What Happens If an Object Exceeds the Speed of Light?

[Cajun]

Is it possible to have an object bigger than the speed of light? What would an object that was hundreds of thousands light years across look like? Is there a point in which forces acting on it would make it impossible? Like gravity turning it into a black hole? I am interested in the Great Attractor and the possible cause of Galaxies moving in a single direction at +700 km/s. Could a mass just grow and grow to such a size to cause galaxies to become gravitationally attracted to it?

 

[russ_watters]

Welcome to PF.

The question doesn't make sense - the units are different: speed isn't distance.

 

[Nabeshin]

Is it possible to have an object bigger than the speed of light?

This question doesn't even make any sense. The speed of light is a speed, in units of length per time. No matter how you measure the "bigness" of an object, it's either some power of length or mass, so the dimensions do not even match up.

Masses can and do just grow and grow because of gravity. Indeed, that's how all large scale structure began in our universe. Small overdensities over time accumulated more matter and eventually clumped into galaxies and clusters of galaxies.

If this doesn't answer your question, could you clarify?

 

[Cajun]

Ya, Bigger that the speed of light was a bad choice of words. What i mean is just an object so massively big that it takes light hundreds if not thousands of years for light to travel across its surface...a galactic deathstar lol. Could an object that big have effects on other galaxies to the point they move towards it?

 

[russ_watters]

An object can't be that big - it would collapse on its own gravity and become a black hole long before.

 

[Cajun]

At what point? Could there be a way to manipulate the size vs the mass to overcome the effects of collapsing on its own gravity?

 

[Cajun]

But if it didnt collapse under its own gravity...it couldn't effect other galaxies?

 

[russ_watters]

Try this: http://en.wikipedia.org/wiki/Type_Ia_supernova

In any case, gravity is a cumulative thing anyway: galaxies attract other galaxies.

 

[Nabeshin]

It's not clear to me at all what you mean by "Object". As far as a cosmologist is concerned, galactic clusters are objects, It takes light millions of years to cross these.

Also, it doesn't matter how massive an object is -- everything attracts everything else. I am right now, as we speak, attracting the Andromeda galaxy towards us. The magnitude of the effect is just pitifully small. So your question is really one of magnitude -- you want to affect changes appreciably in galactic motion. Well, the mass scale for something like this is quite simple -- the mass of the galaxy. So you would need to have an object some ~10^40 kg massive.

 

[Khursed]

I'll try to give an answer that adress what you say.

First of all the biggest physical object I know of, is http://en.wikipedia.org/wiki/VY_Canis_Majoris we're talking an object that if put in the middle of the solar system would engulf the sun and all the planets up to saturn and a bit further.

However, such an object that weights in at close to 30-40 times the sun, is extremely tenuous, we're talking about a star who's density is incredibly small, thus the problem of accurately measure it, since at some point we're basically trying to measure an object that is less dense then a fly's fart in space.

Such an object measures close to 1,7 billion miles, and it would require light over 2 and a half hrs to go across, and nearly 5 hrs to go around it.

Considering how massive it is and its awesome radiation, you might want to be further away from it when you go around it tho :)

The main problem with any "stellar scale" structures, that you would find in science fiction, since we can't build them atm, is that you always encounter the same barrier, the torque, the forces and the stress impossed on the structures invariably call for material with strength and specific requirements completely out of this world, and far far beyond even our best possible technologies.

Consider just a ring world, not a full scale Dyson sphere, but just a belt built around a sun, for example this...

http://en.wikipedia.org/wiki/Ring_world

When you want to conceptualise such structures, you always find that the laws of science and the capacity of our technology simply can't allow for such object.

As far as a natural object, like i said, the biggest physical one are massive stars, otherwise, there's the lyman-alpha blob and forest are on a scale completely breath taking, but its not very tangible as far as object goes :)

Hopefully I answered your question a little.

