Random Thought Thread

fonedork said:
What about their toilets swirling the opposite way?
Click to expand...
fake-news.jpg

You can change the direction the water swirls down in your sink by rotating the water in either direction. Coriolis doesn't really affect such small bodies of water.
More influenced by subtleties such as direction the water was introduced from or structure shape of the basin.
 
Okay so I'm sitting at the beach on my vacation...


Having a thought experiment while dictating to my phone


It seems natural that prehistoric people with no knowledge of the universe or the solar system or even the world would think the world was flat. They had no way of knowing anything about how planets form or how gravity works. They didn't have telescopes that they could view other planets and I'll bet most of them were born lived and died and never gave much thought to gravity, what it is and how it works.

Gravity is kind of a force, but really is an effect. I think of it as the displacement of spacetime by mass where a straight line is curved because the space-time is displaced. That's probably wrong, but something that we all know that isn't wrong is that all matter has a gravitational attraction to other matter and the larger the mass the larger the force. And the farther away you get from that matter the less force it exerts on you. Much like a pinpoint of light such as a candle light emits light in all direction and it becomes dimmer the farther away you get. And that's the key really, it emits light an all direction. Light moves away from that candle in a straight line, but all of the light rays emitting from that candle describe a sphere, meaning they go all directions but originate from the center of the light source, the flame of the candle.


If you have a large mass in a room, it will exert a gravitational attraction to other matter in that room regardless of the orientation. If you set a mass beside it, it will attract it from the side. If you hang a mass above it, it will pull it down. If you set a mass below it, it will pull it up. These are all easily measurable effects that can be measured in labs with sensitive scales and this has been done many times and with the correct tools at your disposal anyone could make these measurements. Gravity and its effects are not a conspiracy theory or a secret. Only prehistoric people lack the means to measure it but it is not even particularly challenging today.


Matter will be attracted to other matter and this is the basis of planetary formation where dust and other particles with mass in space become attracted to each other and eventually form a sphere. You see, the closer you are to the mass the higher the gravitational force and, just like on Earth where gravity is stronger at sea level than it is up in a high altitude airplane, gravity will be stronger in the low areas of a planet that is forming and will attract more matter until you form, roughly, a sphere. And, thus, every planetary object that we are able to observe in the solar system is roughly spherical. Not perfectly round, but, taken to scale, at least as good as a decent ball bearing.

Now, this thought experiment. It's about 10:00 in the morning, so given this is my vacation this is about as sober as I'm going to be today

Let's, for the sake of argument, let's say there was a planet that was very old and the core had cooled and was solid and it was round and some sort of intergalactic mishap somehow caused it to be cut in half. Maybe a gamma ray streaming from a neutron star cuts it in half like a laser beam. I don't know. It's a thought experiment. But you somehow end up with a planet cut in half. And, for whatever reason, one half separates from the other half (for whatever reason) and you end up with a planetary body that actually is a flat plane on one side.

So let's think this through. This imaginary planet in our thought experiment. Let's put water on it, what would happen? We have a very good solid understanding of exactly how gravity works. The hows and whys may be debated but since Sir Isaac Newton and his falling apple the basic behavior of gravity is very well understood. If you were to put water on that flat plane, it would all rush to the center of that disc because that's where the gravity would be strongest. It would swell the same way that matter and particles behave during any planetary formation. You would end up with a disc that had a bulge in the middle with all the water in it. In order to have continents in that water, they would have to stand higher than that bulge of water meaning they would have to stand high on that flat plane so they would not be submerged.

If you had any land near the edges of that disc, and a person was standing on that land, it would feel like they were standing on an inclined plane. An inclined surface, even though it's a perfectly flat disc. Because the effect of gravity would pull them towards the center of that disc where it is strongest. Because that is how gravity works. In order for the land to feel level, it would have to be inclined to be perpendicular to a line drawn from that surface to the center of gravity. So the outside of the edge would either feel like you were standing on an inclined surface, or it would have to be angled to be perpendicular to gravity so that you can stand on it.

So, you now have a flat planet (flat on one side where we are conducting our thought experiment) But the center of it has to be pushed out so that continents in the ocean aren't submerged and the edges have to be angled over to be perpendicular to the force of gravity or you would just slide into the center. And you begin to take on a shape... A sphere. Otherwise you could have no continents with oceans interspersed between them and you could have no land near the edge of the disc that you don't simply slide in towards the center of the Earth. Because that's how gravity works.

Unless you want to say the gravity works different on this hypothetical planet. But in order for this to be feasible, now you have an extremely improbable shaped planet and gravity that works special differently there.

Or, in my mind, perhaps the earth is a sphere because that is much much simpler and does not require complicated mental gymnastics to make it work. Of course it's a sphere. What else could it possibly be? Imagining it to be anything other than a sphere is literally magical thinking. So you're stuck either believing it is magic, or it is round like the scientists have been explaining to us for a thousand years. Even if I wanted to discount the direct firsthand views of numerous people who have been a distance from the earth and have looked at it and have seen it to be a sphere, if I wanted to simply believe what I can see with my own eyes and discover with my own mind, I'm going to choose the simple one that doesn't require magic over the one that is pretty clearly nonsense when you give it any rational thought. Because I don't actually believe in that kind of magic. I believe what I can see with my own eyes and can discover through simple critical reasoning.

At a certain point you do have to take somebody's word for something. I don't own the scales to measure gravity. And I lack Sir Isaac Newton's genius and was not able to discern the laws of gravity by myself. But at some point we have to stand on the shoulders of others. They're not all in on some grand conspiracy theory and I feel sorry for anybody who has such a damaged and deranged view of humanity to think there could be some form of massive conspiracy theory reaching back centuries to lie to the people of the world and tell us this Earth is the sphere when it is actually flat. It seems far more likely to me that people are telling the truth and the earth is actually a sphere, even if I have not been able to go up into space and look down upon it myself.
 
There are some interesting fundamental questions about gravity. One relates to antimatter. The hydrogen atom (proton and electron) is simple and well understood. One can make the antimatter counterpart (antiproton and positron). The states and energy levels have been found to be the same, but they are measuring the response to gravity to test symmetries in the theory. A fellow grad student with me was offered the chance to join that effort. I was frustrated when he turned it down to putter around as a teaching assistant.
 
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