The overall concept of a black hole is the idea of “Trapping”, some can enter the black hole but cannot escape. Black holes exist due to gravity. Gravity is a universal force that makes everything attract everything else. If you put a lot of masses within the same region, then they will be pulled in from the attraction of a different mass, creating a black hole. The story of the black hole went through 4 iterations.
– Newton’s Law of Gravitation
– Newton’s Law of Motion
– In 1783 John Mitchell used Newton’s principles to come up with the idea of a dark star
– This came to a dead end because it isn’t considered a black hole due to Newton’s laws state that things can escape rather (not a black hole)
– Albert Einstein’s Theory of General Relativity in 1915
– General relativity is a consistent theory on its own, and this theory predicts the existence of black holes which trap anything that falls into them.
– Stephen Hawkings in 1975 still uses the idea of general relativity but adds the thought of quantum theory.
– a problem that comes up is the black hole paradox
– in this third iteration, we find that mass (or equivalently, energy) is not trapped, while information is either lost or trapped, depending on our assumptions about the endpoint of black hole evaporation.
– Gravity is described by a quantum theory of spacetime
– Matter is described by quantum theory as well
– the hole takes the form of a fuzzball, which traps neither energy nor information
I vaguely knew what a black hole was; a dense tiny ball of what I thought was anti-matter? It doesn’t seem terribly relevant because Dr. Mathur did an incredible job of breaking this incredibly difficult physics concept down to something that made sense to someone who has NEVER taken a physics class…
I found it really interesting that there was so much progress made on the topic of black holes by just one person. Though I did have a vague idea of what a black hole was, I had zero clue that this was the topic of Hawking’s research, and what presumably made him so famous. The man is more brilliant than I even thought – I was looking through the book he wrote with a colleague and my head hurt just looking at the calculations. It is so crazy to me that an actual human mind came up with this theory and had enough mathematical evidence to publish it. I imagine the feeling I had reading his book is comparable to the feeling that people had reading Newton’s book a couple centuries ago!
Another bit I found intriguing during Dr. Mathur’s talk was string theory. He briefly summed it up, but it kind of caught me off guard that he was teaching every bit of Hawking’s work and discussed how incredible it was that he had this breakthrough, but Dr. Mathur doesn’t believe it himself! How crazy is that? I found that maybe the emphasis was more on how genius Hawking truly was, not that scientists today are trying to prove him wrong.
I would love to visit the spot Hawking walked along on the river, maybe I can channel some of his genius for my midterm after break… (haha)
Since I was unable to attend the lecture, I read “What is a Black Hole”. I have zero background information on black holes, so this reading was very interesting. The first description of black holes using Newton’s law made sense and was easy to follow. The second description using Einstein’s theories was slightly more difficult to comprehend. In order to even begin to understand the third or fourth descriptions, I had to read them multiple times and look at the quiz. I still could not not explain them, but I could explain the issues with Hawking’s description and how the fuzzball theory remedied that problem. As I looked at the images that accompanied each description, I noticed that Einstein’s image looked familiar. I found it interesting that in popular media (movies/tv shows), Einstein’s theory of the black hole is used as a depiction, despite being disproved. I wonder if this is because it looks cool and is easier for the general public to understand (compared to the current fuzzball theory) or if there is simply a lack of knowledge in those who create science fiction works.
While the subject of Dr. Mathur’s lecture was beyond me, I really appreciated how he chose to make the lecture interactive by asking us questions and leading us to figure out the answers to some of these seemingly unreachable conclusions. It made the material easier to follow step-by-step and his visual representations helped as well (although there was still a bit I didn’t fully grasp of course). It was interesting that as Dr. Mathur said, we only needed “high school physics” in order to understand everything in his lecture. A subject that seems so unreachable and complex, when actually thought about in individual components, can really be explained somewhat simply, or with basic knowledge. I think that we learn about certain principles in classes, or in high school especially, but we don’t always see how they have applications currently in research, or in very complex research. So what I learned from this lecture, generally, is that sometimes the answer to a very complicated problem is really quite simply explained.
Dr. Mathur’s talk was very fascinating. I was first introduced to Stephen Hawking when I read selected chapters from his book “Black holes and Baby Universes and Other Essays”. I was so fascinated by his ideas about black holes. Dr. Mathur was able to explain black holes in a way his audience would understand. As Hawking is a little hard to understand at times, I really appreciated his talk. Another book I read by Hawking that is fascinating and I recommend everyone read is “Brief Answers to the Big Questions” published after his death. In it, he attempts to answer many of the questions humans and science have about the universe. It is divided into Why are we here? Will we survive? Will technology save us or destroy us? and How can we thrive?. In it he goes into the mechanics of black holes. I guess that is his way of defending his theory. Form Dr Mathur’s lecture, String Theory attempts to invalidate black holes and present a different solution. Because physics can’t have infinity as a solution.
