The Gravitational Wave Background - Sixty Symbols

Oliver Gould & Swagat Mishra discuss groundbreaking findings in the field of gravitational waves. More links and info below ↓ ↓ ↓
The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) Collaboration: nanograv.org
Oliver Gould and Swagat Mishar are physicists at the University of Nottingham. More about the School of Physics and Astronomy at: bit.ly/NottsPhy...
More Sixty Symbols videos:
Black Hole Mergers and Multi-Messenger Astronomy - • Black Hole Mergers and...
Primordial Black Holes - • Primordial Black Holes...
Primordial Gravitational Waves - • Primordial Gravitation...
Golden Cubes and Gravitational Waves - • Golden Cubes and Gravi...
Gravitational Waves Discovery - • Gravitational Waves Di...
LHC Videos - • Large Hadron Collider ...
Some relevant papers:
The NANOGrav 15 yr Data Set: Search for Signals from New Physics - ui.adsabs.harv...
The NANOGrav 15 yr Data Set: Evidence for a Gravitational-wave Background - ui.adsabs.harv...
The NANOGrav 15 yr Data Set: Observations and Timing of 68 Millisecond Pulsars - ui.adsabs.harv...
The NANOGrav 15 yr Data Set: Constraints on Supermassive Black Hole Binaries from the Gravitational-wave Background -
ui.adsabs.harv...
Chinese PTA - inspirehep.net...
Parkes PTA (Australia) - inspirehep.net...
European PTA and Indian PTA - inspirehep.net...
Dr. Oliver Gould - www.nottingham...
Swagat S Mishra - www.nottingham... and swagatam18.wor...
Sixty Symbols Patreon: / sixtysymbols
This project features scientists from The University of Nottingham
bit.ly/NottsPhy...
Video by Brady Haran and James Hennessy
www.bradyharanb...
Email list: eepurl.com/YdjL9

[@imadetheuniverse4fun]

Swagat Mishra's explanation was extremely clear! more of him please!

[@scottrobinson4611]

Swagat is a G

[@allenyordy6700]

Thank you Brady and team appreciate the video I’ve been waiting for something thanks again for all of your hard work

[@mrtienphysics666]

This type of channels are what made KZbin still relevant.

[@nannan3347]

I’m sure they’ll find some reason to ban this channel eventually.

[@casanova0102]

Your comment is negative and useless. Be happy

[@BondJFK]

@@nannan3347 I am a software engineer, I am thinking about making a website only for science video creators

[@as-qh1qq]

Observation of a wave that has a wavelength in lightyears blows my mind

[@-Kerstin]

Great video but the text overlay was mostly in the way in my opinion.

[@rohitchaoji]

I remember Swagat as a research fellow in IUCAA when I was just finishing my bachelors degree and fishing for opportunities to do projects under the faculty there. Didn't expect to see him on Sixty Symbols.

[@yearswriter]

As always, really great stuff.

[@arhythmic1]

The large text is distracting. Great video otherwise!

[@solanofelicio]

Great video as always. I'm starting my PhD next year on this topic. Hopefully we'll get better data from PTAs and LISA!

[@nicksamek12]

A very clear explanation for why gravitational waves can affect the pulsar timing but not rip us apart!

[@Currywurst4444]

When the space is in the process of getting more or less strechted, it speeds up or slows down the rate of the pulses from the pulsar. The pulsar itself isn't affected, only the signal on the way to us. To find a gravitational wave from this: The pulsars are a large number of lightyears apart so the only thing that matters is their direction in relation to earth. Depending on in which direction the pulsars were that changed and how long this change lasted you can determine the direction and wavelength of the gravitational wave.

[@kryvor]

The giant white text is so distracting. If you really want a “callout”, could you create an elegant “quote bubble” on the side? It would look less cheap and be less distracting.

[@DiCasaFilm]

Okay are we just gonna pass right by "holodeck" at 7:14? Haha. Anyone care to explain that?

[@crawkn]

The theorist vs experimentalist dichotomy is false, they aren't in competition. Theorists inform experimentalists regarding what data may be needed, and experimentalists inform theorists as to the fit of their theories to reality. It is teamwork. In a sense, a theorist doesn't even become a theorist until their conjectures or hypotheses are fit to experimental data, and experimental data is just scenery prior to being fit to a theory.

