A rather daring demonstration of Newton’s 3rd law of motion. For every action there is an equal and opposite reaction.
Or, if object A (the woman) exerts a force, Fa, on object B (the bow) then B exerts an equal force, Fb, in the opposite direction. See how it is holding her up when she should fall? The man is experiencing his own 3rd law force.
"2 quick questions,(I’m asking you because at my university the closest I got to a particle physicist is a astronomer, and Google doesn’t help either)
1. Where does the north and south pole change on a magnet?
If you look at the pictures of bar magnets with iron dust all you can tell is that the magnetic field lines are smaller. You cant tell where the north switches to south and vice versa.
2. Do gravitons correlate to mass or the number of particles?
I know gravity is caused by the exchange of gravitons between particles, but there are different types of particles, some of which are heavier than others, so are the heavier particles more likely to exchange gravitons? Or is it just that the more particles the gravitons are exchanged
3. How do gravitons work?
If gravity is caused by the exchange of gravitons, and gravity has a infinite range then how does it work. Do gravitons just randomly go through space and hit something then go back to their owner? If they know where they’re going then they constantly exchange between the same few particles?
You say 2 and you immediately ask 3. I like your style. You should attend conferences.
OK, I’m going to come right out and admit that I don’t know the answers to 2 and 3. I don’t understand gravitons very well as it was always the last topic covered in any particle physics course (possibly cos nobody understands them very well?) Maybe Adam could weigh in here?
You might even have to look to String Theory for these answers and, if you’ve been reading my posts on that subject you’ll know I am of little help there.
As for 1. Hmm, let me think. I’ve honestly never considered this. I think the answer might be…that they don’t. First off, the iron fillings don’t care which pole they attract to, they’re easy. So when you scatter them near the bar magnet, they will attract to whichever pole of the magnet is closer. If they happen to be smack, bang in the exact middle, theoretically they will be equally attracted to both sides and won’t move. So you could look at that point as the change-over point.
As for another magnet, which is the only thing that will distinguish between North and South poles. Well I just did a quick experiment with some magnets I happen to have lying around and this is what happened.
While bringing the North pole close to the North pole the magnets would repel everywhere in that grey, mushroom-cap area. They would attract everywhere else. Similarly, the South pole of the magnets would repel in a mushroom-shaped area and attract everywhere else. So you could say that the switch-over happens very close to either pole and there is actually a huge overlapping area that is both poles, or neither.
You see, magnetism is a lot more complicated than the bar magnets you learn about in school. The fact is that every particle can have it’s own magnetic moment. Every atom, every electron even. And those magnetic moments can each be pointed any way they want. In ferromagnets (like bar magnets) those moments are mostly aligned and so you get an over-all global magnetization. Similarly, in ferromagnetic materials (like iron, cobalt, anything magnetic) these moments are easily aligned by an external field and they will become magnetic in a magnetic field (and residually, outside a magnetic field for a time. Most commercial bar magnets are magnetised in this way and can lose their magnetisation over time.
I hope I have explained this in an alright way. And that I haven’t gotten anything confused. Like I said, I’ve never really thought about this particular problem before.
Good luck with your thoughts about gravitons. And when in doubt, do an experiment!
Lnr mentioned how it’s good to put the spotlight on women in science, as apart from Marie Curie, there are so few that come to name. Here’s my two cents. This is Emmy Noether.
This lady was badass. She was a professor when women weren’t allowed usually. But that’s peanuts to her badassery, she was a Jewish professor in Nazi Germany, and when she was fired, she just did maths in her apartment with her students.
Now, Lnr’s the theoretical physicist, so she can probably explain this better than I can, but Noether’s Theorem is the maths that explains how conservation laws are able to work. She’s probably the most important lady in mathematics. It basically explains how our world is able to function. So while Curie was awesome. This is the lady that first springs to my mind about women in physics…and maths.
Lnr: I freaking love Emmy Noether! The University where she taught used to schedule her lectures under male lecturers’ names and have her along as a “teaching assistant”. But she would deliver the whole lecture. It was just to get around the ridiculous rules that said a woman couldn’t be a lecturer.
Noether is the best! It’s just so hard to explain why to non-mathematicians … Noether’s Theorem above is actually the easiest:
Part 1: There are some ways you could change the universe without changing physics. Like if you teleport the whole solar system 10 meters THAT WAY ==>, physics still works exactly the same. And the laws of physics don’t care about what time it is either: they will work just the same an hour from now. You could rotate everything 90 degrees and physics wouldn’t change.
These ways to change the universe without changing physics are called symmetries.
Part 2: some quantities in physics like Energy or Momentum which are always exactly the same in a given system. These facts are called conservation laws.
Noether proved that Parts 1 and 2 are EXACTLY THE SAME. If you have a symmetry, there is a corresponding conservation law, and vice-versa. Note that she didn’t write about anything particular to our universe, or about any particular law, but about all conservation and symmetry in all (un)imaginable universes. This guiding principle of how universes work came in very handy when quantum theory began unveiling utterly nonsensical aspects of our own universe: they turned out to bring whole new critically important conservation laws and critically important symmetries, always hand in hand.
Alas, that’s the most explainable of her accomplishments, not the biggest … she basically invented everything that makes PhD-level math what it is today. A smart undergrad could cover modern math as it would appear without her work.
An excellent way of explaining Noether’s theorem to the not-mathematician. Thanks plasticorc!
Not trying to ruin the pendulum thing, but the reason they don't hit each other is because they each have two strings which keep them centered. And the reason they have different swing times is because of the lengths of the strings.
Yes. All good points. We covered this on various reblogs. I never realized people thought they should hit each other. If you look at similar videos the pendula are nowhere near each other on the scaffold. They don’t interact at all. It’s a frequency phenomenon.
So can I ask you biological questions and get a scientific answer?
You can, though you should know, only one of us has any idea about biology!
But we are both adept at searching paper archives.
Adam: I’ll do my best. I’ve had a massive crash course in biology since I started my PhD. I’m decent with genetics, and cell biology, and pretty good on cancer biology, and can probably read up on the rest.
"The pressure variations due to the sound waves affect the flow rate of flammable gas from the holes in the Pyro Board and therefore affect the height and colour of flames. This is interesting for visualizing standing wave patterns and simply awesome to watch when put to music."
Skip to 3:38 in the youtube clip to hear it with the music. The lo-fi track used to demonstrate is sick, and makes it that much more amazing to watch.