1 / 26

The Hot… The Cold… and the Just Right Living in a Chemically-controlled Cosmos

Explore the evolution of the universe, from the hot and energetic beginnings to the formation of stars and the emergence of complex molecules. Discover how these conditions paved the way for the chemical diversity we see in the cosmos today.

aandrea
Download Presentation

The Hot… The Cold… and the Just Right Living in a Chemically-controlled Cosmos

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Hot… The Cold… and the Just RightLiving in a Chemically-controlled Cosmos Martin McCoustra Institute of Chemical Sciences and Department of Chemistry

  2. The Hot… The Very Hot… A Long Time Ago... 13,800,000,000 Years Ago to be Roughly Correct, A Universe Not Too Far From This One Popped into Existence From the Seething Sea of Energy Came the Forces and Particles that Characterise our Universe As it Cooled, Atoms Were Formed... But only Hydrogen, a Dash of Helium and A Twist of Lithium This Was A Universe Dominated By Physics

  3. The Hot… The Very Hot… Jennifer A Johnson, Ohio State University

  4. The Hot… The Very Hot… • As the Universe cooled… Stars and Galaxies were formed from the elements in the Big Bang Periodic Table • This first generation of stars were really massive… typically more than 100 Solar Masses • These converted some of the light atoms in the early Universe into more useful heavy atoms like oxygen, carbon and nitrogen

  5. The Hot… The Very Hot… Fusion Processes R, S and P Processes • For elements up to Iron, fusion is exothermic • Formation of heavier elements by fusion is endothermic and only occurs in extremely energetic events like supernovae • Neutron (R, S) and Proton (P) capture processes climb the ladder of atomic number from Iron • But need high neutron densities to do so efficiently A Simple S Process Sequence n n n Heavier 56Fe 57Co 59Cu 58Ni Elements    https://en.wikipedia.org/wiki/Stellar_nucleosynthesis

  6. The Hot… The Very Hot… Jennifer A Johnson, Ohio State University

  7. The Hot… The Very Hot… • These huge stars lived short, bright lives and died spectacularly in supernovae explosions that seeded the Universe with heavy, chemically-interesting atoms The control of the evolution of the Universe shifted from the purely physical to the chemical with the birth of the Chemically-controlled Cosmos

  8. Our Eyes on the Cosmos… • As we look out on the Universe today, we see a colourful and diverse environment • The Constellation of Orion illustrates how, even with the naked eye, we can see variations in the colour of stars • These tell us about • Stellar temperatures • Chemical composition • Age

  9. Our Eyes on the Cosmos… • Professionally, our window on to the Universe is not our own eyes, but the eyes of large telescopes such as the VLT, operated by European Southern Observatory, at Paranal in Chile

  10. Our Eyes on the Cosmos… • But more importantly in looking for molecules in space • We use infrared, microwave, millimetre wave and radio telescopes dotted around our planet such as ALMA • We also use space-based observatories working in these spectral windows like Herschel and the James Webb Space Telescope

  11. Horsehead Nebula Triffid Nebula Eagle Nebula 30 Doradus Nebula Our Eyes on the Cosmos… 200+ Molecules Have Been Observed in Space! https://en.wikipedia.org/wiki/List_of_interstellar_and_circumstellar_molecules

  12. The Cold… NGC 3603 W. Brander (JPL/IPAC), E. K. Grebel (University of Washington) and Y. -H. Chu (University of Illinois, Urbana-Champaign) Diffuse ISM Dense Clouds Star and Planet Formation (Conditions for Evolution of Life and Sustaining it) Stellar Evolution and Death

  13. The Cold… • Molecules are crucial for • Maintaining the current rate of star formation • Ensuring the formation of small, long-lived stars such as our own Sun • Seeding the Universe with the chemical potential for life

  14. The Cold… 100 °C The boiling point of water 100 °C 38 °C The highest recorded temperature in the UK (Gravesend, Kent, 2003) 80 °C 60 °C 0 °C The freezing point of water 40 °C 20 °C 3 °C The temperature in your fridge 0 °C -27 °C The lowest recorded temperature in the UK (Braemar, Grampian, 1982). -20 °C -20 °C The temperature in your freezer -40 °C -60 °C -80 °C -60 °C The average temperature on the Martian surface -89 °C The lowest recorder temperature on Earth (Vostok Antarctica, 1983). -100 °C -120 °C -140 °C -160 °C -196 °C The boiling point of liquid nitrogen -180 °C -200 °C -220 °C -240 °C -273 °C Absolute zero -260 °C -263 °C The temperature in interstellar space -280 °C • Complex molecules point to a surprisingly complex chemistry • But what are the conditions this chemistry must operate in? • Low temperatures mean there is no thermal activation of reactions

