actually only managed to predict 4% of the exploding mushrooms that have subsequently been seen on the edge of the forest, and also the theory is incompatible with the famous Theory of Quantum Fungi...
In the gravity wave paper (see below) they say that the merger and the 'ring down' of the black hole are consistent with each other given GR, but this is an example of fitting using a computer model. They have found the black hole model that fits the data, but no one can go and look. It is not falsifiable. So it is not science.
Carl Sagan once said: extraordinary claims need extraordinary evidence. This applies to this case. They are invoking extraordinary directly-invisible entities and this needs independent backup. I feel that the usual standards are not being applied to the pathway that the majority of physicists occupy.
References
Abbott, B.P. et al., 2016. Observation of gravitational waves from a binary black hole merger. PRL, 116, 061102. http://arxiv.org/ftp/arxiv/papers/1602/1602.03837.pdf
9 comments:
At least LIGO detected something and *most likely* it wasn't a microwave oven ;-)
Kimmo: Very true - data is always good. It's not the data I'm wary of, but the immediate pigeon-holing of it.
I agree mike, and I'd like to add another perspective. Not only is this not falsifiable, but there is no direct evidence of the likelihood of the distribution of these events. Fortunately, the LIGO detector is omnidirectional(?), but until we have a few more events on record, some caution is warranted. A perspective check. The event happened 1.3 billion years ago, and the tool to receive the signal has only been in existence for 20 years. Some odds, eh?
I visited the facility a few years back, so I am very happy they got some data, but I agree I would like a bit more data...!
@ Mike:
It just occurred to me, but if there is a minimal acceleration that is always going on, does this not imply that the whole physical way of thinking in terms of inertial frames is plain wrong? And all conclusions drawn from it?
Regards
Indeed, MiHsC implies there are no inertial frames. A big conceptual change, but with tiny physical consequences in our normal regime.
LISA Pathfinder, which is basically LIGO in space, could test MiHsC if the mission is extended.
From Wikipedia: https://en.wikipedia.org/wiki/LISA_Pathfinder
"A possible mission extension would perform some measurements to confirm the general relativity theory. By flying through the saddle point where the Earth and Sun's gravity cancel out, the spacecraft might prove whether Einstein's theory still holds when gravitational accelerations are extremely small. If it does, it would test theoretical alternatives of general relativity, such as Modified Newtonian Dynamics (MOND) and TeVeS.[19]"
The "Is it falsifiable?" thing is a bit of a red herring. For phenomena requiring high precision and noise control - e.g. neutrino reactions in a big tank of dry-cleaning fluid - , only theory can guide us. If the data fits the theory, then that's confirmation. If *no data* arises - e.g. non-observation of proton-decay - then that's disconfirmation of a slew of theories. Demanding multiple LIGOs to "confirm it independently" is a bit like asking for independent nuclear detonations to confirm nuclear theory - sure, you could do it (and we did) but do you really want to?
Of course, we should always be sceptical of GR "orthodoxy" dictating what can't be observed. Like all the Physics Grand Inquisitors (i.e. Learned idiots) who say EM-Drives or LENRs *can't* work, therefore there's no need to experiment and all observations *must* be mistaken. Gravitational Waves - and Black Holes - have similar Learned Idiots, who say they *can't* exist too. Unlike the Orthodox Learned Idiots, they get labelled as "cranks".
Ryan Pavlick: Thanks for your comment. I've just looked up LISA pathfinder. They say the L1 orbit is a 'possible mission extension'. I hope they do it!
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