Professor McGrath’s lecture on the depths of space was completely fascinating and entirely captivating. She immediately jumped into the exciting world of space on her first slide; the background photo included tens of thousands of galaxies in just one picture. The entire image was lit up with vibrant colors and uniquely shaped designs. At first glance, I thought everything in the picture was a distant star or far off planet. However, Professor McGrath explained that it was a composite image of various telescopes that encapsulated thousands of far away galaxies; she told us that it took decades to put together and I was completely amazed. She went on to talk about all the different types of galaxies, explaining how scientists classify them based on certain properties like shape, age, etc. Professor McGrath furthered explained how galaxy evolution occurs on a timescale of up to one billion years! My ears immediately perked when I heard this fact; I thought to myself how on Earth can anyone study these evolutions? Thankfully, my confusion was short-lived as Professor McGrath revealed her profession’s secret: time travel! At this point, I am completely enthralled in everything Professor McGrath had to had and could barely find the time to look at my computer to take notes. However, I did manage to capturing some information that I found staggering. I learned that light travels at a finite speed of 300,000 kilometers per second; and henceforth, the time it takes for light from the moon to reach the Earth is one second. The time it takes for the Sun’s light to reach the Earth is eight minutes, and the equivalent statistic to the center of our galaxy is 27,000 years! All of this information was just meant to emphasize the fact that Professor McGrath and her coworkers work with materials and information that occurs in the past. Every piece of data recorded is reaching us for the first time and could be dated back centuries. Things seemed to get even more complicated when Professor McGrath mentioned the implications and effects of dark matter, unseen particles with gravitational influence. Yet, despite the obvious confusions in the field of space study, Professor McGrath mentioned several easy indications and hints for space study. For example, if looking into a telescope, you can conclude that the massive, blue stars live short lives and are relatively young while the low-mass, red stars live much longer with a greatly extend life cycle. Professor McGrath futher explained how the difference in color, design, structure, and content infers that there must be forms of evolution going on with these galaxies. Professor McGrath illustrated how her interest lies in the transition period, or the very beginning of the red star sequence. For people in her field, they must ask themselves what is the process that is moving the galaxies from blue cloud into red sphere? She disclosed leadings theories like black hole feedback, halo quenching, morphological quenching, all of which were ideas well beyond my pay grade. She explained how they know the cosmology (ingredients) of these galaxies, though the theory (recipe) needs more observational constraints as there is no single path to becoming a massive, quiescent galaxy. I asked if Professor McGrath ever gets frustrated with studying materials and information that is millions of miles away, “out of sight and out of mind”, quite literally. She responded, however, by saying that it was the reason she got into the field in the first place. She is fascinated by the neverending study and constant flow of information, which now, I must admit is what makes studying space and the world beyond Earth so special.
Looking at the Past in the Present
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.