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Ask HN: What is a science fact that blew your mind when you learned it?

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Re: Ask HN: What is a science fact that blew your mind when you learned it?

#121

Post by moistly »

m463 wrote: post #110
sloaken wrote: post #91

Earlier quoted context omitted.

OMG me too. I was having an eye exam. The technician had a black field with a bunch of lines. Holding a rod with a white dot, and told to let them know when it disappeared. I laughed, "Well that will only happen if you put it behind your back." They laughed, "Everyone has an astigmatism where the nerves enter the eye. We are looking for that or any other issues." I was so shocked when the dot disappeared. Also happy…

There is one driving your car too. :)

Not if your mirrors are set correctly. Lean your head to the side window, set the mirror so that it just misses the tail end of your car. Position your head over the centre console, set the mirror. There is now approximately no blind spot. You can fine-tune by careful observation on a multi-lane highway as people pass/you pass others. Done correctly, there is no blind spot.

Re: Ask HN: What is a science fact that blew your mind when you learned it?

#122

Post by emiliobool »

JohnDeHope wrote: post #118
cbruns wrote: post #108

Earlier quoted context omitted.

The explanation that makes the most sense to me, from wiki: Yet another insight is that your chance of winning by switching doors is directly related to your chance of choosing the winning door in the first place: if you choose the correct door on your first try, then switching loses; if you choose a wrong door on your first try, then switching wins; your chance of choosing the correct door on your first try is 1/3,…

The bit that gets me... If he opens one door, which is a goat, so there is 1 goat and 1 prize remaining... then the chance should be 50% staying put or switching, right? That's the part that gets me. The whole bit about 3 doors and opening one of them and "do you want to switch" is all a ruse, it seems to me. At the end of the day there are two doors, one with a goat and one with a prize, and however you choose betwe…

It would only be 50-50 if you could only pick from 2 options, but your initial choice is between 3 options.

Re: Ask HN: What is a science fact that blew your mind when you learned it?

#124

Post by [deleted] »

JohnDeHope wrote: post #97
drran wrote: post #46

Earlier quoted context omitted.

It's false information. It's debunked multiple times. "Watching" means "placing or turning on an additional detector", which ruins interference pattern. To develop intuition, look at double slit experiment made at macro scale using walking droplet.

I'd really appreciate a few links to this. I am on a youtube binge lately watching quantum dynamics lectures for lay people. The constant talk about "watching" and "observers" drives me crazy. I refuse to believe anything has anything to do with whether or not anybody is "watching" anything. Bouncing photons off of it? Sure I can see how that would affect all sorts of things. But if the bouncing photons alter what's…

[deleted]

Re: Ask HN: What is a science fact that blew your mind when you learned it?

#125

Post by jacknews »

drran wrote: post #46
loandigger wrote: post #18

The dual slit experiment. Run the experiment with no one watching it, it produces result A. Run it again and watch it, it produces result B. Watching the experiment changes the result. WTF????

It's false information. It's debunked multiple times. "Watching" means "placing or turning on an additional detector", which ruins interference pattern. To develop intuition, look at double slit experiment made at macro scale using walking droplet.

Exactly, there's no such thing as passively 'watching' a system at the quantum level.

In order to obtain the information you wish to 'observe', you need to interact with it.

That interaction 'collapses the wave function', or rather, you become part the wave function, but seeing it 'from the inside' looks different compared to from the outside.

Re: Ask HN: What is a science fact that blew your mind when you learned it?

#126

Post by AnimalMuppet »

RichardCA wrote: post #120
RichardCA wrote: post #117

Earlier quoted context omitted.

I'm sure I'll do a poor job articulating it. It's similar to bokeh that photographers are familiar with. You look at a light source and the light seems to bounce through the pupil and back out again. If there's a drop of liquid on your eyelashes you'll see a bokeh ring with interference ripples around the edge. I just remember as a child I thought it was strange, then in high school physics I saw how laser light was…

This is what I'm taking about, when I was a kid before I got fitted with glasses, I remember the world looking like this... https://photo.stackexchange.com/questions/99407/what-is-the-...

OK, but that's proof of the wave nature of light, not quite of the quantum nature.

Re: Ask HN: What is a science fact that blew your mind when you learned it?

#127

Post by RichardCA »

AnimalMuppet wrote: post #126
RichardCA wrote: post #120

Earlier quoted context omitted.

This is what I'm taking about, when I was a kid before I got fitted with glasses, I remember the world looking like this... https://photo.stackexchange.com/questions/99407/what-is-the-...

OK, but that's proof of the wave nature of light, not quite of the quantum nature.

Let's try to work the problem in a way that avoids pedantry, just for a moment.

This is one of my favorite PBS clips from the 80's in which Richard Feynman explains how strange the nature of light and by extension all of electromagnetic radiation.

https://www.youtube.com/watch?v=FjHJ7FmV0M4

If you listen carefully, you notice that he never talks about wave/particle duality (because he wasn't giving a classroom lecture).

What he does talk about is an electric field that waves slosh around in, and that something "elaborate and complicated" is going on at a deeper level.

That's what I'm on about, if you were pressed to explain it so that a bright child would get it, how would you do that?

Re: Ask HN: What is a science fact that blew your mind when you learned it?

#128

Post by jabirali »

drran wrote: post #46
loandigger wrote: post #18

The dual slit experiment. Run the experiment with no one watching it, it produces result A. Run it again and watch it, it produces result B. Watching the experiment changes the result. WTF????

It's false information. It's debunked multiple times. "Watching" means "placing or turning on an additional detector", which ruins interference pattern. To develop intuition, look at double slit experiment made at macro scale using walking droplet.

I love the “bouncing droplet” experiments. There are some cool videos of it on YouTube for those that want an intuitive macroscopic analogy to how quantum mechanics work.

Re: Ask HN: What is a science fact that blew your mind when you learned it?

#129

Post by jabirali »

mistersquid wrote: post #65

In Physics 2 (Light, Electricity, and Electromagnetism), I could not derive the correct answer for calculating the flux of an infinite sheet. TA: The flux is S for an infinite sheet. Me: How? We have S for this side plus S for the other which yields 2S! TA: For an infinite sheet, there is no other side. Me: O_O

To me that sounds mostly like a philosophical distinction. In most physics calculations, “infinite” just means “finite but so large that we can neglect edge effects”.

Re: Ask HN: What is a science fact that blew your mind when you learned it?

#130

Post by drran »

JohnDeHope wrote: post #97
drran wrote: post #46

Earlier quoted context omitted.

It's false information. It's debunked multiple times. "Watching" means "placing or turning on an additional detector", which ruins interference pattern. To develop intuition, look at double slit experiment made at macro scale using walking droplet.

I'd really appreciate a few links to this. I am on a youtube binge lately watching quantum dynamics lectures for lay people. The constant talk about "watching" and "observers" drives me crazy. I refuse to believe anything has anything to do with whether or not anybody is "watching" anything. Bouncing photons off of it? Sure I can see how that would affect all sorts of things. But if the bouncing photons alter what's…

If you want to develop intuition, look at this video: https://www.youtube.com/watch?v=nsaUX48t0w8 .

Please note that physics as science in general is advancing constantly, but mainstream physics advances in sprints. Currently, walking droplets and Pilot Wave Theory are not good enough to be included into mainstream physics.

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