 

[Cajun]

To better understand what I am asking, maybe its better to ask in the context of why I am asking this question. I am writing a science fiction book in which a species exists that is so powerful they start "collecting" all the matter in the universe and bringing it to one place to build a galactic computer. Besides the obvious amount of energy required to move matter across the universe, would it be possible to have a race that is intelligent enough to build an object that massive? The Wikipedia article on Type Ia supernova about electron degeneracy pressure kinda answered my question, but i don't understand the technical part of it. Is there away around it, like by not having all the matter touching enough to force a collapse? Also what do you mean by gravity is cumulative, meaning all the mass in a galaxy add to its overall gravitational pull? "I am right now, as we speak, attracting the Andromeda galaxy towards us." Could you explain that a little better? I once heard a theory about electromagnetic "Ropes" coming from every electron in the universe and attaching to every other electron in the universe, and these ropes cause gravity, is that what you mean?

 

[Drakkith]

You could always just have them invent some device that reduces the force from gravity. That would result in no black hole being formed.

And the electromagnetic ropes are something I've never heard of and wouldn't make any sense anyways since electrons repel each other.

Also what do you mean by gravity is cumulative, meaning all the mass in a galaxy add to its overall gravitational pull? "I am right now, as we speak, attracting the Andromeda galaxy towards us."

You are correct on both parts. Your individual mass is extremely miniscule compared to the mass of the entire galaxy, but it all adds up you know.

 

[DaveC426913]

Is there away around it, like by not having all the matter touching enough to force a collapse?

Yes, keep the density down.

Also what do you mean by gravity is cumulative, meaning all the mass in a galaxy add to its overall gravitational pull? "I am right now, as we speak, attracting the Andromeda galaxy towards us." Could you explain that a little better?

Quite literally what he said.

All mass attracts all other mass in the universe proportional to its mass and inversely proportional to the square of its distance.

The atoms in your body exert a gravitational pull (albeit vanishingly small) on the Andromeda galaxy. However, while vanishingly small, it is cumulative. You, the Earth, Sol and 500 billion other stars are all part of the Milky Way Galaxy and we are pulling on Andromeda.

 

[Cajun]

You could always just have them invent some device that reduces the force from gravity. That would result in no black hole being formed.

I don't believe gravity to be a "force" at least not like electromagnetism. I believe it to be an emergent phenomenon that's comes from spacetime itself.
http://en.wikipedia.org/wiki/Entropic_gravity
Looking at it like this seems like we will never escape gravity.

And the electromagnetic ropes are something I've never heard of and wouldn't make any sense anyways since electrons repel each other.

He has some interesting theories.
Electromagnetic ropes.
http://www.youtube.com/user/bgaede#p/u/20/J-NB5vg7woM
Gravity.
http://www.youtube.com/user/bgaede#p/u/16/i7QmsngMRpE

 

[Cajun]

Yes, keep the density down.

So let's say it resembled a huge sponge, only individual parts touching each other with empty spaces in between? Or do you mean the density of the material, as in aluminum is less dense than steel?

Quite literally what he said.

All mass attracts all other mass in the universe proportional to its mass and inversely proportional to the square of its distance.

The atoms in your body exert a gravitational pull (albeit vanishingly small) on the Andromeda galaxy. However, while vanishingly small, it is cumulative. You, the Earth, Sol and 500 billion other stars are all part of the Milky Way Galaxy and we are pulling on Andromeda.

Im amazed that The Great Attractor is massive enough to attract all those galaxies? So the best possible explanation would be a HUGE black hole since anything that massive would probably collapse into one?

"Attractor was actually only one tenth the mass that scientists had originally estimated. The survey also confirmed earlier theories that the Milky Way galaxy was in fact being pulled towards a much more massive cluster of galaxies near the Shapley Supercluster which lies beyond the Great Attractor.."
http://en.wikipedia.org/wiki/The_Great_Attractor

 

[Nabeshin]

SSo the best possible explanation would be a HUGE black hole since anything that massive would probably collapse into one?

Not at all. Take galaxies for example. They have the largest black holes known at their centers, but yet the mass of the black hole accounts for only a small percentage of the total mass -- most of it is in stars and gas. So larger structures composed of galaxies, say a cluster of 100 galaxies, has a very small portion of that total mass comprised of black holes. You can then make a cluster of clusters of galaxies, or a supercluster, with larger mass still. This is roughly (roughly) the mass range we're talking about with the great attractor.

Moral of the story: Just because something is massive does not at all mean it must be a black hole.

