Astronomy Week 13

This was the last lecture, and it was all about interstellar travel (with a brief review at the end).

Learning outcomes for week 13:

By the end of this lesson, students should be able to explain the following to a general audience:

  • The challenges for interstellar travel
  • Design ideas for interstellar spacecraft
  • The basics of relativity
  • The Fermi Paradox

We again started with a review Kahoot of the worst 5 questions on the week 12 quiz. This time to make it more exciting, I gave $10 gift cards as prizes to 1st and 5th place (just randomly because I can!).

After doing a brief review of week 12 material, we started talking about the challenges of interstellar travel. The big ones being the distances we’d need to travel, the natural speed-limit imposed by the speed of light, the cost of energy, and the mass of fuel needed (for rockets, anyway).

We then did an overview of the different designs for spacecraft to overcome these obstacles: Nuclear rockets, bomb pushes, fusion rockets, ion engines, solar sails, arks, matter-antimatter annihilation, and interstellar ramjets.

We briefly talked about some issues that arise with special relativity if we could get close to the speed of light (time dilation, length contraction, mass increase). A couple great way to possible get around these is to not travel in space at all – but in hyperspace.

Yes, this is where the fun begins! We talked about using black holes, wormholes and warp-drive for space travel. Awesome!

We ended the course by looking at the possible solutions to the Fermi Paradox (“So, where is everybody?”) that is brought up by two very opposing ideas: 1) we know us and Earth are not special and there should be many planets with intelligent life and 2) we haven’t seen any evidence for that to be true.

The possible solutions?

  1. We are alone
  2. There are civilizations but they haven’t colonized for some reason
    1. There are technology issues
    2. There are social issues
    3. Civilizations tend to self-destruct
  3. There is a Galactic civilization but they are purposely hiding from us.

What a great topic and discussion to end on! I wish we had way more time to get into it further, especially since many students are in the Social Sciences.

Finally, I gave a brief overview of the whole course, focuses on the key points we learned. I ended by sharing the idea that even though the course was all about finding life on other planets, it was really about learning more about ourselves.

Their in-class assignment was to write a reflection about their learning and they have been amazing to read. I may post some here just to share!

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