Wave Physics with LIGO data
Learn about sources from their signals
Sources and signals
Key ideas:
- Sources with high frequency motion prouduce high frequency signals
- Musical instruments display the connection between signal frequency and source properties
- In astronomy, we learn about the sources (stars and black holes!) by studying their signals (light and gravitational waves!)
Sound Waves
Lower pitch sounds have longer wavelengths. Musical instruments are designed to resonate with the pitches they produce, meaning that music from an instrument has wavelengths that match the length of the instrument. This is why larger instruments have lower sounds. You can often hear something similar in animals: larger animals tend to make lower pitch sounds.Low Frequency
Long Wavelength
High Frequency
Short Wavelength
Low Frequency
High Frequency
Long wavelength sound: large source
Short wavelength sound: small source
Long wavelegnth sound: large source
Short wavelength sound: small source
Low Pitch
High Pitch
Long wavelength sound: large source
Short wavelength sound: small source
Light
The colors we see in visible light correspond to different frequencies of electromagentic waves. Rainbows sort light from the lowest frequency we can see (red) to the highest frequencies we can see (blue or violet).Light from "thermal radiation" reveals the temerature of the source. The frequency of the light tells us about the motion of the electrons in the source: the hotter the source, the faster the electrons are moving, and so the higher the frequency of light that's emitted.
Low Frequency: Red Light
High Frequency: Blue Light
Cooler stars make red light
Hotter stars make blue Light
Gravitational Waves
Gravitational-wave detectors like LIGO and Virgo can record signals from mergers of black holes. The frequency of the gravitational-wave signal corresponds to the frequency of the black hole orbit, just before merger. In their final moments, larger black holes orbit at lower frequencies, and smaller black holes orbit at higher frequencies. Because of this, we can measure the mass of black holes by the frequencies of their gravitational-wave signals.By playing a graviational-wave signal through a speaker, we can even hear it - so that just like instruments, a higher pitch tells us to expect a smaller source!
Larger black holes
merge at lower frequencies
Longer wavelength
Lower Frequency
Smaller black holes
merge at higher frequencies
Shorter wavelength
Higher frequency
Got the idea?
Try it!Contact: gwosc@igwn.org
Image / Audio sources
https://www.southamptonmusichub.org/news/2018/2/7/national-success-for-two-of-southamptons-gifted-young-musicianshttps://commons.wikimedia.org/wiki/File:Man_in_uniform_playing_piccolo.jpg
http://www.krugerpark.co.za/africa_lion.html
https://www.bluecross.org.uk/pet-advice/caring-your-kitten
https://www.chicagoreader.com/chicago/dcomposed-chamber-black-classical-string-quartet-family-dcompressed/Content?oid=78423193
https://www.thestrad.com/double-bassist-leon-bosch-on-avoiding-back-and-finger-injuries/1921.article
https://www.physicscentral.com/experiment/askaphysicist/physics-answer.cfm?uid=20080502092418
https://www.labroots.com/trending/space/14884/blue-supergiant-stars-twinkle
http://cse.ssl.berkeley.edu/bmendez/ay10/2000/cycle/redgiant.html
https://git.ligo.org/zoheyr-doctor/twirl
https://philharmonia.co.uk/resources/sound-samples/
https://freewavesamples.com/lion-roar