Always been amazed at how really small things (atoms) look a lot like really big things (solar systems) (ya, ya, same forces...)
Scale of the Universe
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Re: Scale of the Universe
#12How not to feel sooooo small and insignificant after that !?
By looking at the smallish end of the scale, of course. I am so much bigger and more signifigant than a cilliate protist!
Re: Scale of the Universe
#13Always been amazed at how really small things (atoms) look a lot like really big things (solar systems) (ya, ya, same forces...)
They don't really -- in particular, the picture you might have from high-school physics lessons of electrons orbiting a nucleus like planets orbit a star is really wrong. And it's not really the same forces; the way an atom looks is mostly down to the electromagnetic force, whereas the way a solar system looks is mostly because of gravity.
On the other hand, it is true that Newtonian gravity and the electrostatic force (i.e., what the electromagnetic force becomes when you make the approximation that there are no moving charges) have very similar mathematical forms, with the same sort of differential equation governing them. What Newtonian gravity and electrostatics have in common is mostly that they are convenient simplified approximations; you could say that they're so similar because there's a limited repertoire of differential equations simple enough to make good approximations. (There's a bit more to it than that; for instance, inverse square laws fall naturally out of the geometry of a 3-dimensional world.)
Re: Scale of the Universe
#14How not to feel sooooo small and insignificant after that !?
Some people get depressed when they find out how huge the universe is... What is the big deal about bigness? A cow is much bigger than you, but it is a ridiculous animal and you are a valuable person. You know it's a cow. It doesn't know anything. it just stands there eating grass (grass!) and mooing. And if it were bigger, that would only make it more ridiculous.
- David Deutsch
Re: Scale of the Universe
#15Always been amazed at how really small things (atoms) look a lot like really big things (solar systems) (ya, ya, same forces...)
They don't really -- in particular, the picture you might have from high-school physics lessons of electrons orbiting a nucleus like planets orbit a star is really wrong. And it's not really the same forces; the way an atom looks is mostly down to the electromagnetic force, whereas the way a solar system looks is mostly because of gravity. On the other hand, it is true that Newtonian gravity and the electrostatic for…
Indeed, some patterns in nature might look familiar. For instance, stellar matter in novae seem a lot like clouds but only because human psychology is really good at pattern recognition.
As for Newtonian physics versus relativity Brian Green’s Elegant Universe TV show (and book) does a great job illustrating the differences in an entertaining way.
If you’re into that type of thing.
http://www.pbs.org/wgbh/nova/physics/elegant-universe-einste...
Re: Scale of the Universe
#16How not to feel sooooo small and insignificant after that !?
"You're really only very small, and life flows on within you and without you."
Re: Scale of the Universe
#17Can someone explain to me if the Universe is supposed to be 14,000,000,000 years old, how can it be estimated to be 93,000,000,000 light years wide?
Assuming the Big Bang, doesn't that imply the 'outer matter' must have an average velocity of about 3.3 times the speed of light?
Re: Scale of the Universe
#18it's still nice but it's been here before: http://news.ycombinator.com/item?id=1835460 BTW: since there's no search feature to check for older posts, I suggest you use google: site:ycombinator.com
I've also created an API to look up URLs that have been posted to HackerNews.
http://api.ihackernews.com/getid?url=http://uploads.unground...
Re: Scale of the Universe
#19Can someone explain to me if the Universe is supposed to be 14,000,000,000 years old, how can it be estimated to be 93,000,000,000 light years wide? Assuming the Big Bang, doesn't that imply the 'outer matter' must have an average velocity of about 3.3 times the speed of light?
According to general relativity, space can expand faster than the speed of light. So while what we can see is limited by the speed of light, the size of the universe is not.
Re: Scale of the Universe
#20Can someone explain to me if the Universe is supposed to be 14,000,000,000 years old, how can it be estimated to be 93,000,000,000 light years wide? Assuming the Big Bang, doesn't that imply the 'outer matter' must have an average velocity of about 3.3 times the speed of light?
Because the distance has also grown since the light travelled. It's expanding.