It’s more than once that I’ve heard Neil deGrasse Tyson say something along the lines of “nothing worse than people who know enough to think that they’re right but not enough to actually be right”. This famed astrophysicist is quite defensive of knowledge and at times comes across as being the only one out there who has any of it. But I get his point. These days it’s easy for anyone to read about anything to any depth. Whether it came from your uncle who shared a post on Facebook (likely shallow and questionable) or from a scholarly research paper, cited and reviewed, posted on a .edu website (likely a good source).
I admit that I probably fall somewhere in the middle of these. I am careful to do my research, but I am not a researcher nor an academic. I’m a teacher, a generalist with a slant towards astronomy. So I know some things, and there are things I’m still and always learning about.
However, regardless of where I fall on the knowledge continuum, the fact that I teach astronomy always sparks conversation and questions. I love those situations where somebody asks me about space or something they saw or something they watched. It means other people are always learning and curious too and it’s good to encourage those things, isn’t it?
Recently, I was the guest on a podcast and the host asked me a question that put me on the spot! He wanted me to blow his mind with something that he would never have known about space. This was my chance to stretch my “galactic” legs, but I think what happened is I stumbled out of that gate and never really got my momentum going. I guess I was caught off guard and the only thing that came to mind was the comet Shoemaker-Levy.
It was this comet that got a lot of attention in 1994 as the one that broke apart into 18 or 20 pieces, rounded the “corner” of the Sun and plummeted headlong into Jupiter. It was at a time when NASA had just got the Hubble Space Telescope up and running and this was going to be one of it’s first assignments. Astronomers would use the best sensing tool they had and watch a planet get hit by a comet!
By being a firsthand witness, NASA was able to learn more about the atmosphere of Jupiter, what it was made of, and various other measurements about the dynamics of a solar system. Remarkably, perhaps the most stunning thing was that the impact sites were each 2-3 times the size of Earth! It got scientists at NASA thinking that had Earth been the target of this comet, life would have been annihilated. This is what we call an extinction level event (an ELE, of which there have been likely 5 in the history of Earth) and it precipitated the Near Earth Object program at NASA to go on the hunt for other such potential impactors.
Now that may have been a decent answer to the “blow my mind” question, but I could have done better. I may have saved it a bit by expanding on the idea of gravity tractoring. This is the concept of putting a heavy orbiter alongside a potentially hazardous asteroid or comet in order to use gravity to tug it off course and miss Earth. So tagging that onto the end of my answer may have helped me get the win, but still, I wasn’t totally happy with what I came up with. Perhaps it was that I knew enough to sound like I knew what I was talking about, but not enough to be an authority. If that was the case, my apologies to NDT! (He hates that stuff).
So what would have been an answer that I’d have been happy with? Well, I love explaining the difference between Newton’s explanation of gravity compared to Einstein’s theory of general relativity. Are we sitting in our chair because gravity is pulling us into it (Newton) or are we sitting in our chair because gravity is pushing us into it (Einstein)? That is a fascinating story, especially since Newton came up with it during a time of social distancing due to a pandemic!
Or I would have been happy with explaining how we know the age of the universe based on two spectacular discoveries of the 20th century (redshift and cosmic background radiation). What is most compelling to me is that the universe is approximately 14 billion years old while the Earth is approximately 4.5 billion years old. So if we are to measure the age of the universe using a unit of time called a year, and year is the time it takes for Earth to orbit the Sun, then we were measuring time for about 9 billion years using a “clock” that didn’t exist!
And another example I would have been happier with is the idea of special relativity. So for example, I could use my telescope and view Andromeda, our nearest galactic neighbour approximately 2 million light years away. If I could talk to a photon of light that I capture in my telescope, I could ask it how the trip was and what it was like to hurtle across the cosmos at the speed of light for 2 million years! But I know that the bizarre answer the photon would give me is that as far as it was concerned, it just left! This is because for an object in motion at or near the speed of light, time is inconsequential. The observer would have aged 2 million years, but the moving object would not. That is essentially Einstein's theory of special relativity.
Alas, I didn’t think of those things when my host asked me the question. Well, you know how it is, right? How often have you said after an argument “if only I said ……”. Historically, I’ve heard it said that Winston Churchill never lacked for words in any conversation. Now, is that actually true? I don’t know, I just read it on a Facebook post.
The podcast I’m referring to is called Lasting Learning and the host is Dave Schmittou. Dave hosts excellent conversations about teaching and education and is inspiring whether you’re a teacher or not. I’ll post my episode when it comes out October 6th.