In graduate school, my advisor introduced us to a particularly vexing fluid dynamical thought experiment known as the Feynman sprinkler. After observing an S-shaped sprinkler that rotated when water shot out its arms, physicist Richard Feynman wondered what would happen if the device were placed in a tank of water with the flow reversed. If the sprinkler was sucking in water, would it rotate and, if so, in what direction? (Image and research credit: K. Wang et al.; via APS Physics)
Read the full article
It was the night before an electrodynamics exam. I was visited by Richard Feynman and Leonard Susskind. I presumed they'd come to help me revise, but Susskind launched into a lecture about string theory, while Feynman kept trying to give me dating advice.
Billions of stars, how many unimaginable worlds ? How do they perceive time and space ? How do they define and express art ? What is love for them ? What drives their pursuit of knowledge and understanding ? What existential questions intrigue them ? I wonder, a lot.
The problem is not people being uneducated.
The problem is that people are educated just enough to believe what they have been taught, and not educated enough to question anything from what they have been taught.
Feynman: When we were talking about the atoms, one of the troubles that people have with the atoms is that they're so tiny, and it's so hard to imagine the scale.
The size of the atoms are in size - compared to an apple, it's the same scale as an apple is to the size of the Earth. And that's a kind of a hard thing to take, and you have to go through all these things all the time, and people find these numbers inconceivable. And I do too.
The only thing you do is you just change your scale. I mean, you're just thinking of small balls, but you don't try to think of exactly how small they are too often! Or you'd get kind of a bit nutty, alright?
But in astronomy, you have the same thing in reverse because the distances to these stars is so enormous, you see. You know that light goes so fast that it only takes a few seconds to go to the moon and back, or it goes around the Earth seven-and-a-half times in a second. And goes for a year, two years, three years before it gets to the nearest other star that there is to us.
But all of our stars are... the stars that are nearby in a great galaxy, a big mass of stars, which is called a galaxy, a group, well this, our galaxy is... what is it? Something like a hundred thousand light years, a hundred thousand years.
And then there's another patch of stars. It takes a million years for the light to get here, going at this enormous rate.
And you just go crazy trying to make too "real" that distance, you have to do everything in proportion. It's easy - you say the galaxies are little patches of stars and they're ten times as far apart as they are big.
So that's an easy picture, you know - he gets it. But you just go to a different scale, that's easier. You know, once in a while you try to come back to... Earth scale to discuss the galaxies but it's kind of hard.
The number of stars that we see at night is about - only about 5,000. But the number of stars in our galaxy, the telescopes have shown when you improve the instrument... Oh! We look at a galaxy. We look at the stars. All the light that we see, the little tiny and influent spreads from the star over this enormous distance of what? Three light years, for the nearest star. On, on, on! This light from the stars spreading, the wavefronts are getting wider and wider, weaker and weaker, weaker and weaker out into all of space, and finally the tiny fraction of it comes in one square, eighth of an inch, tiny little black hole and does something to me, so I know it's there.
Well, to know a little bit more about it, I'd rather gather a little more of this little, this tiny fraction of this front of light, and so I make a big telescope, which is a kind of funnel that the light that comes over this big area - 200 inches across - is very carefully organised, so it's all concentrated back so it can go through a... pupil. Actually, it's better to photograph it, or nowadays they use photo cells, they're a better instrument.
But anyway, the idea of the telescope is to focus the light from a bigger area into a smaller area so that we can see things that are weaker, less light, and in that way we find there's a very large number of stars in the galaxy.
There's so many that if you tried to name them, one a second, naming all the stars in our galaxy, I don't mean all the stars in the universe, just this galaxy here, it takes 3,000 years.
And yet, that's not a very big number. Because if those stars were to drop one dollar bill on the Earth during a year, each star dropping one dollar bill, they might take care of the deficit which is suggested for the budget of the United States.
So you see what kind of numbers we have to deal with!
I'm getting ready for going to uni so I'm gonna post a lot about it to keep myself motivated. These are some of my favourite people in math and physics. Also a reminder that science is not for an specific group. We all belong to it. Don't be afraid of choosing a male dominated field. Have a good day everybody.