[@dan110024]

Absolutely love this content! Although really not digging the big text coming up over the screen. It's just distracting :)

[@underpowerjet]

Always blows my mind how amazing and creative we can be in finding ways to detect and measure these objects that are so far away from Earth. I am so excited for the future astronomy! Keep up the great work everyone!

[@stoatystoat174]

Great explanations. I always treasure this channel as one of the places to find out something interesting or find the interesting truth behind enthusiastic news science daftness :)

[@biaroca]

As much as I love the veteran professors of the channel, I also like seeing new faces too!

[@tbird81]

Thumbs down the video if you don't want anymore WRITING LIKE THIS over the screen.

[@dziban303]

I was really devastated to hear about Professor Merrifield

[@jonathansteiner9125]

I'm actually working on the interpretation of this :).this video just made my day

[@luqras]

Does the gravitational waves gets stretched with the expantion of the universe?

[@GeoffryGifari]

Particle physics started with cosmic ray experiments and now circle back to looking out to the cosmos

[@judgeminty7070]

I love these videos so much. I plan on making a shift into the physics field in the near future and have even the simplest understanding of these concepts before hand gives me a little more confidence making that move. The derivations keep making more and more sense 😁

[@jamie_ar]

Great video, although I'm not a fan of the text appearing randomly it's really distracting.

[@thebrookshome]

Idk, I like the text that calls attention to the key terms that are unfamiliar to me.

[@icepick117]

impact font is the font of the internet!

[@2Worlds_and_InBetween]

you can't please all of the people all of the time 😊

[@jamie_ar]

a better approach might be to have the text smaller so it doesn't take up the whole screen@@2Worlds_and_InBetween

[@MuitoDaora]

The TikTok era

[@emarsk77]

I love Swagat Mishra's hand gesturing.

[@TomLeg]

Gravity waves pass through pulsars ... will they pass through a black hole?

[@joshlewis575]

What if the background they're mentioning is the suction from the black hole our universe resides in? Like a balloon being blown up

[@CarBENbased]

Gravitational waves world be affected by the expansion of the universe correct? So is it possible that the background is just the result of early stellar mass mergers that have been stretched out?

[@garethdean6382]

No, because that also lowers their amplitude, their energy,to the point we'd not be able to detect them. However waves produced in the early universe *would* b stretched, but also have an amplitude big enough to still be detectable now, when their wavelength has been increased a thousandfold.

[@Rivulets048]

Glad grady isnt afraid of calling out the community when he said "this fits my idea" . This could challenge alot of convetional thought. Hopefull we dont let our hubris lead us to dead ends

[@AkshayaMishra-dx1ty]

Really great talks.

[@ccaudi]

Considering the age of the Universe, I'd expect a plethora of waves traveling through space passing through each other. As with other wave types, do gravitational waves interfere with one another?

[@drdca8263]

I suppose they must? How else would waves in the same value at the same place be? I suppose maybe you mean specifically, “do they destructively interfere in a persistent way at some location”, And... I think, in principle that could happen, but I think you would need two wave sources to have close to the same frequency? Which, seeing as the frequency of these waves changes as the two bodies orbit closer and closer, it seems like that would require quite a bit of a coincidence? But, I don’t know much about gravitational waves, and I could easily be wrong. Probably someone has written somewhere a nice derivation+explanation for “here’s how to approximate how gravitational waves travel by starting with a flat spacetime and linearizing some stuff” that should be approachable to people who aren’t experienced with GR, but I haven’t read one if there is such a thing, so my understanding is less than that of someone who has.

[@tomkerruish2982]

They can even attract each other and 'stick' together. Check out the entry on 'geon' (physics)' in Wikipedia.

[@GabrielACGama]

Yes, they interfere. I think that is why it took 15 years of data to model the gravitational wave background. There must be a lot of noise of multiple gravitational waves!

[@S....]

It's about how big those are here.

[@CheckmateSurvivor]

The Earth is Flat. Please follow me for more conspiracy facts.

[@DavidBeddard]

The idea to use pulsars like this was absolutely brilliant. I'm very excited for the developments in this field. The thought of probing back so close to the very beginning of everything as we know it... awesome! Truly awesome! Love it!