 

[DaveC426913]

So let's say it resembled a huge sponge, only individual parts touching each other with empty spaces in between? Or do you mean the density of the material, as in aluminum is less dense than steel?

Either way. If the structure can support its own weight - such that it does not collapse to degenerate matter and then have its individual atoms crushed into a singularity, then it won't create a black hole.

 

[Khursed]

To better understand what I am asking, maybe its better to ask in the context of why I am asking this question. I am writing a science fiction book in which a species exists that is so powerful they start "collecting" all the matter in the universe and bringing it to one place to build a galactic computer. Besides the obvious amount of energy required to move matter across the universe, would it be possible to have a race that is intelligent enough to build an object that massive? The Wikipedia article on Type Ia supernova about electron degeneracy pressure kinda answered my question, but i don't understand the technical part of it. Is there away around it, like by not having all the matter touching enough to force a collapse? Also what do you mean by gravity is cumulative, meaning all the mass in a galaxy add to its overall gravitational pull? "I am right now, as we speak, attracting the Andromeda galaxy towards us." Could you explain that a little better? I once heard a theory about electromagnetic "Ropes" coming from every electron in the universe and attaching to every other electron in the universe, and these ropes cause gravity, is that what you mean?

All the matter implies a stagering amount of energy, also, why such a big computer? I mean once you've used all the matter in the universe, you've got a big computer, and a few alien playing the fastest game of pong ever!

BTW, you could always set up your computer in such a way as to have the mass of it not being compact, such as building it in a way that the massive pieces are all in orbit around each other, and placed in such a way as to balance the gravitational forces.

So imagine a multi-core mega universe computer, you start by having your race create CPU out of neutron stars, you attach multiple co-processor of Jupiter size in orbit around it to gather and input data. Then you have black holes being fed constant matter to power it all, and massive Dyson belt of data storage in orbit around it all.

If you can balance it all, it doesn't have to all be in one big clump, and since your hypethetic race is bringing all this matter in one spot, I'm assuming they can re-arrenge matter at will.

So, balancing it all, so you don't collapse it all, should be child's play after doing the heavy lifting.

You could build it all like a galaxy, but built closer and to a higher degree of compactness.

 

[Cajun]

All the matter implies a stagering amount of energy, also, why such a big computer? I mean once you've used all the matter in the universe, you've got a big computer, and a few alien playing the fastest game of pong ever!

Well this is a story about our universe (what came before during and after). After the big bang the universe goes through several stages of intelligence. We are currently about halfway through the third cycle in which we are building the next intelligent creature in line to rule over the universe. On the sixth cycle the need for individual existence becomes not only illogical, but impossible. Its at this point the so called machines do pretty much the only thing they have been good at, and the only thing left to do. Collect information and grow bigger. What would the borg do after the assimilated everything? Recycling and renewal of energy and entropy are big themes in the book, and the stagering amount of energy they use to accomplish this comes with a paradoxical price.

BTW, you could always set up your computer in such a way as to have the mass of it not being compact, such as building it in a way that the massive pieces are all in orbit around each other, and placed in such a way as to balance the gravitational forces.

Hmm, think about an egg. Why is the egg so strong? Maybe they find a shape that's just geometrically perfect? What about a gyroscope, everything orbiting around a center with perfect balance between the forces?

 

[Subluminal]

Cajun I'm a big fan of sci fi but as I age I find myself more disappointed at the implausibility authors inevitably use in technical explanations, such as what dilithium crystals are or how they work. Maybe writers have access to too many special effects these days for their own good. I most enjoy near-future stories that exploit recent discoveries or use possible though improbable quantum events, and tell a good story without the distracting need to re-invent physics. Killer clones, a particle accelerator mishap, a meteorite that turns Stephen King into a fuzzy green monster - it's all good.

The characters in your story about such a massive machine would encounter some interesting effects on how time changes relative to how people far away from the machine (or distant points within it) observe time. Signals eminating from the center would be red shifted, infalling signals would be blue shifted. Read up on GPS satellites and GR. Also, I think Einstein demonstrated how gravity itself does not travel faster than light. So, if a black hole hurtles past us toward some Great Attractor we are pull toward the black hole, but aren't we really just being pulled to some point where it used to be a long time ago? I imagine our whole galaxy is a bunch of smaller galaxies mixing together as we chase down our fleeting black hole, but we have no hope of ever catching up to it due to this gravitational time lag and it's always accelerating to its destination, which is likely also moving and leaving a similar ghostly attractor in its wake, too. OK, got a little rambly there.

