#physics facts

[scienceisdope]

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[curium-killedthecat]

i learned this fact a while ago, and it’s still one of those good ones i go back to and think about:

if you took all the matter in the universe (that is estimated to exist) and turned it into a black hole, the size of that black hole’s event horizon would be the size of..

our observable universe.

yep, that’s right. this is because the schwarzchild radius - that is, the radius of an event horizon of a black hole - is proportional to is mass. so we can figure out how large an event horizon would be using its mass - thanks to general relativity.

imagine our universe to be a fluid of constant density - which is a good approximation of our universe on a large scale, since matter is spread out pretty evenly.

if we take a sphere out of our universe with a radius, the mass inside it depends on its volume - this volume of a sphere is proportional to the cube of its radius. since density is constant, the mass grows with the cube of the radius.

so essentially, the schwarzchild radius grows faster than the actual radius of the sphere. because of this directly proportional nature, if you start with a small sphere of the universe, its schwarzchild radius is much smaller then a the sphere itself. but as you take larger and larger regions of space, the schwarzchild radius grows at a faster rate than the spheres actual size.

this means at some point, if the sphere is large enough, its schwartzchild radius can become bigger than the sphere’s own radius. funky, i know. but it gets weirder. our universe has a density very close to the critical density, which is the average density needed for the universe to gather enough force to halt its expansion. i digress.

for this critical density, the schwarzchild radius turns out to be equal to the size of the observable/visible universe.

so, do we live in a black hole? ….probably not. this thought experiments doesn’t take things like dark matter or energy into consideration, and we don’t have a special centre of sorts to form the nucleus of our supposed black hole.

also, this ignores that we live in a wonderfully expanding universe, where the only measurement of an observable universe is a classical, non accelerating one. if we did live in a black hole, we could only see in one direction which would be opposite to the singularity, and everything would be crunching towards the singularity.

alas, it is fun to think about on a late night. maybe we do live in a black hole.

[nancydrewgamesofficial]

Did you know that #EmmyNoether was a brilliant mathematician behind some of physics' greatest breakthroughs? 🔬 In honor of #WomensMonth we’re highlighting the woman who gave us Noether’s Theorem and changed the way we see the universe! 💫

[the-fact-site]

White holes, as in reverse black holes that push out rather than suck in, are theoretically possible. We just haven’t found one yet. #FACT

[artrizzalmao]

Energy is liberated matter and matter is energy waiting to be liberated

Bill Bryson

[teachersource]

Did you know? If you took out all the empty space in our atoms, the entire human race could fit in the volume of a sugar cube The atoms that make up the world around us seem solid but are in fact over 99.99999 percent empty space. An atom consists of a tiny, dense nucleus surrounded by a cloud of electrons, spread over a proportionately vast area. This is because as well as being particles, electrons act like waves. Electrons can only exist where the crests and troughs of these waves add up correctly. And instead of existing in one point, each electron’s location is spread over a range of probabilities – an orbital. They thus occupy a huge amount of space.

[stellarastronomyfacts-blog]

[uchicagoadmissions]

Did You Know: Albert A. Michelson

Did you know that Albert A. Michelson, the founder of the Department of Physics at the University of Chicago, was the first American scientist to win a Nobel Prize?  Michelson won the Prize in 1907 for his accurate measurements of the speed of light.  His most significant lasting scientific achievement was perhaps his participation in the famous Michelson-Morley experiment, which baffled the scientific community and was heavily influential to Albert Einstein’s special theory of relativity.  The Ryerson Laboratory on campus, according to Michelson’s instructions, was built without the use of iron to avoid any magnetic interference with Michelson’s experiments!