[@anrade86]

what I dont get is, how can we measure something that stretches the space-time fabric if our measuring insturments themselves are embedded in this fabric? It's like measuring an elastic piece of cloth with an elastic measuring tape

[@garethdean6382]

Because our instruments don't work the way you think. Imagine two objects in space, unconnected. When space compresses the two objects move closer together. Imagine a ruler across this space. You might think that the ruler will behave the same way, it will compress and measure no change. But this is wrong, the ruler's internal forces don't like compression, and resist it, the ruler tries to expand to its 'natural length', unlike the separated objects. The ruler *will* measure a change in distance. We see this with tides; the moon's gravity is stronger on on side of the Earth, space is more curved there. But the Earth doesn't 'curve with the space' so we don't notice anything, instead we get tides, warping of the Earth that can be used to measure the gravity gradient.

[@johnqpublic2718]

Experimental kit much, much bigger than the Earth indeed.

[@Kwauhn.]

I think that last quote "it's the first time we've had [an]... experimental kit that's so much bigger than the Earth" that drives home the excitement surrounding these new discoveries. Not only is this new science, but recent revelations and advancements in technology and analytic techniques are allowing us to take a second glance at what's before us so that we can gleam more than ever before. Growing up, for me, the COBE CMB was the deepest and most detailed view into the history of the universe. I'm not that old, and look at where we are now... It's amazing to think about what further discoveries the future may hold.

[@andybeans5790]

I like Mishra's voice, really pleasant accent and cadence

[@arslongavitabrebis]

Does gravitational waves have a negative gravitational effect in the lower part the wave? Waves can be reflected and refracted, does gravitational waves can as reflected, refracted or damped? Which is the smallest peace of mater than can create gravitational waves?

[@101Mant]

I believe theoretically all moving mass creates gravitational waves, it's just that you need a lot of mass for something you can measure, particularly at astronomical distances.

[@5ty717]

OG : Oliver don’t forget TIME- ENTROPY. If you wonder about particles v energy then don’t forget to apply your youth and clear intellect to TIME. It’s not just spacetime cause it is clearly at least one direction and deeply/intimately connected to gravity… and a waveform… or wave platform… wish i could help… but i try.

[@zhavlan1258]

Hello from Kazakhstan. The Dark Universe requires a lot of money from the budget: an experiment that sheds new light on the Universe will help save costs. We can create an educational and practical device and practically master Einstein’s theories of relativity or obtain, for example, new physics: Postulate 1. Light is an ordered vibration of gravitational quanta. Postulate 2. The gravitational field controls the frequency and speed of light in a vacuum. This is determined experimentally using a hybrid fiber optic gyroscope (based on Michelson's experiment 1881-2015). Using a hybrid fiber optic gyroscope, the straight-line speed of vehicles can be measured. There is a company in China that makes (fiber optic angular velocity meter) they will be able to create a hybrid device. Please, can you come to an agreement with them? I guarantee payment at cost on my part.

[@guyh3403]

This was soooo interesting! Thank you. The big letters? Nehh, not so much ;)

[@lumburgapalooza]

"One possibility is a black hole a billion times bigger than any we've observed... a pair of those colliding would produce these waves" Don't just _say that._ I have to sleep tonight.

[@brianmiller1077]

Light year scale wavelengths? I can't really put it into perspective.

[@arthurs5099]

Amazing! Hopefully in 10 years string theory will be dispoved and we will finally move on. Long live the anisotropic universe.

[@FlashMeterRed]

...... so pulsars are not good clocks because they've always been stretched and compressed by gravitational waves, and we've always observed that.

[@Jon-cw8bb]

The text on the screen was really annoying.

[@bjornmu]

I read some numbers somewhere from which I tried to find out how much the distance to these pulsars actually changed as a consequence of the gravitational waves. And I came up with a number of around 10 meters! 😮Were my calculations correct?

[@Triantalex]

ok?

[@henninghoefer]

Please stop it with the TikTok-Style text callouts...

[@randomfarmer]

I hate to say it, but how are gravitational waves all that different from ordinary waves of photons given off by, say planets ('noise' i.e.)?

[@fussyboy2000]

The error bars on astrophysics graphs are always enormous!

[@tomkerruish2982]

The joke decades ago was that cosmologists put their error bars in the exponents.

[@justinofearth]

maybe because the things they are measuring are enormous, and at enormous distances away/traveling enormous distances to get here

[@fussyboy2000]

@@justinofearth There's a joke about how astrophysicists take π = 1 because they just work in orders of 10.

