Lecture 11

Life in the Universe

 

  1. Are we alone?

 

 

 

    1. No evidence for aliens on Earth (really!).

 

 

 

 

 

    1. No evidence for other intelligent life in the Solar System.

 

 

 

 

 

 

  1. Possible locations in the Solar System where life did exist or can exist now.

 

 

 

    1. Oceans of Europa and Ganymede (moons of Jupiter)

 

 

 

 

    1. Mars (in the past)

 

 

 

 

    1. Atmospheres of Jupiter and Saturn (may be too diluted)

 

 

 

 

    1. Titan and Triton (may be too cold)

 

 

 

 

 

  1. Life elsewhere in the Universe will be harder to detect because of great distances and time delays.

 

 

 

 

 

 

 

  1. Chemistry of life

 

 

 

 

    1. Need solvents, like water.  Other solvents possible like ammonia or alcohol

 

 

 

 

 

    1. Carbon.  Silicon?

 

 

 

 

 

    1. Organic molecules (DNA)

 

 

 

 

 

    1. Miller-Urey experiment

 

 

 

 

 

 

  1. Communication with aliens

 

 

 

 

 

    1. How to do it?

 

 

i.         Send E&M signals (optical expensive)

 

 

 

 

 

j.        “Listen” for signals.  In what band?

 

 

  1. Space travel

 

 

 

 

 

    1. Our spaceships are slow: travel to nearest stars would take tens of thousands of years.

 

 

 

 

 

    1. Space travel would have to be “generational” with the aim of colonizing other parts of the Milky Way.