/sci/ - Science & Math

That's quite an interesting question.

I have no fucking clue.

>>4503020

they condensate into a very little tiny point?

The centripetal force wouldn't be enough to hold the body's molecules together, the atoms would most likely all separate long before it reached close to the speed of light.

>>4503037
This implies that the centripetal force would increase as the rotational velocity increased. It would not.

>>4503039
and how about an atom rotating close to the speed of light? does it even make sense to say that of an atom?

>>4503045
It is not my knowledge that an atom has ever been recorded spinning anywhere near the speed of light. However, I imagine if this ever happened then the atom would break down into Protons and Neutrons. If your next question is the same but with Protons and Neutrons spinning, the same would apply, they would break down into their respective Quarks and so on and so forth.

This touches on the epistemology of Infitism. Look it up.

>>4503020
>to a body that rotates at a speed close to the speed of light

It contracts accordingly....DURRR

>>4503020
There is nothing special about rotation of large bodies. You can just break them up into smaller linear parts, and those parts will object special relativity, and contract and shit if needed.

Rotation doesn't exist for small object, so your question is meaningless. A electron, quark, ect, are point particles, That can't "spin" in the way you think about "spin".

>>4503044
Yes it would.

>>4503072
>using newtonian mechanics for relativity problems

>>4503088
>Not the point.
I never claimed it would hold in the relativistic limit but OP stated that centripetal force was independent of rotational velocity which is nonsense.
Relativity is irrelevant because no star will ever get into the relativistic domain without flying apart.

>>4503096
op here, i never claimed that, it was someone else

>>4503096
>implying we don't use relativity for stars

Are you really that stupid?

>>4503096
huh? we need relativity to describe mercury's orbit around the sun.

>>4503039
but what if the body is so massive, that its gravity is enough to hold it together.. surely there are bodies massive enough in the universe.. or would they all be black holes? in any case, a black hole is still a body.. sort of.., what would happen to it?

>>4503116
Yes

>>4503116
>>4503111
The rotation of stars is not fast enough to require relativity. Mercury's orbit is affected by the curvature of space which has nothing to do with centripetal force.

>>4503100
Well then the answer to your question is that stars would break up long before reaching the speed of light.

>>4503120
>Gravity holds it together

WTF DO YOU THINK A PLANET IS DUMFUCK!
HOW FUCKING OLD ARE YOU?

>>4503133
except pulsars, ie neutron stars

>>4503132
are you even following the thread? ill explain my post to you: suppose a cloud of dust so massive, that while it contracts, it speeds up enough to approach the speed of light, and yet it is so masive, that the gravity of the body is enough to counter the centripetal force..
planets? wtf are you talking about

>>4503133
Super-Massive objects Rotate super fucking fast all the fucking time. Stop talking out of your ass son!

http://en.wikipedia.org/wiki/Frame-dragging

>>4503142
large dust accretions can go straight to black hole without becoming supernova. probably how supermassive/galactic black holes form.


this nmeans main sequence stars have upper limits to their size

>>4503143
WTF are you talking about?
The centripetal force is in the same direction as gravity you dipshit. The centripetal force is directed inward, gravity is directed inward.


Take a few deep breaths and rethink what you are trying to ask.

>>4503147
I mentioned stars, as you'll notice your article does not mention fast rotating stars.
Try reading a reference before you post it.

>>4503143
I don't think you understand what centripetal force is..

>>4503020
Because E=MC^2, kinetic energy is equivalent to mass, we see some strangeness.
As the disk. clouds, or planet. Accelerates, the fastest segment(the outer rim in a solid, rigid disc) would gain the most "energy/Mass", this in turn would mean their gravitational influence incresases to the point where they tear appart the middle section and, if perfectly balanced gravity-wise to retain shape, would leave you with a toroidal black hole(with some residual mass trapped floating in the center).

>>4503162
pulsars ie neutron stars.

but OP's question was about accretions of dust. not stars. these, if big enough, form supermassive black holes.

>>4503160
oops.. yea my bad, i confused it with centrifugal force, thanks

>>4503162
Frame Dragging = the rotation of a massive object distorts the spacetime metric, which in turn effects the massive object on said metric

How fucking slow are you? Are you literally fucking 12? GTFO! Troll?

>>4503169
yea i can picture that

>>4503180
>effects

>>4503180
As you'll note it's really isn't relevant for objects such as stars.

The only case this is relevant in is black holes. centripetal force is proportional to 1/(r^3) whereas gravity is proportional to 1/(r^2) so at small scales i.e. fast velocities centripetal force will dominate and the object will fly apart. Unless that object forms an event horizon first.
In this domain relativity would become significant and our lack of knowledge of the physics of black holes would show though.

>>4503169
>toroidal black hole

LMAFO. Nope.
Stop just making up bullshit.


http://en.wikipedia.org/wiki/Black_hole
Rotating black holes are surrounded by a region of spacetime in which it is impossible to stand still, called the ergosphere. This is the result of a process known as frame-dragging; general relativity predicts that any rotating mass will tend to slightly "drag" along the spacetime immediately surrounding it. Any object near the rotating mass will tend to start moving in the direction of rotation. For a rotating black hole this effect becomes so strong near the event horizon that an object would have to move faster than the speed of light in the opposite direction to just stand still.[66]

The ergosphere of a black hole is bounded by the (outer) event horizon on the inside and an oblate spheroid, which coincides with the event horizon at the poles and is noticeably wider around the equator. The outer boundary is sometimes called the ergosurface.

Objects and radiation can escape normally from the ergosphere. Through the Penrose process, objects can emerge from the ergosphere with more energy than they entered. This energy is taken from the rotational energy of the black hole causing it to slow down.

well the thread is dead, thanks ppl, i got many good answers, bye