At the limits of astrophysics – with Katy Clough

Why does modern astronomy often sound like science fiction? And how do objects like supermassive black holes, wormholes and warp drives fit into our current understanding of physics?

This event was recorded at the Royal Institution on 23 March 2023.

Much of modern astronomy sounds a lot like science fiction - gravitational ripples in the fabric of spacetime, supermassive black holes hiding at the centre of galaxies, habitable exoplanets within the reach of our telescopes…are there any limits to what is out there?

Whilst largely considered to be firmly in the category of fiction, such concepts are nevertheless based on solid scientific ideas about the curvature of spacetime from Einstein’s theory of general relativity. This theory is known to be hugely counter-intuitive, giving rise to singularities, event horizons and time dilation around black holes. In strong gravity regimes things behave very differently to the low gravity environment on the Earth, so our intuition, which is based on our everyday experience, can mislead us. Studying these objects can help us to challenge our understanding of what is “natural”, and better understand the extreme limits of gravitational theory.

Katy Clough is a lecturer and Ernest Rutherford Fellow in the School of Mathematical Sciences at Queen Mary University of London. She studies systems with strong dynamical gravity using numerical simulations, including black holes and the early universe. She is part of the fundamental physics working group for the future space based gravitational wave detector, LISA. Katy’s first degree was in Engineering and her degree in Physics was obtained from the Open University whilst working as a chartered accountant. After her PhD at King’s College London she worked in Goettingen in Germany and in Oxford University in postdoctoral positions. She believes that science is for everyone and that there is no right way to be a scientist.

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[rbee]

Every so often, I hear a discussion of this level and somehow it brings me an even higher level of enlightenment, curiosity, and inspiration! Amazing presentation, delivery, and insight. I agree with you wholeheartedly in your interpretation. Considering gravity as a force absolutely limited my thought and I hadn't even realized it before hearing you! Don't you worry...I am confident it will catch on very soon. Thank you SO much! All the love and appreciation to you Katy! This completely changed my way of viewing even the things I already knew. I wish you much success and discovery.

[tormodguldvog]

She is one of the best lecturers I have seen in a very long time. She is so cheerful and explains difficult concepts so easily. Captivating and well done!

[Syntax]

Lately, have been delving into learning more about astrophysics/quantum mechanics - and the RI impresses with every presentation. The lecture format with live demos always manages to offer alternative representations which has influenced my understanding across the videos. Coming from a classical maths background, I particularly enjoyed this one!

Thank you for all the hard work putting this together! I still love you Newton ☺

[georgeangles]

There is no limit to how long I'd be able to listen to this woman speak. She's great💪💪

[_eduardolps_.]

She's a splendidly captivating lecturer. I would move to the UK just to hear her speeches on this matter. BTW, knowing not only Astrophysics' possibilities but also its limits is a wonderful way to acknowledge the place of science in our society. Could it possibly solve all of our problems? I hope to cherish new "Katys" Clough in action

[davidschneide]

Chandrasekhar left the U.K. for the U.S. in hopes of finding less racism. Amusing.

[davetubervid]

Brilliant. I usually give up on these types of videos well before the end because I simply can't follow them. I am fascinated by cosmology but totally out of my depth with physics and mathematics. (yes, I am a humanities graduate for my sins). This however was totally understandable, partly due to the brilliant teaching style and personality of Katie Clough, and indeed the whole approach of other lectures in this RI series.

[mariam_tigress]

I love how nonchalantly she talks about time space - like, we can fold it, no problem, it's punching through that is difficult

[JoimFormula]

Kip Thorne should be credited for the accurate black hole visualization in Interstellar movie

[Vile_Entity_]

A lecturer that explains things in laymen’s terms. Give her a bigger chunk of taxpayers money (raise)

[real_DrDummkopf]

As many of these I've seen as well as world science festival I've never actually explored the comments area of it and it paints a better picture other than just trying to get my own understanding. Thanks a million

[MTSVW]

This is the first time I’ve heard gravity explained as a product of curved time in a way that makes sense. I love the analogy of two people hiking north and meeting at the North Pole, and it looking like a force pushing them together even though it really isn’t.

[SimonDallender]

This woman is entertaining, insightful and informative. I’m going to find more of her stuff now. Thank you YouTube and thank you RI!! And Thank you Katy Clough!

[toma]

A very enjoyable and practical lecture. I encourage more lectures like this.

[abdessamadhasnaoui]

I loved the lecture.. Thank you for explaining these valuable things
And thanks to Thé Royal Institution for making these lectures accessible for free
And know that you researchers are and will be forever the best people thar have ever existed😃😃😃

[bilinguru]

The universe is not expanding, but curving in the time direction. Love it! First time to hear it expressed this way, and it really helped me visualize what's going on.

[NeonVisual]

I see gravity as a curvature of causality. Matter has a causal relationship with other matter such as quantum fields interacting, molecular structure, and the more matter there is clumped together, the more complex interactions arise. For example on planetary scales like Earth we get really complex interacting systems like weather, plate tectonics and even life.

It seems that the more matter is clumped together, the harder the universe has to work to allow all those interactions to take place, analogous to a really complex 3D simulation in a computer. In that analogy a computer's rendered framerate may drop as the rendering becomes more complex.

I believe something similar is happening in the universe, and so to maintain causality and and the constant speed of light at which those interactions occur, the metric which has to bend is the rate at which time flows. For you sitting near a black hole's event horizon time appears to be flowing normally as you're next to an extremely compact clump of matter, but for everyone else it looks like time has slowed down for you, again the lowered framerate analogy. Causality has become curved the closer to the clumped matter.

So I think if the universe didn't do this, then the only other metric which nature could alter is to increase the speed of light near clumped matter like overclocking the computer, but this would create causality paradoxes, and obviously this isn't what we observe. Furthermore, particles which don't have mass can't create complex interactions like regular matter, and so they don't curve spacetime at all, but are still affected by the slowdown in causality near matter and so are apparently bent by gravity.

So, gravity is in essence the apparent local reduction of the rate of causality relative to flat spacetime in the presence of complexly interacting baryonic particles.

[andreadelucia]

Such a wonderful and pleasant explanation, very kind, nice and professional at the same time. Thank you so much

[ahsanmohammed]

23:00
An astrophysicist saying, “I've got no sense of distance, ” sounds a bit off to a layman like me.

[rem]

Incredibly gifted and engaging speaker.