Speaker John Waterhouse - Are We Alone in the Universe?

By following quite a lot of maths John showed how the accepted wisdom is that there is unlikely to be intelligent life as we know it in our galaxy. This was based on the facts that earth is in a sweet spot in relation to many other planets in being just the right distance from a star that is not too big or too small, has a reasonably sized moon and is not in the way of a lot of space debris and it has a good magnetic field around it.

He did feel, however, that since there are as many galaxies as there are stars in our galaxy it is likely that other planets will exist in the universe that have similar properties to earth. However, they are so far distant that we will never be able to communicate with any intelligent life that might have developed.

His notes from the talk are shown below: -

Are we alone in the Universe?                    Zoom talk to Blaize. 24.03.2021
1. We being “intelligent life”
2. Vote. Those agree that we are alone?
3. Have we heard from anybody? No. Wow! LGM. UFOs?  ………..No!
    Have we looked and listened? Time – yes for 100 years. SETI.
    Distance. 4 years, 27,000 years, 2.5 million years.
4. But we are here, that much we know. Why here? Why the Earth? Might there be another “Earth”? Can we find it? What is special about it?
5. Where are we? - In a galaxy between the spiral arms – quiet spot?
6. Prof Brad Gibson, University of Hull. Life = (ingredients + an oven + cooking time).
7. Cooking time:     Earth circa 4.6 bn years. Life evolved here: Took 1bn yr for single cell, 2bn yr for multicell, last 200m mammals, last 200,000 years Homo Sapiens.    So a tiny window. 0.04%.
8. Basic Ingredients:
     a) carbon           friendly, receptive, common allowing complex molecules
     b) water             wonderful solvent, freezes on top, needs temp just right – goldilocks - habitable zone, distance from our star, the sun, only one in our SS. -    10% of planets?
     c) star too big?            More massive stars burn quicker. So less then 2 SM
     d) star too small?        Planets nearer and flares, radiation. So more than ½ SM So not all stars. Maybe 10% of stars?
    e) radiation          E protected by magnetic field. Maybe 10% of planets?
     f) moon         Our moon is large (0.01 relative to E), much larger than any other we know (200). Formed 4.5bn yrs. Long-term stability, climate.
    g) planets?    Found c6,000 etps in c1,000 SSs. Do look very different, ps are smaller and closer to their Ss. But small sample!
   h) Collisions?    Comets from Oort Cloud. 65m yr ago. In 1m years a star will enter the OC, creating perhaps 10m comets!
     i)    Explosions?  SNe.  1987, 170,000 lyr away. Betelguese is nearest candidate at 450 lyr.   But >50 ly is OK.
     j) Sun gets hotter?  500m years it will be 60/70C on E, boil off oceans. We will have had to evacuate or go subterranean.
So rocky planet, stable and avoiding SNe! Ideal position in our G.

9. 100 bn stars in our MW galaxy, (maybe 400 bn !) ie 100,000 millions.
      10% right sort of star                                      10bn
      10% in right place in our G                                1bn
       50% have planets                                                500m
       10% rocky in HZ                                                   50m
       10% have magnetic field                                     5m
        10% stabilizing moon                                      500,000                500
So maybe 100,000 develop life of some sort? Optimistically?
Pessimistically 500!
         10% intelligent life                                                50,000           50
          10% communicating society                                5,000              5
But will we ever communicate?    We have had radio for only c100 years?
How long does a communicating society last? Say 20,000 years? How many right now? Say starting 5bn years ago, to now. 20,000 years is only about 0.01%.
So 5,000 becomes 5!!    Or pessimistically a lot less than ! Want to believe!
Where will we first find any life?    Moons of Jupiter and Saturn? Europa and Enceladus. Not surface, underground lakes?
Have we already seeded it? Crashed lander on moon with tardigrades! No H&S risk assessment!                                                  JRW           24.03.2021