  15. The Cold… Pressure/mbar 2300 mbar The pressure in your car tyres 1000 mbar Atmospheric pressure 800 mbar The pressure in a vacuum cleaner 300 mbar The pressure at the top of Everest 7 mbar The average pressure on the surface of Mars 0.0001 mbar The pressure in a light bulb 104 10-5 mbar The pressure at the top of our atmosphere 102 1 10-6 mbar The pressure in a TV tube 10-2 910-11 mbar Ultra-high vacuum 10-4 10-15 mbar The pressure in interstellar space 10-6 10-8 10-10 10-12 10-14 10-16 • Complex molecules point to a surprisingly complex chemistry • But what are the conditions this chemistry must operate in? • Low temperatures mean there is no thermal activation of reactions • Low pressures means there is no collisional activation of reactions

  16. The Cold… Adapted from Fraser, McCoustra & Williams, Astronomy and Geophysics, 2002, 43( Issue 2), 210. • The chemistry that we are used to and understand at ambient temperatures and pressures doesn’t work! • Complex molecules point to a surprisingly complex, and efficient, chemistry • Gas phase chemistry involving ion-molecule reactions and some type of reactions involving free radicals go a long way to explain what we see

  17. The Cold… • But ... • Building chemical models of the evolution of gas clouds, including networks of the 1000s of reactions that are likely to occur, still fails to reproduce the observed concentrations of certain simple molecular species such as H2 (the most abundant molecule in the Universe), H2O, ... Astrophysicists invoke chemical reactions occurring on icy dust grains as a means of accounting for the discrepancy between gas-phase only chemical models and observations

  18. The Cold…

  19. The Just Right… • The icy grains, processed by heat, light and charged particles are the building blocks of planets • The ices themselves may even contain the building blocks of life, prebiotic molecules • Incorporated into comets these crucial molecules were likely delivered to the Earth some 4 or 5 billion years ago, seeding it with the potential for life

  20. The Just Right… • How do we know that complex organic molecules were delivered to Earth in this manner? • One particular class of meteorites gives us strong evidence; carbonaceous chondrites such as the Murchison Meteorite are found to be rich in organic matter

  21. The Just Right… • This organic matter can be extracted and analysed and is found to contain the key building blocks of life • More importantly the amino acids were found to be left handed just like the amino acids in terrestrial biochemistry!

  22. The Just Right… • Around 80% of the primordial pre-biotic chemical load is thought to have been exogenously delivered on comets • The balance was probably made in our primordial atmosphere by reactions demonstrated by Miller and Urey in the 1950s • However, even the simple molecules that process needs would have been present in the gas cloud from which our star and planets formed

  23. The Just Right… Biogenic Molecules (Exogenous Delivery and Endogenous Synthesis) + Redox Chemistry (Iron-Sulfur World) + Templated Replication (Clay World and PAH World) https://en.wikipedia.org/wiki/Abiogenesis

  24. The Just Right… • We can make the molecules necessary for life in space, in planetary atmospheres and on planetary surfaces • Additional pre-biotic processes occur on planetary surfaces that integrates specific chemistry • This brings the hardware for potential life to the table • But that’s as far as simple chemistry goes that’s it! • To go further we need to address questions relating to when does autocatalysis and abiotic replication start to carry the information necessary to become biological reproduction

  25. The Just Right… https://en.wikipedia.org/wiki/List_of_exoplanets_discovered_using_the_Kepler_space_telescope The physics and chemistry of star formation, that we model in our laboratories and in our computers, is universal and so the chemical potential for life must be universal

  26. Acknowledgements… Professors David Williams and Serena Viti (UCL) Dr. Mark Collings, Dr. Jerome Lasne John Dever, Rui Chen, Simon Green, John Thrower , Vicky Frankland, Ali Abdulgalil, Demian Marchione, Alex Rosu-Finsen, Skandar Taj and Rushdi Senevirathne Dr. Wendy Brown (Sussex) and her group Dr. Helen Fraser (OU) and her group Professor Nigel Mason (Kent) and his group Professor Tony Parker and Dr. Ian Clark (CLF LSF) ££ EPSRC and STFC Leverhulme Trust University of Nottingham Heriot-Watt University ££

More Related