Elizabeth J McGrath’s presentation last night of “Using Distant Galaxies as Cosmic Time Machines” was very interesting, especially as a student who has never studied astronomy or physics. She began her presentation with a large photo of galaxies combined together which was not only beautiful but also a nice way to begin talking about the big picture. Although I do not have a strong interest in astronomy (mainly because I find it too big of a concept to grasp my head around), I still learned a large amount of information last night.
One student asked if she ever became frustrated working with such concepts that were so out of her hands and so far away. Of course, she was not frustrated with this, or else she never would have entered the field, but I thought that was interesting because that is an issue I have with learning about space. It is too far away and large for me to wrap my head around so I often get frustrated and overwhelmed with the information I am learning. However, I thought Elizabeth J McGrath did a great job of breaking down concepts for me to understand.
For starters, I did not know what galaxies were made of, so learning that galaxies are made of ordinary matter, dark matter, and dark energy was enlightening. I also thought it was interesting that relative quantities of dark matter and dark energy affect predictions for the growth of galaxies and large scale structure in the Universe. Speaking of growth of galaxies, the color implication was also fascinating. I had no idea that the color of a galaxy actually implies the age of that galaxy, for instance blue stars live short lives, so that galaxy would be relatively young, as opposed to red stars which live long lives, which would be an older galaxy. This color differentiation was especially interesting when relating it back to the first photo she showed us at the beginning of the presentation, which she then showed again, so we could actually see which galaxies were older and which were younger.
The information she shared about light speed was incredibly interesting. I knew that it took 8 minutes for the light from the sun to get to us, but I had no idea that light takes 4 years from closest star (other than the sun), 27,000 years from center of our galaxy, and 2.5 million years from another galaxy (Andromeda Galaxy). This timescale is crazy, but also so fascinating when thinking about “looking back in time”. When I think of a “time machine” I think of a crazy scientist making a machine to go into the future or past, when in reality by looking at other galaxies we are using a Time Machine. When thinking about the presence of the past, looking at distant galaxies is doing exactly that, because by the time the light travels to Earth it is far in the past. I thought this was a very unique way of thinking about the presence of the past and an especially interesting way to wrap up all of these lectures.