[@nicksamek12]

It's an unfortunate thing to call it, as it groups it with the CMB which we associate with the Big Bang, while the CGWB isn't.

[@muzikhed]

Brilliant. Good to see young minds getting in on the scene.....What are Quarks made of ?? Ha ha ! Perfect.

[@plasmabazooka4403]

Please ask Oliver don't go to vocal fry. It is quite hard to listen.

[@priyabratadash381]

Great to see Swagat Saurabh Mishra...he is from my home state Odisha.

[@Ojisan642]

Mr. Mishra is an excellent explainer!

[@dl5244]

what can't pulsars have more than 2 jets and more than one rotational axis?

[@lorenbooker9486]

I thought I was watching Silicon Valley for a moment.

[@iamsandrewsmith]

Two great explainers of a complicated subject! One more explanation, if possible -- the use of the word "holodeck" in that paper. I mean, I'm sure many astrophysicists are Star Trek fans...

[@whatarewedoing0]

how strong is the signal compared to the ones we detected before with the merging black holes?

[@garethdean6382]

In what way?Statistically it's weaker than LIGO's detections, energy-of-the-waves-wise it's billions of times greater, in terms of energy density of the waves much less and the pulsar signals are pretty weak in comparison. There's a lot of different strengths involved.

[@whatarewedoing0]

how much did it distort space time compared to the other signal but word i got you lol@@garethdean6382

[@JATmatic]

"experimental kit a bit bigger than earth" *Light years bigger* :D

[@schitlipz]

I'm excited even though I don't know what it's about on a deeper level. Weird.

[@garethdean6382]

Essentially w have a list of pulsar signals and how they relate to each other. So, Pulsar #1's data started at second 4 and repeats every 100Ms, while Pulsar #2 started at second 5 and repeats every 150Ms. If nothing changes, then we know when the two signals will appear relative to each other, Pulsar #1 at 4.0,4.1, 4.2.. Pulsar#2 at 5.15, 5.3, 5.45... BUT if something affects Pulsar #1 and NOT Pulsar #2, then its signal might b delayed,say by 25Ms. Then all of a sudden #1's pattern goes something like 4.8, 4.9, 5.025, 5.125... We notice a change and importantly, we notice #2 DIDN'T change, so it can't be something that happened to US, that *would* affect *all* the pulsars. By looking at how only *some* signals change w can detect the influence of gravitational waves.

[@Ebutuoymaii]

What about the ray emissions from Antarctica?

[@robertbronsdon]

Electromagnetism is much stronger than gravity... But we can detect gravity "through" emr. Why is gravity "more" detectable through the emr space?

[@Kushb4an]

Bro has both Bihari and English accent. शा का सा ho Jaata hai. ❤❤

[@farabor7382]

Excellent video, loved the speakers!

[@Zeuskabob1]

Just a minor nitpick: SIGW-DELTA, GAUSS, and BOX are three different models for SIGW, so I'd have preferred if they all three got arrows.

[@JosBergervoet]

Is there an audio rendition of the background anywhere? Speeding up the 15 years to, say, 15 seconds would fit it right into the audible spectrum, I'd expect... (There were audio clips from the first black hole mergers, they did not need much speed-up.)

[@TacticusPrime]

What an exciting discovery! Imagine if we're seeing the creation of the first protons... or actual evidence for superstrings... damn...

[@StarryNightGazing]

Thank you, this is great stuff for my upcoming GWs exam!

[@renedekker9806]

OK...want to know so much more. Was it a single wave that passed through, if so what was its size? Is it a continuous wave, if so, does it have a steady frequency, and what is it? Is it a standing wave, or a moving wave? How do we know it is not a vibration of the Earth itself, affecting our clocks?

[@Eztoez]

40 seconds in and no idea what he's going on about.

[@shaunswett6684]

This is so exciting. Thanks for the great explanation. Gravitational lensing, and now this, neutron star timing as a kind of telescope. Think about what that means. Humans are actually using galactic resources for our advancement. Does that make us kind of an honorary Kardashev type 3 civilization?

[@amirpatel1934]

Great interview! what I am curious to know is, do gravitational waves imprint information about what they pass through into the waves? and how do gravitational waves formed in black hole-black hole mergers leave the event horizon especially if gravitational waves also move at the speed of light?