 

[DaveC426913]

Cajun I'm a big fan of sci fi but as I age I find myself more disappointed at the implausibility authors inevitably use in technical explanations, such as what dilithium crystals are or how they work. Maybe writers have access to too many special effects these days for their own good.

"these days?" What? Dilithium crystals are almost a half century old.

 

[Cajun]

Cajun I'm a big fan of sci fi but as I age I find myself more disappointed at the implausibility authors inevitably use in technical explanations, such as what dilithium crystals are or how they work. Tell a good story without the distracting need to re-invent physics.

This book is not about how but about why. I want to use everything we know in science and fill in the blanks about things we can't possibly know. What came before the big bang? What is the purpose of life? Is there a God? Plausibility is what i want. But i agree, its about the story telling, not what dilithium crystals do or how they power the ships, or where they get anti-matter. Its about the why. Two problems I've encountered are the problems with masses that big and inflation/expansion. I have another thread to help with inflation.

The characters in your story about such a massive machine would encounter some interesting effects on how time changes relative to how people far away from the machine (or distant points within it) observe time. Signals eminating from the center would be red shifted, infalling signals would be blue shifted. Read up on GPS satellites and GR.

Ive thought about that, if we looked in the star and saw an object the size of hundreds of thousands of galaxies, what would it look like from far away or even on its surface? Like the surface of Earth going on past the solar system? I understand red/blue shift when i comes to the expansion of the universe, but let's say we were using entangled photons for a quantum computer (just read a great article on our first photon entanglement and its use in quantum computers http://www.research.att.com/articles/featured_stories/2010_12/201101_Entangled_photons.html), what would red/blue shift do to the computer processes? Faster information going outward but not inward? Ya, I am impressed by the timing signals we use for the satellites, to think about the combined human effort we put into GPS.

Also, I think Einstein demonstrated how gravity itself does not travel faster than light. So, if a black hole hurtles past us toward some Great Attractor we are pull toward the black hole, but aren't we really just being pulled to some point where it used to be a long time ago? I imagine our whole galaxy is a bunch of smaller galaxies mixing together as we chase down our fleeting black hole, but we have no hope of ever catching up to it due to this gravitational time lag and it's always accelerating to its destination, which is likely also moving and leaving a similar ghostly attractor in its wake, too. OK, got a little rambly there.

Can black holes move, or be accelerated to high speeds? Every time i read or see a black hole on video its stationary. Unless the black hole was moving faster than the speed of light, wouldn't we fall towards it still and eventually get sucked in? If it was moving faster than the speed of light, would we just be forever moving towards an unknown destination never to know what is causing the pull?

 

[Khursed]

This book is not about how but about why. I want to use everything we know in science and fill in the blanks about things we can't possibly know. What came before the big bang? What is the purpose of life? Is there a God? Plausibility is what i want. But i agree, its about the story telling, not what dilithium crystals do or how they power the ships, or where they get anti-matter. Its about the why. Two problems I've encountered are the problems with masses that big and inflation/expansion. I have another thread to help with inflation.



Ive thought about that, if we looked in the star and saw an object the size of hundreds of thousands of galaxies, what would it look like from far away or even on its surface? Like the surface of Earth going on past the solar system? I understand red/blue shift when i comes to the expansion of the universe, but let's say we were using entangled photons for a quantum computer (just read a great article on our first photon entanglement and its use in quantum computers http://www.research.att.com/articles/featured_stories/2010_12/201101_Entangled_photons.html), what would red/blue shift do to the computer processes? Faster information going outward but not inward? Ya, I am impressed by the timing signals we use for the satellites, to think about the combined human effort we put into GPS.



Can black holes move, or be accelerated to high speeds? Every time i read or see a black hole on video its stationary. Unless the black hole was moving faster than the speed of light, wouldn't we fall towards it still and eventually get sucked in? If it was moving faster than the speed of light, would we just be forever moving towards an unknown destination never to know what is causing the pull?

