Clamor of gravitational waves from merging black holes 'heard' for first time | Hacker News Reader

Clamor of gravitational waves from merging black holes 'heard' for first time

phys.org

50 pointswglb16 comments

I posted this at one of the previous stories posted, but it got buried quickly so I allow myself to repost it here, for those who want a bit more details about how they did it.

One of the collaborators had a presentation[1] of the project over at PIRSA[2] a couple of years ago. I found it very interesting, thought I'd share.

[1]: https://pirsa.org/20100068

[2]: https://pirsa.org/About

Crazy to think that we’re been observing the cosmos for thousands of years through a single sense and we only recently opened up a second one. What a time to be alive!

Actually there's also this from two days ago, using neutrinos to observe space: Drexel Physicists Produce New Images of Milky Way Galaxy https://news.ycombinator.com/item?id=36525455

I need to taste a supernova

I want to see x rays!

I just watched the video, and as far as I can tell they didn’t actually convert the wave form into sound and play it. I feel cheated.

They can do that with waves that come from LIGO because they happen to have frequencies that are audible when converted to sound. In this case the wave periods are measured in years rather than milliseconds.

To be specific, they measure waves with a frequency measured in nano-Hz, which means a period on the order of decades.

It's trivial to shift frequencies up or down

For the LIGO waves they didn’t need to since the frequencies corresponded to audio frequencies that are audible by human ears.

Yes but for those motivated to hear the low-frequency waves, adding a frequency shift to the end of the signal processing pipeline would've been trivial.

Since the incremental effort is so low, it really doesn't matter much what the original frequency range of a signal is.

> it really doesn't matter much what the original frequency range of a signal is

It does matter. The waves they measure have so low frequency they've barely measured a single period of it. The higher frequency waves are lost in the noise.

So what should they play? A single 1kHz note is pretty uninteresting.

I agree that's one way to look at it. I prefer the framing that the signal just isn't that interesting to listen to.

Compare to the cosmic microwave background - we have no problem converting microwaves to visible light (implicitly doing a frequency shift), but the picture you see doesn't vary despite us having had enough time to collect many cycles of data.

The gravitational background should be similar - even if we collected data for thousands of years we're not going to hear a cool 'bloop' like for black hole mergers because interesting transients just aren't in the signal.

Science really does advance one funeral at a time[0]. Covid helped a lot. Sadly, Einstein stil alive in heads of scientists.

[0]: http://mitsloan.mit.edu/shared/ods/documents?PublicationDocu...

Can you explain your meaning? I thought gravity waves were compatible with Einstein's model of gravity.

What is waved by gravitational waves if no medium? Where is the source of energy for gravitational force if no medium? Why light have Doppler effect if no medium? How photons are formed if no medium? And so on.

Any attempt to discuss these topics drops shadow at Einstein, an then he fight back.

I'm not trying to discredit Einstein, or Newton, etc, but we have much more information about Universe than 100 years ago, so we can make better theories. Moreover, "shutup and calculate" is not an answer for physicist, we need explanations.

Reply on news.ycombinator.com