Archive for Noise

Teaching Improvisation

Posted in Biographical, Education, Maynooth with tags , , , on September 29, 2020 by telescoper

The sudden switch of all our teaching online on Friday has necessitated a certain amount of improvisation. I had intended to do my introductory session on Mechanics and Special Relativity to first-year students as a kind of interactive workshop using the blackboard in Physics Hall. When we were told to move everything online I thought I’d just do yesterday’s session from my office which has quite a good blackboard and a setup I had already tested. Unfortunately however an office refurbishment project I was assured would be finished before the start of teaching but which has barely started meant that yesterday there was constant hammering and drilling in the Department. That made it impossible to do an online lecture (or do anything else) in my office. I knew there would be nobody in Physics Hall, though, so I did the lecture there to an empty room.

The camera provided in that room is fixed to a monitor at once side of the theatre and is therefore useless for capturing the blackboard, so I used my laptop camera plus a handy litter bin to raise it up. It wasn’t great but was better than nothing.

You might ask why I don’t do this from home. The answer to that is that I haven’t yet got an internet connection in the new house, so I can do online activities from there.

You might also ask why a refurbishment job, which could have been completed at any point during the summer when the building was empty, has only just started now we’ve started teaching again. If I had an answer I would tell you. I think the six people whose offices are currently unusable would like to know too, though at least they can work from home. It’s tough enough trying to keep everything together these days without this.

Fortunately today a colleague in the Department of Psychology found me a quiet place to work. It’s a small windowless cubicle normally used for experiments. At least it’s quiet. I think the next step will be a padded cell somewhere.

What kind of thing is GW190814?

Posted in The Universe and Stuff with tags , , , , , , , on June 24, 2020 by telescoper

There’s been a lot of interest in the past day or two over an event that occurred in the LIGO detectors last August, entitled GW190814. A paper has appeared declaring this to be “the observation of a compact binary coalescence involving a 22.2–24.3 M  black hole and a compact object with a mass of 2.50–2.67 M “. That would be interesting of course because the smaller object is smaller than the black holes involved in previous detections and its mass suggests the possibility that it may be a neutron star, although no electromagnetic counterpart has yet been detected.  It’s a mystery.

I was quite excited when I saw the announcement about this yesterday but my enthusiasm was dampened a bit when I saw the data from the two LIGO detectors at Hanford and Livingston in the USA and the Virgo detector in Italy.

Visually, the Livingston detection seems reasonably firm, but the paper notes that there were thunderstorms in the area at the time of  GW190814 which affected the low-frequency data. There doesn’t look like anything at all but noise in the Virgo channel. The Hanford data may show something but, according to the paper, the detector was “not in nominal observing mode at the time of GW190814” so the data from this detector require special treatment. What you see in the Hanford channel looks rather similar to the two (presumably noise) features seen to the left in the Livingston plot.

I know that – not for the first time – I’m probably going to incur the wrath of my colleagues in the gravitational waves community but I have to sound a note of caution. Before asking whether the event involves a black hole or a neutron star you have to be convinced that the event is an event at all.  Fortunately, at least some of the data relating to this have been released and will no doubt be subjected to independent scrutiny.

Now I’m going to retreat into my bunker and hide from the inevitable comments…

Wind turbines aren’t noisy!

Posted in Uncategorized with tags , on September 27, 2011 by telescoper

I read this morning that a petition to the Welsh Assembly Government has been raised demanding that wind farms be switched off from time to time to give local residents “some respite from the noise they make”.

In fact wind turbines, even big ones, make far less noise than people seem to think, and certainly less than motor vehicles. So if you’ve got an objection to wind farms, please make it an honest one.