Black hole are not imoveable object, they obey gravity as any other object, they simply become different when you get very close to them, otherwise, they are indistinguishable from any other heavy object.

Say a heavy star a couple light years goes super nova and ends up as a 12 solar mass black hole, we wouldn't all sudenly be incredibly attracted toward it because now the massive star is a black hole.

You could replace the moon by a black hole, and nothing much would change on earth. Same for the sun, beside the nasty lack of life giving light :P

Thing is, black hole have been overly portrayed as nightmarish matter sucking oblivion machine. When in fact, a black hole just can't do much beside wait for stuff to make its way there, otherwise it doesn't gain increased gravity to attract far off matter.

To answer your question, yes they could be accelerated to very high speed, such as a galaxy merger bumping one out of them at extremely high speed, same principle as for any star being expulsed from a galaxy due to orbital shift, or the like.

I don't believe a black hole could go faster then the speed of light, however if it did, I can't possibly be sure, however I would surmise it wouldn't affect us much, seeing as gravity answers to the reverse square law, and that would mean it would be unlikely to affect us much. Well, that is if it doesn't move through our solar system at those speed, otherwise, say a 2-12 solar mass black hole would pretty much ruin our day in a spectacular fashion that is hard to imagine.

 

[DaveC426913]

Can black holes move, or be accelerated to high speeds?

As Khursed points out, at a distance they're much like any other massive body. They obey the law of gravity.

Black holes can gain a charge if you drop enough ionized matter into them. Some speculative science fiction writers riff on this to use giant magnetic fields as black hole manipulators.

Every time i read or see a black hole on video its stationary.

Because details of its movement are unremarkable.

Unless the black hole was moving faster than the speed of light,

Nope. Bzzt.

wouldnt we fall towards it still and eventually get sucked in?

No more than any other massive body.

As Khursed points out, if the Moon were to suddenly collapse into a black hole, it would have no effect on the tides.

 

[Nick666]

This topic reminds me of this http://www.spacerat.meteornet.net/blog/wp-content/uploads/2010/10/ftl.png

 

[Subluminal]

There's matter and energy, which seem distinct but are interchangeable. Then there's space and time, apparently different but also connected in a way that obeys conservation. What in the universe is made of something other than these four things? Everything appears to be a combination of these, call them "elements". Then there's gravity - the quintessence, the ambrosia. Tied to matter, converting potential to kinetic energy, reaching across vast distances and warping time itself. It has to be something, but without the other four things it would have no purpose or existence. Maybe it requires a massive supercomputer to figure it out, but I'm hopeful our little monkey brains might actually be equipped to make some sense of it.

2012 is coming, and with it an event that will no doubt reveal some answers and even more questions. A complete download of the known universe into our heads, from a new satellite that makes the Hubble look like a dirty old pair of binoculars. I can't wait.

 

[Cajun]

This topic reminds me of this http://www.spacerat.meteornet.net/blog/wp-content/uploads/2010/10/ftl.png

Yes, anyone have any thoughts on that picture. I've been looking for an answer to that question. Would spacetime be warped to such a point that pushing on one end would bend and stretch the rod enough to prevent faster than light communication? Or would the atoms that make up it be compressed into a almost light speed wave ripple through the metal?

 

[JaredJames]

Everything appears to be a combination of these, call them "elements".

No, don't. They are not.

Tied to matter, converting potential to kinetic energy,

Without gravity you wouldn't have gravitational potential energy - clues in the name. It doesn't just "convert".

Maybe it requires a massive supercomputer to figure it out

Computers only do what we tell them. If we don't know the maths for it, no computer can run it.

2012 is coming,

One would hope so, or this calendar is going back.

and with it an event that will no doubt reveal some answers and even more questions. A complete download of the known universe into our heads, from a new satellite that makes the Hubble look like a dirty old pair of binoculars. I can't wait.

And now you drop completely out of reality. Complete non-sense that doesn't belong on this forum.

 

[JaredJames]

Yes, anyone have any thoughts on that picture. I've been looking for an answer to that question. Would spacetime be warped to such a point that pushing on one end would bend and stretch the rod enough to prevent faster than light communication? Or would the atoms that make up it be compressed into a almost light speed wave ripple through the metal?

