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Author Topic: If light is the fastest thing in the universe why do black holes suck it in?  (Read 601 times)

Offline thedoc

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Paul asked the Naked Scientists:
   If light is the fastest thing in the universe why do black holes suck it in? Gravity inside a black hole is far superior. This will be the force that allows us to travel faster than light (FTL). If gravity is more than light we will use gravity drive to reach stars at warp speed not light speed
What do you think?
« Last Edit: 06/10/2016 20:53:02 by _system »


 

Offline evan_au

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Quote from: Paul
If light is the fastest thing in the universe why do black holes suck it in?
Because the escape velocity of a black hole exceeds the speed of light.

Quote
This will be the force that allows us to travel faster than light (FTL). If gravity is more than light we will use gravity drive to reach stars at warp speed not light speed
There are a number of speculative ideas about how Faster Than Light travel might be achieved - Hollywood is paying a lot of attention, and even NASA is not ignoring them.

It is thought that if you take a certain path around a black hole, it may be possible to survive the journey, and end up somewhere else in space.
A wormhole is another theoretical concept that might allow FTL, see https://en.wikipedia.org/wiki/Wormhole.

A more controlled concept is the Alcubierre drive, see https://en.wikipedia.org/wiki/Alcubierre_drive

But personally, I would not be too worried if the nearest black hole was far away from Earth. Because the most likely outcome for something approaching a black hole is for it to be ripped apart, ground to dust, heated to a searing plasma and then swallowed, never to see the stars again.
 

Offline Bill S

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Quote from: Paul
If light is the fastest thing in the universe why do black holes suck it in?

Have a care with the idea that black holes suck.

 

Offline zx16

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Black Holes don't suck, they just take whatever they can get.
 

Offline chris

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Paul asked the Naked Scientists:
If light is the fastest thing in the universe why do black holes suck it in?

Just to elaborate on Evan's point, black holes are a highly dense aggregation of matter. This means that, in their vicinity, they are highly gravitationally active, which means that they bend spacetime in such a way that incident light is funneled in. Not all passing light is swallowed, however. The path of light passing close by, but not inside the envelope of the black hole's event horizon, will be curved. This is the phenomenon referred to as "gravitational lensing" and was first documented by Arthur Eddington on an expedition in 1919 to test Einstein's 1915 theory of general relativity.

The wiki page on this is well-written and worth a look: https://en.wikipedia.org/wiki/Gravitational_lens 
 

Offline zx16

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Can a photon in a light-ray which is approaching a black hole, be neither swallowed not deflected - but captured into an orbit around the hole.

In the same way that an object approaching the Earth, can (if it's on exactly the right trajectory) be captured into orbit around the Earth.

If photons can be captured in this way, won't there be huge swarms of them orbiting every black hole?  What will their optical effect be, I mean will they form a kind of halo of light around the hole?





 

Offline jeffreyH

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Can a photon in a light-ray which is approaching a black hole, be neither swallowed not deflected - but captured into an orbit around the hole.

In the same way that an object approaching the Earth, can (if it's on exactly the right trajectory) be captured into orbit around the Earth.

If photons can be captured in this way, won't there be huge swarms of them orbiting every black hole?  What will their optical effect be, I mean will they form a kind of halo of light around the hole?

At a critical distance from a black hole there is what is known as the photon sphere. This is the distance at which the speed required to maintain an orbit is the speed of light. Once a photon has entered this orbit it is trapped. This means that it cannot be detected at remote distances. So a halo of light will not be visible away from the photon sphere.

Also the photons in this region would be blue shifted out of the visible spectrum.
 

Offline AndroidNeox

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The simple answer is, they don't.

Einstein was right that event horizons cannot form. Before an event horizon can form, an infinite amount of time will pass for all of the universe. There hasn't been time, yet, for any event horizons to form. In 100 trillion years there still won't have been enough time.

The measureable distance from any point in space to any event horizon is infinite. Not even light can travel from any point in space to an event horizon in finite time.
 
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Offline jerrygg38

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Can a photon in a light-ray which is approaching a black hole, be neither swallowed not deflected - but captured into an orbit around the hole.

In the same way that an object approaching the Earth, can (if it's on exactly the right trajectory) be captured into orbit around the Earth.

If photons can be captured in this way, won't there be huge swarms of them orbiting every black hole?  What will their optical effect be, I mean will they form a kind of halo of light around the hole?

At a critical distance from a black hole there is what is known as the photon sphere. This is the distance at which the speed required to maintain an orbit is the speed of light. Once a photon has entered this orbit it is trapped. This means that it cannot be detected at remote distances. So a halo of light will not be visible away from the photon sphere.

Also the photons in this region would be blue shifted out of the visible spectrum.
  The photon's ruler shrinks and it absorbs energy from the black hole. At the same time the photon's clock slows. To escape it must lose energy which is cannot do. Thus it exists in a world of part matter and part photon. and then it collides with another photon and produces matter/antimatter and then photons again. Thus the black hole continually eats everything up. Not a very pleasant place to be.
 

Offline yor_on

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Don't know.

About gravity being 'faster' than lights speed in a vacuum that is. Recently saw this idea of entangled quarks creating 'tunnels' that allowed them to do 'ftl', sort of :) what that means is just the same as with any entangled pair, you measure one and the other will then instantly  'know' what it showed, and so be in a 'opposite' reaction/position.

I found it a fascinating idea. We're so used to think of in terms of geometry though, but to me it speaks of something not related to our geometry at all, although the end result should be SpaceTimes geometry.
=

Gravity is not 'energy', although you can use it to gain energy from work done before.
And 'Inertia' is a instant reaction, as far as I know, and you don't need any 'gravitational potential' being present for inertia to act. You just need a 'acceleration/course change'


"Using holographic duality, Sonner derived the entangled quarks, and found that what emerged was a wormhole connecting the two, implying that the creation of quarks simultaneously creates a wormhole. More fundamentally, the results suggest that gravity may, in fact, emerge from entanglement. What's more, the geometry, or bending, of the universe as described by classical gravity, may be a consequence of entanglement, such as that between pairs of particles strung together by tunneling wormholes."


« Last Edit: 24/10/2016 21:03:01 by yor_on »
 

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