To me, Dr. Mathur’s ability to so clearly and concisely explain astrophysics concepts was almost more amazing than the subject matter itself. I’ve known generally what a black hole is and that Stephen Hawking became well known in part due to his work on them, but why there might be black holes, how they functioned, and what Stephen Hawking’s research on them was weren’t questions I had thought much of. If I had, I probably would have assumed that these things would be completely beyond my understanding before Dr. Mathur’s lecture.
Dr. Mathur suggested that a “string star” model would work better at explaining how black holes work than Hawking’s model, where density could be infinite within a black hole’s event horizon anwhere, with a small enough radius and strong enough gravity, new particles could “pop” into existence. Whether they end up being true or not, these hypotheses were pretty fascinating to me.
I really enjoyed Dr. Mathur’s talk! I’m really glad he focused on black holes during his lecture because I’ve always been fascinated by the topic. I didn’t even realize that Stephen Hawking’s work revolved around understanding black holes better. The way that Dr. Mathur presented the information was very digestible, even though the concept can be hard to understand at first. His lecture reminded me of reading about different scientific discoveries in “A Short History of Nearly Everything” by Bill Bryson.
I appreciated that Dr. Mathur began the lecture by describing exactly what a black hole is and the different research being conducted on black holes leading up to Hawking’s involvement with Roger Penrose. Imaging Hawking walking around the lawns of Cambridge University while thinking about black holes made me want to visit such a historic place. I definitely have a better understanding of Stephen Hawking’s work, Hawking radiation, and the information loss paradox after the lecture.
After seeing Dr. Mathur on the OSU 150 Innovations page, I was very glad that he explained his research to us. I haven’t looked into string theory before, but Dr. Mathur’s description of his work sparked my interest. I was also blown away by his explanation of the photo of the black hole that we discussed in class!
Dr. Mathur’s beginning points about black holes seem so intimidating when compared to life on Earth; it gives perspective on how large the universe is, as well as how powerful some of the elements of the universe are. I like that he touched on each of the varying theories for black holes rather than just saying the theory we now know to be correct. Sharing each of the varying ideas helps visualize how scientists of the time were thinking about this new phenomenon and how they tried to conceptualize it.
One component of his talk that was unfamiliar to me was the concept of Hawking Radiation discovered in 1974. I had still been under the impression that once something passes the horizon of a black hole, it could never come out. It was surprising to learn this was not the case, and that black hole evaporation actually occurs over time. And while the process of this black hole evaporation is extremely slow, it would eventually disappear; based on Hawking’s reasoning. The particles evaporating from the black hole oftentimes are pulled back into the black hole because of the mass that is still left behind, and these particles are finally able to “escape” when they have generated enough energy; this is why this evaporation is such a slow process.
The well-known photo of a black hole can actually be misleading because the light that we observe in the photo is actually objects orbiting the black hole since we cannot see anything past the horizon. Some of the light we see is also the way light is bending over the black hole from the back as it rotates. The light becomes so bent that we can’t actually see what was there before.
Overall, I thought this was one of the most interesting talks in the course thus far. As much as I do enjoy history combined with biology, these types of lectures give the audience a new perspective on the sheer size of the universe surrounding our planet and how it could affect us at some point.
I didn’t realize that Stephen Hawking was most famous for proving that black holes violated the rules of quantum mechanics. Honestly, I only knew that he did work with black holes. I did see the movie The Theory of Everything but that didn’t really outline much.
I also didn’t realize the definition of a star was a bunch of nuclear explosions contained by gravity. The fact that black hole formation actually relies on violations of the Pauli-exclusion principle is something I didn’t expect to be brought up, but makes sense. Black hole formation seems to include so many relatively simple physics and chemistry concepts that come together in a crazy way. I have heard of Hawking radiation but had no idea what it was. I had a huge “OHHH” moment after he did the math and showed what it was. It was so cool!
It’s nice to know that our sun will not become a black hole. I don’t know why that’s comforting to me, but it is.
I found this lecture fascinating because it provided the first comprehensive, clear explanation of black holes that I’d heard and it answered a lot of questions I didn’t know I had! I really enjoyed Dr. Mathur’s presentation style and this presentation gave me a new appreciation for Dr. Hawking’s work. It’s amazing how many questions we still have about the universe, and physics is an excellent example of phenomenon of having more and more questions with each answer we find. I found it interesting that the size of stable stars is limited, meaning that the size of black holes is limited, except there is a supermassive black hole at the center of our galaxy. Where did that supermassive black hole come from? I found it exciting that we don’t have an answer for that yet! I also have a much greater appreciation for the work it took to be able to obtain this image of a black hole. I understand it so much better now, and enjoyed learning about how the light can bend preferentially in one direction vs. the other based on the black hole’s rotation.
Image from https://www.jpl.nasa.gov/edu/news/2019/4/19/how-scientists-captured-the-first-image-of-a-black-hole/