5 days ago


of points here for the

of points here for the jury. Is it true that you have been a leading force in planning to install a LIGO station in your old country India? ADHIKARI: Yes. VERITAS: And is it true that you said that the India LIGO has the advantage of being able to avoid the mistakes of the US LIGO? That you would redesign India LIGO? ADHIKARI: Yes, but that has nothing to do with the correctness of the LIGO discoveries thus far. VERITAS: Now, Professor Adhikari, Dr. De here has said many times that when there is something obviously wrong with an observing instrument, it is totally useless to discuss any results from it – no matter how impressive, no many times confirmed etc. Do you agree with that position? ADHIKARI: That’s truism. VERITAS: Very good. So we will proceed on that note and talk about the LIGO instrument. Then we will come back to the neutron star merger issue. Now, the citizens of the world have been constantly regaled with the fact that LIGO is so sensitive an instrument that it can sense a car driving by a mile away, waves lapping on the shores of the far ocean, a LIGO scientist pedaling his bicycle nearby …and so on. Are these stories correct? ADHIKARI: Yes, LIGO is indeed that sensitive. VERITAS: Is the point of this public education that if LIGO can astoundingly sense such things, it can also pick up gravitational waves from billions of light years away? ADHIKARI: Yes. VERITAS: Professor Adhikari, does LIGO pick up all these disturbances we have just spoken of in the same way – that is by the same instrumental mechanism – as it picks up gravitational waves? ADHIKARI: Well … er… no. These disturbances are picked up because things go haywire inside LIGO in random ways. A mirror may move, a laser beam may go out of alignment, etc. But a gravitational wave causes LIGO to respond in a very specific and very predictable way. VERITAS: Then LIGO picking up those disturbances says absolutely nothing about the LIGO sensitivity, does it? It is in fact a completely bogus story that has been spread around the world. ADHIKARI: We are using a science-popularizing technique. We were not trying to be pedantic here with the general public. VERITAS: I see. OK, for the sake of clarity, let us say the disturbances we have just spoken of that cause LIGO to go haywire in random ways are recorded by LIGO in Class A Operation which involves misalignment of the laser link, a mirror tilting off-axis etc. And the gravitational wave is picked up by Class B Operation which involves a perfectly aligned laser link and systematic movement of the 72

mirrors, along their axes only – without any rotational or sideways motion. Is this an acceptable framework for discussion? ADHIKARI Yes. VERITAS: Now, in this scheme, how would geomagnetic disturbances be picked up? ADHIKARI: They would be picked up in Class A Operation. VERITAS: So it is only gravitational wave – and nothing else – that concerns the Class B Operation? ADHIKAR: Yes. VERITAS: Professor Adhikari, what is Class B Operation? ADHIKARI: It is a very specific mode of actuation of LIGO. The two mirrors move forward and backward along their axes; and they move in concert, even though there is no mechanical or electromagnetic linkage between them. They have in fact been hung to move independently of each other. So these mirrors are in a kind of invisible entanglement – somewhat like quantum entanglement. When one mirror moves towards the apex of LIGO – the corner of the LIGO ell, the other moves away from that point. In this way the two mirrors move in lockstep. And the amplitude by which a mirror moves under the influence of a gravitational wave is on a scale of one ten-thousandth of a proton diameter. VERITAS: So LIGO is always operating in Class A mode. Only when a gravitational wave is incident, the Class B mode comes into play. Is this correct? ADHIKARI: Yes. In that case we have both Class A and Class B Operations occurring simultaneously. VERITAS: So when you detect a gravitational wave, what is the experimental evidence that Class B Operation has been actuated? What is the evidence that the mirrors are entangled as though through some mysterious, invisible bond? What is the evidence that the mirror displacement is near one tenthousandth of a proton diameter – a quantum-scale distance? ADHIKARI: We do not monitor these effects directly. We cannot. If the LIGO readout wiggle matches our model of black hole merger wiggle – after the removal of noise of course – then that fact in itself proves that Class B operation has taken place. VERITAS: So the matching of the two wiggles confirms in one fell swoop four independent theoretical conjectures: passage of gravitational wave; black hole merger; entanglement of mirrors; and the movement amplitude on a quantum scale. One endpoint agreement confirms four highly esoteric theoretical conjectures. Is that correct? ADHIKARI Yes. VERITAS: And you do not see any logical problem with this? 73