Shockwaves travel at the approximately speed of sound through a medium. Either way, significantly less than the speed of light.

That 'rod' idea came up in another thread here - no doubt this picture was the source for it.

I believe that the universe is made of 8 elements. Space and Time. Matter and Energy. Soul and Spirit. Logic And Love. Logic would be what we call dark energy, the tendency for things to separate. Love would be gravity, the force that makes things attract each other.
This wavelength oscillates between logic and love, the more logic in the universe, the less love.

Again, as per above this is just non-sense. Putting your own descriptions on things doesn't mean anything. Leave it out.

Not even God himself is above these laws (if you really think about what it would be like to be God).

Leave this out too.

I can't think of anything that can be described without give and take.

There are a lot of things that can.

Nor do i believe in solar flares,

They are scientific facts - we have pictures of them - there's nothing to "not believe" in.

aligning of the planets

It happens.

the galactic equator

It exists.

I assume with the above you are referring to specific 2012 phenomena. In which case I'd let you off.

What i do believe about 2012 is not an "event" but an awakening. I can see it in the world, just read the news. We have reached a peak of logic in the world. But underneath the chaos of the world they have created, i see a growing trend of people willing to see past the lies of the world and the corner of corruption society has backed itself into. The internet is the next phase of intelligence but compared to a human, its still learning how to visualize and perceive the world. Sadly i do no believe it is our role in the universe to download the known universe, but it is our role to create the next life form that does. The final outcome would be a civilization that is "Bigger than the speed of light"

And we're out of reality again. Leave it out, it doesn't belong here.

 

[Subluminal]

The metal rod thing could easily be tested since we've been able to directly measure the speed of light in a lab for over 100 years and getting better at it ever since. A 2ly long rod connecting comoving planets would still have some other issues to work out obviously.

I'm glad I got a big juicy nibble on my 2012 joke. Of course I was referring to the date when the Planck Spacecraft, launched years ago by the ESA, provides us with its first complete sky survey. I thought this forum might be the correct place to discuss data from the Planck, but maybe our little monkey brains aren't as ready as I'd hoped.

 

[JaredJames]

The metal rod thing could easily be tested since we've been able to directly measure the speed of light in a lab for over 100 years and getting better at it ever since. A 2ly long rod connecting comoving planets would still have some other issues to work out obviously.

What's there to test? We know how fast shock waves travel. We know exactly what would happen with such a rod. It certainly wouldn't be ftl communication.

I'm glad I got a big juicy nibble on my 2012 joke. Of course I was referring to the date when the Planck Spacecraft, launched years ago by the ESA, provides us with its first complete sky survey. I thought this forum might be the correct place to discuss data from the Planck, but maybe our little monkey brains aren't as ready as I'd hoped.

If it's valid research then it's fine, but attempting to subtly insult the people here is not.

 

[Subluminal]

Get over yourself! The writings of Galileo, Einstein and many other respected scientists are loaded with thinly veiled insults towards those who disagreed with them. Since you enjoy doing it too, consider yourself in good company.

 

[JaredJames]

Get over yourself! The writings of Galileo, Einstein and many other respected scientists are loaded with thinly veiled insults towards those who disagreed with them. And if you enjoy doing it too, consider yourself in good company.

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[Cajun]

Originally Posted by Subluminal

"The characters in your story about such a massive machine would encounter some interesting effects on how time changes relative to how people far away from the machine (or distant points within it) observe time. Signals eminating from the center would be red shifted, infalling signals would be blue shifted. Read up on GPS satellites and GR."

Ive thought about that, if we looked in the star and saw an object the size of hundreds of thousands of galaxies, what would it look like from far away or even on its surface? Like the surface of Earth going on past the solar system? I understand red/blue shift when i comes to the expansion of the universe, but let's say we were using entangled photons for a quantum computer (just read a great article on our first photon entanglement and its use in quantum computers http://www.sciencedaily.com/releases/2011/01/110120111039.htm), what would red/blue shift do to the computer processes? Faster information going outward but not inward? Ya, I am impressed by the timing signals we use for the satellites, to think about the combined human effort we put into GPS.