/sci/ - Science & Math

[Anonymous No.1756990]

So, /sci/, What is the size of an Black hole?

Is it just a single point?

I mean, even the subatomic particles have some size and dimension.

[Anonymous No.1757004]

>>1757002
Oh my, LOL.

[Anonymous No.1757002]

>>1756990
>subatomic particles have some size and dimension
nope
"atom" means undivideable. what makes you think there are particles in an atom? that's just silly

[Anonymous No.1757010]

The singularity is incredibly small. The apparently light-stopping "black" part of a black hole is just the event horizon, which isn't particularly special apart from being the distance from which not even light can escape without being infinitely red-shifted.

[Anonymous No.1757013]

>>1757002

The guys that worked on the Manhattan project would like to have a word with you

[Anonymous No.1757018]

>>1757010
I heard that even black holes range in size from an atom to about 30~ miles.

[Anonymous No.1757026]

Smaller than a plank's length, that is what we are certain about.
Likely though, is it has no size at all. It is literally dimensionless.
Dimensionless Point Singularities.
They have no volume, but plenty of mass/energy.

[Anonymous No.1757028]

Depends on what you define as the black hole. The hole itself is a singluarity, it is really a single point.

Usually when people talk of a black hole, they mean the space inside of the Schwarzschild radius. This is the distance to the actual black hole in that no light can escape, therefore it appears black.

[Anonymous No.1757029]

>>1757002

Can't get away from dem right-wing christians.

>>1756990

The real answer to this question is "We dunno lol". Seriously, there are theories, but we can never actually know, since black holes like to swallow up everything they take in, including light.

I mean, normally they start off as the remnant after a supernova (as far as I know), so generally shit loads of neutrons and protons. The protons will change to neutrons because it's energetically favourable, I think. If there is enough mass and the remnant is compact enough, then it will go into a black hole.

After so much time, I get the feeling that quantum gravity will interfer with the process, as the mass will be so squashed together, the particles within it will reach ridiculous energies. Perhaps the strong force between the underlying quarks may stop the expansion?

There are many possibilities.

[Anonymous No.1757032]

>>1757018

That is a layman's description when there is a lack of separation of the event horizon and the singularity.

[Anonymous No.1757036]

from what I understood, they have mass just like a planetoid or star or any other celestial body, just that the mass keeps any light from escaping. under that definition, is it not possible that a black hole be of any size, i.e. our sun's size? yes it'd be retardly dense, but why does that mean it would collapse in on space and time?

unless you're all "hurr durr quantom mechanics" and say that shit doesn't have to make sence to believe in it.....

[Anonymous No.1757043]

truth is we don't know what happens inside a black hole. we assume them to be a singularity but only because once the quark degeneracy force is overcome by gravity we know of no other force that would stop them from becoming a singularity.

there are no current models that predict exactly what is happening, we just assume it to be some kind of singularity because we don't know why it wouldn't be.

[Anonymous No.1757047]

>>1757036
Yes, and that is why the LHC made the headlines. Some idiots are scared it will create micro black holes.

But, there is also Hawkings Radiation, so no worries.

[Anonymous No.1757052]

>So, /sci/, What is the size of an Black hole?
Easy!
Step 1: obtain a ruler
Step 2: pull down pants
Step 3: bend over with your ass facing a mirror, and your head between your legs.
Step 4: use the ruler to measure the size of your black hole, using the mirror to see the ruler.

[Anonymous No.1757054]

anyone have a link to that article about the guy that did the math on a black hole singularity being the big bang of a universe inside it?

[Anonymous No.1757072]

Question about hawking radiation
Its a result of vacuum energy around the event horizon, right? One particle gets sucked in but the other doesnt?

Is there some bias as to which particle gets sucked in? Charge for example? If not, wouldnt hawking radiation consist of just as much antimatter as matter? And on average the black hole wouldn't lose any matter?

[Anonymous No.1757083]

It can be massive or incredibly tiny. The density is just so great that light can't escape its gravity. If you take Erf and make it the size of a pea it would be a black hole the size of a pea, but if you were to take the sun and make it the size of a bowling ball you would have a black hole the size of a bowling ball. Take all of the matter in the galaxy and make it the size of Erf and you get a black hole the size of Erf.

[Anonymous No.1757084]

>>1757026
This is very close to the answer, the size of the black hole is dictated by the original mass of the object. Once the mass is shrunk down enough to create enough gravity to stop any expansion of itself it will become a black hole. You could become a black hole if you were somehow shrunk down to an infatesimal size.

[Anonymous No.1757085]

You misunderstood how that works then.

Some vacuum particles have a vector 90º to the event horizon and have a velocity of c. Some of these particles are formed half way in the event horizon and are literally ripped in half.

