The gravitational waves detected by LIGO tend to be in the frequency range of a few tens of Hertz to a few hundred Hertz. That’s not just a coincidence – it’s the frequency that LIGO is designed to operate at, and that in turn is because that’s the frequency at which it’s expected that some of the most common relatively powerful gravitational wave sources in the sky occur at. It’s also a feature of the design of the instrument, with higher frequencies limited by the laser power (more photons = more sensitive) and lower frequencies limited by things like the seismic isolation, thermal variations in the mirrors and suspension, and a range of other things. If you are interested in finding out more, you should play Space Time Quest.
Because frequency range to which LIGO is sensitive is is within the human hearing range, it’s possible to convert the gravitational wave signals directly into sound. They’re often a bit low, so it’s common to shift them up in frequency – it can be that’s not really any different from shifting infrared data into the visible to make an image we can actually, well, see! The result, in the case of GW150914 (the first gravitational wave detection) is a sound like the one below. Continue reading →
Last week Patrick Sutton and I recorded an episode of BBC Science Cafe, a weekly BBC Radio Wales show hosted by Adam Walton. The show was broadcast earlier this evening, and you can listen to it here – at least for about a month after first broadcast (and probably only in the UK). Continue reading →
It can be hard to have missed the news last week of the detection of gravitational waves – an event known as GW150914 [GW = Gravitational Wave, followed by the date of the event in the YYMMDD format]. There was, understandably, an awful lot of excitement – it hit pretty much every major news network, and was even mentioned at the BAFTA award ceremony (which is how we know we’ve made it…)!
In the weeks in the run-up to the detection there was a lot of talk about analogies and comparisons of the event, and the black holes involved. But how is that all calculated, and how does that compare to other things in the Universe? Continue reading →