We discussed Week 2 of “Philosophy and the Sciences: Introduction to the Philosophy of Physical Sciences” the course from Edinburgh University. We tried to track the journey from a steady state theory of the universe through to the big bang theory, and how we know the universe is expanding. We had dipped into Thomas Hertog’s book on Hawking’s final theory of time, and were taken with the idea that Georges Lemaitre who suspected this and persuaded Einstein not to remove the cosmological constant from his equation, because it could represent the rate of expansion - was a catholic priest!. When the red shift in the light from other galaxies was measured, it was put down to the Doppler effect - they are moving away - and if more red shift means higher velocity and the galaxies are further away, the universe would appear to be expanding and any steady state theory is falsified. However, gravity should be sufficiently strong to hold the universe together, so dark energy is postulated to counter this and push them apart. Then again, the galaxies themselves are not expanding, just the space in between, and we need dark matter to keep them from spreading. Add to this that in order for us to even exist, the universe had to expand then take a rest then expand again, and there is room to speculate on the underdetermination problem here, and this will be addressed in Week 3 of the course.