The half particle that is sucked in reduces the mass of the black hole and the half that escapes is the radiation, the half that escaped.

[Anonymous No.1757091]

>>1757072

it doesn't matter which particle gets sucked in, both matter and antimatter have positive mass and positive energy.

hawking radiation works because the massive gravity of a black hole amplifies a fluctuation in spacetime and helps create a particle pair, so half the mass of the particle pair actually came from energy from the gravitational field of the black hole.

there's no negative mass or energy involved, that is impossible.

[Anonymous No.1757096]

>>1757084
Thank you, I think, but I was spot on, within the limits of normal language.
Dimensionless points is the majority of what I study. I find it interesting something can have an infinite density.

[Anonymous No.1757107]

>>1756990
>I mean, even the subatomic particles have some size and dimension.

This is incorrect. Where are you geeting such bullshit from? Troll?

[Anonymous No.1757135]

>>1757091
>the massive gravity of a black hole amplifies a fluctuation in spacetime and helps create a particle pair
How? I sort of understand pair production when a gamma ray interacts with a nucleus, but are you saying a strong gravity field alone can be enough to form a particle/antiparticle pair?

I understand that the equation balances out, but how does a black hole lose mass if it gains one of the two particles? If it was an antiparticle that annhilated a regular matter particle in the singularity,i could get it, but if it just gains a proton, and it spits out an antiproton, and matter/antimatter both contribute to gravity the same way, it just seems like even though charge symmetry is maintained, theres still more bending of spacetime in the universe than there was before.

[Anonymous No.1757149]

>>1757107
DERP BECAUSE THINGS WITH NO SIZE COME TOGETHER TO FORM SOMETHING WITH SIZE

[Anonymous No.1757163]

>>1757002

God damn, I hope for your sake you are trolling

[Anonymous No.1757165]

>>1757149
You are now aware that nothing ever touches. There are only repelling electric forces that make you think you touch anything.

[Anonymous No.1757174]

>>1757149
>>1756990

Exactly, things with no size can come together to make somthing with size. You could take any object an decompose it into a set of "points" with no size.

Fundemental particles, like quarks, electrons, etc, have no size.

\thread

[Anonymous No.1757179]

>>1757107
>doesnt know about my strings

[Anonymous No.1757185]

>>1757135

The particle pair consists of a particle with negative energy and a particle with positive energy. This is well within the limits of conservation.
The particle with negative energy can be absorbed and the particle with positive energy in emitted.
To an outside observer, the black hole emitted a particle. Conservation means a corresponding negative particle went into the black hole.
It is that simple.

[Anonymous No.1757186]

>>1757174
You're ruining every thread on /sci/ today with your shitty 1990s image macros and poor spelling and understanding of physics.

[Anonymous No.1757189]

lol @ u gaiz

integer points adding up to making particles FFS

No wonder they want to cut funding for so-called "science"

[Anonymous No.1757199]

>>1757186
Don't hate him. He is just bored. He could be a researcher that needs a break.
I mean, he must be important if he is here at /sci/.
To Troll:Tell me, did you earn a Ph.D. or atleast a masters?

[Anonymous No.1757207]

>>1757185
How would a particle with negative energy act differently if we made one in a lab?

[Anonymous No.1757212]

>>1757135
>but how does a black hole lose mass if it gains one of the two particles?

because mass of the particles came from the black hole's gravitational energy, which amplified a perturbance in spacetime causing a particle pair to form.

there are no particles in the singularity for antiparticles to annihilate; there are no particles in there at all. it is just pure gravitational energy. and anyways, particle+antiparticle annihilations do not net zero energy, they net a large amount of positive energy.

[Anonymous No.1757218]

We don't really know how gravity works, either.

[Anonymous No.1757226]

>>1757207
You cannot make one in a lab. It is an antiparticle, but keep the language simple so everyone can follow.
It is needed because of conservation. Since the particle observed has a positive energy, the corresponding anti-particle, from the observers frame of reference, must be negative.

To those who do not know a particle from an antiparticle, think of it as one whole particle ripped in half along the good/evil seem. The nega particle goes bye bye and the goody two shoes particle says hello.

[Anonymous No.1757243]

>>1757186
Listen little man, believe whatever the fuck you want. I was just trying to guide yall in the right direction. Yall seems to be using many many faultys "facts". I imagine pop-science seems fun and all, but it is shit-tier, and most of it is downright wrong.

[Anonymous No.1757256]

>>1757185
>>1757207
>>1757226

whoa whoa whoa wtf /sci/

there are no particles with negative energy, certainly not antiparticles.

not in hawking radiation, not in the standard model, not even in string/m theory. negative energy simply does not exist according to our current understanding of physics.

[Anonymous No.1757257]

>I mean, even the subatomic particles have some size and dimension.

