The Exoplanet Revolution - Professor Didier Queloz, University of Cambridge

Until recently, the solar system provided the only basis for our knowledge of planets and life in the Universe. In 1995 Didier Queloz and Michel Mayor dramatically changed this view with their discovery of the first giant planet outside our solar system. This spawned a revolution in astronomy, both in terms of new instrumentation and in our understanding of planet formation and evolution. Planets outside our solar system, orbiting other stars, are called exoplanets. Thousands of exoplanets have been identified over the last three decades, ranging from large planets like Jupiter to smaller denser objects like the Earth. The diversity and prolific quantity of these discoveries has revolutionised our understanding of the nature and formation of planets, opening up a surprising new perspective on the possible rarity of planetary systems similar to our own. It has also raised exciting prospects for the potential to probe planetary atmospheres for traces of life.
Didier Queloz is Professor of Physics at the Cavendish Laboratory in Cambridge and Professor of Astronomy at the University of Geneva. His research focuses on the detection and measurement of exoplanet systems, aiming to retrieve information about their physical structure and to better understand their formation and evolution, by comparison with our solar system. More recently he has worked on the detection of Earth-like planets and life in the Universe. In 2019 he received the Nobel Prize in Physics for his research and discoveries. At Cambridge he leads a research program with the goal of making further progress in our understanding of the formation, structure, and habitability of exoplanets in the Universe, as well as to promote and share the excitement of this work with the public.

[@nellwhiteside3042]

Thank you. I have learned a great deal. Life is chemistry - not magic, although it is still magic.

[@Neilhuny]

Absolutely fascinating lecture! Very thought provoking.
I fall in to the extremely sceptical view of the possibility of finding life elsewhere. Merely to get multicellular life is very nearly impossible - even on the galactic scale of probability, imo. To then progress further the only model we have that permits progress requires that we have mass extinctions at very specific points to clear the way for explosions of new life forms.
I think single cell life exists often and will be found soon. Multicellular life may not be found, ever. Advanced life forms like vascular plants or chordate animals will not exist elsewhere. Technological life forms occur once in the universe - we are alone

[@robertbeattie1061]

Agreed

[@pbkobold]

Evolution of a eukaryotic cell is the Great Filter.

[@a.karley4672]

"Merely to get multicellular life is very nearly impossible - even on the galactic scale of probability, imo" Do you have any evidence to support this otherwise unsupported opinion?
I look at the existence of life in at least one place in the universe as evidence that it isn't ridiculously difficult to get life going - at least on rocky planets with an abundance of at least one solvent (water, in our case, and that is probably the commonest - but I'm not going to rule out ammonia or ammonia-water mixtures ; methane and CO2 imply far lower temperatures and hence reaction rates). Which are anticipated to be quite common, given the numbers of planets found, and the self-evident biases in planet discovery.
Regarding your (and @pbkobold 's) opinion to the effect that "Evolution of a eukaryotic cell is the Great Filter." - Again I cite evidence from Earth history that it's not that difficult to do. Current opinion is that at least *THREE* times in Earth history an event of enodosymbiosis has succeeded - resulting in chloroplasts, mitochondria, and nitrogen-fixing "nitrosome" organelles (recently announced).
Actually, the announcement of that last one prompted me to dig out an old book by Lynn Margulis, where she suggested that almost ALL the organelles of eukaryotic cell were formed by successive episodes of endosymbiosis. I think that she actually predicted that "nitrosome", but I need to check.
I was sceptical of her repeated re-use of the endosymbiosis card, but it seems that she has had another (posthumous?) success with her "big idea". That should be thought-provoking.
You may be right in your speculation that "simple" life is common, but "complex" life rare. You've probably heard of Simon Conway-Morris and his book "Life's Solution: Inevitable Humans in a Lonely Universe" ; if not, you may find it interesting. But beware - despite being an excellent palaeontologist, when he gets away from the rocks, he lets his writing be tainted by the stench of supernaturalism.
Personally, I suspect - hope, I grant - that a high proportion of Earth-like planets (and potentially a considerable number of "icy moons") could be hosting their own separate origins of life, not necessarily all water-based. We have a handful of possible sites in the solar system, which are the target of exploration proposals and funding fights. Outside the Solar system, we'll just have to send our robots and genetic material "on ice". Do-able, but slow.

[@Neilhuny]

​@@a.karley4672 Great reply, thank-you.
"Merely to get multicellular life is very nearly impossible - even on the galactic scale of probability, imo" Do you have any evidence to support this otherwise unsupported opinion?
Eukaryotes appeared ~1.65 billion years ago, Earth is about 4.54 billion years. Scientific evidence suggests that life began at least 3.5 billion years ago. So, for ~1.9 billion years billions of Archaea reproduced billions upon billions of times (daily?) and nothing much changed. Then a bacterium and an Archaea got together and added sexual reproduction to their characteristics. Probably a 2nd merging occurred with a cyanobacterium. Three merges occurred. OK. People quote stars in the galaxy, galaxies in the visible universe and say so many billions of opportunities surely means life exists elsewhere in the universe.
Why?
Billions upon billions of bacteria-archaea-cyanobacteria interactions are happening constantly, have happened for billions of years, one eating the other. Eukaryotes happened once. (some claim more). Those billions upon billions exceed the number of stars/planets imo. Then we must have extinction events to allow expansion of new lifeforms at the right points in evolution, so far as we know.
The odds are too extreme for anything more than slime to occur ... (the most basic life forms)
However, I haven't read either the Lynn Margulis book or the Simon Conway-Morris book "Life's Solution: Inevitable Humans in a Lonely Universe". I shall genuinely find copies today and read them - they sound great!

[@Neilhuny]

Frigging hell! - £64 on Amazon for the Simon Conway-Morris book!
£4 for an Kindle version of Lynn Margulis "Symbiotic Planet: A New Look At Evolution" or £11 for a paperback. I shall look for a better price.
You may be able to make an extremely good profit for a 2nd hand copy of the Conway-Morris book