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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?

#51

Post by rrobukef »

Stratoscope wrote: post #38

Electrons in a copper wire do not travel at the speed of electricity. Not even close. Electricity travels at nearly the speed of light. Electrons themselves travel like molasses: "In the case of a 12 gauge copper wire carrying 10 amperes of current (typical of home wiring), the individual electrons only move about 0.02 cm per sec or 1.2 inches per minute (in science this is called the drift velocity of the electrons.…

For AC, they move back as well. Thus electrons move less than 4µm from their original place (excluding Brownian movement, I assume)

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

#52

Post by milkytron »

perk wrote: post #32
cbsks wrote: post #23

I think "mind blown" is an accurate description when I first saw the Hubble Deep Field image: https://hubblesite.org/contents/articles/hubble-deep-fields I already knew that "the universe is incomprehensibly large", but seeing how many entire galaxies there were in a random dark patch of sky was eye opening to me.

Don't know exactly why, but thinking about the vastness of the universe always cheers me up. Thanks for sharing :)

As a kid, it used to weird me out to the point where I would forget what I was doing, get the chills, and enter a sort of trance. It never impacted me negatively, but pondering the scale of everything and how little of an impact we have on the grand scheme of the universe gave me a weird sensation.

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

#55

Post by posterboy »

znpy wrote: post #4

we can see our nose all the time, but our brain filters it out. if you close one eye and keep the other open you'll suddenly see one side of your nose.

> Can explain Quantum gravity

> Can explain DNA

...

> Can see his own nose

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

#56

Post by drran »

pier25 wrote: post #29

Gravity is not really a force or objects "attracting" themselves but a consequence of the curvature of spacetime. At least that's my pedestrian interpretation :)

What releases energy then, when objects are accelerated towards each other?

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

#57

Post by Xcelerate »

throw1234651234 wrote: post #44
Xcelerate wrote: post #31

A compressed spring weighs more than the same spring uncompressed. The moon and earth weigh less together than if you weighed them separately and added the values together. Most of the weight of solid objects is due to the high speeds and binding energies of the elementary particles within them rather than the rest mass of the constituent particles. The number of particles that exist is relative to how fast you are a…

>A compressed spring weighs more than the same spring uncompressed. This is false. The dilemma is that you can't "just weigh" a compressed spring without assistance. However, you can get around it by weighing a compression device with the spring, both when it's compressing and not compressing the spring. The weight will be the same.

You could not practically ever measure the difference in a lab, but it’s still a real effect. Look up the stress-energy tensor. I could equivalently say that a spinning ball weighs more than the same ball when stationary.

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

#58

Post by WrtCdEvrydy »

Stratoscope wrote: post #38

Electrons in a copper wire do not travel at the speed of electricity. Not even close. Electricity travels at nearly the speed of light. Electrons themselves travel like molasses: "In the case of a 12 gauge copper wire carrying 10 amperes of current (typical of home wiring), the individual electrons only move about 0.02 cm per sec or 1.2 inches per minute (in science this is called the drift velocity of the electrons.…

Yeah, Physics 2 blew my mind with things like this.

The electrons actually move mostly side to side as they bump into each other. Pushing power just pushes the ones further down the pipe into the light, not the ones entering the copper cable.

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

#59

Post by perardi »

kpwags wrote: post #5

That when we look up at distant stars, nebulas, & galaxies and the like...we are looking back in time. What we see could have been gone for decades, centuries, or longer.

“longer” is an understatement. The Andromeda galaxy, which is viewable by the naked eye, is 2.5 million lightyears away. And that’s the closest galaxy to us.

https://en.wikipedia.org/wiki/Andromeda_Galaxy

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