No,
In particle physics, "point particle" is synonymous with "elementary particle", which is defined as a particle without structure or, equivalently, as a particle which is not made up from component parts. According to the Standard Model of fundamental particles and forces, quarks, leptons and the (non-composite) vector bosons are point particles in this sense. There is no experimental evidence for any of the elementary particles having spatial extent, and so they are usually considered to be point particles in the more general sense too (at least to the limited extent that the concept of a "particle" is meaningful in quantum field theory.)

[Anonymous No.1757260]

>>1757212
At what point does the black holes mass decrease? When the particles spawn, or when the negative energy particle approaches the singularity (and interacts with the positive energy)? Or is that the same thing.

>>1757226
Still feels like a convenient mathematical construct, but I understand why its necessary to make the equations balance.

[Anonymous No.1757262]

>>1757091
the way this is worded makes it sound like the energy -> matter -> energy continuation of events means that hawking radiation has an effective net change of 0, but it should be that the energy present there becomes matter, from there half the matter created (thus half the energy that was in the black hole area), 50% of this energy excapes, so it's that much smaller....I go this right?

[Anonymous No.1757263]

>>1757257

src: http://en.wikipedia.org/wiki/Point_particle

[Anonymous No.1757265]

>>1757226
>energy
>good/evil

out of the gene pool, now.

[Anonymous No.1757274]

>>1757262

yeah, basically.

it gets misstated all the time that hawking radiation is a negative mass particle colliding with the singularity and canceling out but that is impossible because negative mass does not exist.

what really happens is the energy from the singularity makes two positive mass particles, one of which escapes and one of which collides back with the singularity. the net effect is one particle escapes the black hole and its mass is reduced.

[Anonymous No.1757277]

>>1757274
>mass is reduced

Couldn't resist, I needed some comedic relief after all that

[Anonymous No.1757279]

>>1757256
Take note, I said from the frame of reference of an observer. That is a key point in Hawking Radiation.
It is also the only way to conserve energy without quantum tunneling from inside the event horizon.

Now. I want to nail your feet to the floor and remind you that physics is a liberal art for a reason. We may be able to speak in complex terms with each other, but the art is the ability to reform these concepts to fit a language anyone can understand.
How many people do you think know quantum tunneling is not a star trek universe plot device?

[Anonymous No.1757285]

>>1757279
uh, I thought you were being literal, you didn't make that "to an observer it would appear" stuff clear enough to me. Shouldave picked up on that when I asked about creating one in a lab.

[Anonymous No.1757286]

>>1757265
Hand over any and all liberal art degrees you may have or will have.
Liberal arts is not about knowing the truth ourselves. It is about presenting the truth in a message people will understand. If you try to limit the view of the universe we have to the elites of our fields, then you should not have your degree to start with.
And my analogy works fine for people who do not know the finer details.

[Anonymous No.1757289]

>>1757285
I did say that, repeatedly.

[Anonymous No.1757295]

>>1757286
>If you try to limit the view of the universe we have to the elites of our fields, then you should not have your degree to start with.

i disagree, its fine for those who want to, to focus in depth and leave the PR and all that other junk to people capable of doing so.

more efficient to play strengths.
some people are just bad at talking, but damn good with numbers, no fault of theirs, but it is quite closed minded of you to assume that a scientist must be articulate to those outside of the field.

[Anonymous No.1757303]

>>1757295

Then how can you put words around new concepts that no one has yet described?

To make a derivative, you only need follow instructions. To integrate a formula, you must learn the art. The difference is the same between a masters and a Ph.D.

[Anonymous No.1757323]

>>1757286
>Liberal arts is not about knowing the truth ourselves.
Physics truths and human truths are very different things. When you can write an equation for the grief someone feels at the death of a child, or plot a graph showing state vs nation, then you can claim to be master of all knowledge. Until then, learn2perspective

[Anonymous No.1757338]

>>1757323

Physics is not all about math. Math needs context, an explanation.

To teach, you must be able to explain those concepts in a fashion that can be understood by your students.

To teach is to welcome new blood into our flock and ensures the continuation of sciences. To not teach, either through publication and lecture or in the classroom, is to do science a great disservice.

The point of our work is to first learn, then teach. Our field may be interesting, but it could be replaced by any other field. The point of having an academic society is unchanged. To first learn, then teach.

[Anonymous No.1757340]

The size of a black hole is the size of its event horizon. If it is not rotating, then it is a sphere with radius of 2Gm/c^2, where m is its mass, G is the universal gravitational constant, and c is the speed of light.

[Anonymous No.1757352]

>>1757340
Hi. Welcome to 4chan.
You must be in highschool right now?
The first thing you should ask your teacher right now is about the difference between the event horizon and the singularity. If he is a good teacher, you will understand that a 'black hole' is a misconception. Bonus points if he tells you the singularity has an upper limit of one plank's length.