[@danieljensen2626]

1. Yes, I believe gravitational waves passing through a bunch of mass should be affected, somewhat like electromagnetic waves passing by an antenna. But it will probably be a while before we can characterize the signals well enough to look for stuff like that. And fortunately for this work the universe is almost entirely empty so the amount of mass these waves have passed through on the way to us is almost zero. 2. The gravitational waves don't come from inside the event horizon, as you guess that would be impossible. I'm not 100% sure but I think you could frame it as the gravitational waves being produced just outside the event horizon (where they can escape) as a result of the event horizon itself moving around.

[@amirpatel1934]

@@danieljensen2626 thanks for feedback mate. Just a quick response to number 2: a few years ago there were two black holes that merged but the final mass of the black hole didn't equal the two individual black holes before merger, the black holes lost several solar masses of mass in the form of gravitational waves. The mass of the black hole is centred within the event horizon no? So somehow that mass turned into GW which then escaped the event horizon. That or I've got this completely wrong.

[@bradley3549]

Seems to me that gravitational waves don't have to escape anything. They are ripples in the medium.

[@DwainDwight]

super interesting. well done all. keep it up.

[@marvelous1358]

This helped me understand the Cosmic Microwave background properly. Thank you

[@PetraKann]

Creative way of detecting large light-year scale wavelengths of gravitational waves. Could it be a remnant of the big bang itself like the CBR?

[@PeterGaunt]

Fascinating, Brady. Good to see you back. Where have you been? Other projects or taking a rest?

[@dubsar]

How can this discovery make the average human being less stupid, less selfish?

[@aidenbrazil7312]

Are gravitational waves susceptible to red shifting like electromagnetic waves?

[@iLLadelph267]

this is so awesome! as soon as LIGO made the initial gravitational wave discovery i thought there had to be a background but never thought it could be detectable in my lifetime! everything with mass exerts gravitational waves bc, well its matter moving thru spacetime. but gosh we needed some MASSIVE objects to see those waves, neutron star mergers. never would i have thought we could come up with a way to see as much as a gravitational wave background!

[@ExiledGypsy]

CCC as proposed by Penrose,surley.

[@leonardofontenelle3560]

IIRC it's not so much the pulsars which distortion was measured, but the distance between them

[@parzh]

4:40 Or Fahrenheit, for that matter :)

[@shanetroy111]

Vocal fry strong in last guy.

[@DrPreetiSahu]

amazing bhaina :)

[@debabratapramanik3719]

Swagat Bhai. Brilliantly explained :)

[@shikhanshu]

Loved the confident and crystal clear explanations from Swagat. Need more folks like him here! In my mind, understanding why and how universe exists is THE most important goal of humankind. Evolution's sole objective is to give rise to creatures that can ask these questions and solve the ultimate mystery. I have the deepest respect for astrophysicists (both theoretical and experimental) who are carrying on this lofty goal.

[@reidflemingworldstoughestm1394]

It's good to be the physicist.

[@ChrisFEJackson]

I wonder what Sir Fred Hoyle would have made about this, or Halton Arp

[@AkshyaMishra-v8d]

Congrats

[@thedeadman8361]

Nice to see some new Scientists on the channel!

[@F1.4the-moment]

Ugh, first….i guess 🙄😜 Thank you for educating me and reminding me why I can be in awe of the universe. Keep up the fantastic work you do.

[@johnqpublic2718]

You guessed incorrectly.

[@OmnipotentO]

reality is wobbly !!

[@declanclarke6929]

This is a great video. Real physics news.

[@chillphil967]

i like the new guys 👍 keep ‘the videos coming! 😇

[@DwainDwight]

best channel on yt

[@SolaceEasy]

If the background waves are still coming at us, does that infer that the universe has always been infinite; i.e.: it is EVERY distance from the edge.

[@Steelrat1994]

No. Even if the universe is finite, there shouldn't be an 'Edge'. That goes against everything we know about the universe. A wave can travel forever even if the universe is finite. Imagine you have a sphere. Imagine an ant running straight at the surface of your sphere. He will be able to run forward forever without reaching an end, but the sphere is finite.

[@adaml2987]

love the blinds in the backround.

[@IIRemy]

my favorite Brady Haran channel

[@christiansmith-of7dt]

A hanging offense

[@cmhiekses]

The text is giant and distracting

[@TheWayOfRespectAndKindness]

Time waves.