[Anonymous No.1757354]

>>1757352
>he thinks the Planck length has any physical significance

[Anonymous No.1757355]

>>1757352
Sorry, I should say one plank's radius. Stupid me.

[Anonymous No.1757361]

>>1757338
Yes, I realise physics isn't all about math - although it is really let's face it - but that wasn't quite the point of my post.

Liberal arts are about a different set of truths. Human truths and physical truths are very different things. An electric shock might kill you, a book might stop you killing yourself.

Physics is also a mixture of understanding yourself and communicating the understanding to others.

[Anonymous No.1757364]

>>1757361 Physics is also a mixture of understanding yourself and communicating the understanding to others.

Exactly.

[Anonymous No.1757371]

>>1757338
>Physics is not all about math.
hehe you say
>Math needs context, an explanation.
math is its own context

[Anonymous No.1757372]

>>1757352
No, I am not in high school. I have a 4-year physics degree. The size of black hole is the size of its event horizon. You may shut your ignorant mouth now.

[Anonymous No.1757377]

>>1757372
Tee hee. I still remember what it was like back then.
Did you read XKCD today? You should. It says alot about you right now.

EPIC WIN: Referencing XKCD in a thread

[Anonymous No.1757380]

>>1757355
No you shouldn't have said anything at all because you are a fucking moron. There is no such thing as a planck radius, planck length has nothing to do with a black hole, and you're not even spelling planck right. Go back to 9th grade biology. At least wait until you take high school physics before you start pretending you understand something.

[Anonymous No.1757382]

>>1757372
>a 4-year physics degree

lolwut. I have a MSc, which is a real degree.

[Anonymous No.1757389]

>>1757377
Back when? I don't read xkcd because I'm not a fucking college student. Grownup here.

[Anonymous No.1757390]

I thought Hawkings radiation was disproven.

[Anonymous No.1757395]

>>1757382
You do not have a MSc or any other degree in physics if you are the one who replied to me.

[Anonymous No.1757397]

This thread should have ended about ten posts ago

[Anonymous No.1757401]

>>1757380
Forgive my misspelling, but maybe you should consider all the units that can be derived from Planck's constant.

This might make sense to you then.

F = (m'1*m'2)/r^2

[Anonymous No.1757403]

>>1756990
the centre of the back hole where all the mass is does have a size, could be something like 30 km or a couple of centimetres. bigger block hole, bigger size.

[Anonymous No.1757404]

>>1757401
>units
>derived
>from Planck's constant

[Anonymous No.1757405]

>>1757340
This is correct. The size of a non-rotating black hole is <div class="math">\frac{2Gm}{c^2}[\eqn]</div>

[Anonymous No.1757408]

>>1757405
<div class="math">\frac{2Gm}{c^2}</div>

[Anonymous No.1757412]

It's even smaller than your dick! amazing!

[Anonymous No.1757413]

>>1757401
>F = (m'1*m'2)/r^2
get back to class. how's junior high? getting bullied a lot?

[Anonymous No.1757414]

>>1757403
Wouldnt the intense gravity smoosh everything together? Like fusion?

[Anonymous No.1757418]

>>1757413
Your compulsion to be considered the oldest and most qualified person in the thread must be exhausting

[Anonymous No.1757425]

>>1757418
No, what's exhausting is having remedial high schoolers in the thread.

[Anonymous No.1757426]

>>1757408
That would be the Schwarzschild radius.

[Anonymous No.1757429]

>>1757425
Was that a self reference?

[Anonymous No.1757440]

>>1757389

>doesn't understand past reference

[Anonymous No.1757441]

>>1757426
correct

[Anonymous No.1757444]

/sci/ is like two people that get on eachothers nerves, but get have to share a bed and end up making sweet, sweaty /sci/ence all night long, then have some kind of remorse in the morning and go back to hating eachother

[Anonymous No.1757446]

>>1757429
no U!

(way to go on the whole not-acting-like-a-high-school-er)

[Anonymous No.1757449]

>>1757389
Back when I did not have a Ph.D. in astrophysics and started researching both computational physics and the nature of the gravitational constant. Wolfram inspired me to do some research into computational physics. Really fucking interesting.

[Anonymous No.1757456]

>>1757449

The crazy shit with the networks?

[Anonymous No.1757457]

>>1757449
wolfram is gay.

[Anonymous No.1757459]

>>1757446
I am sorry, but I find it difficult to follow your...arguments.
I realize that you may be frustrated, but I doubt provoking frustration from anyone else is a good idea. I suggest you make yourself a cup of tea and read a book.

[Anonymous No.1757475]

>>1757459
no u