If two objects traveling just below the speed of light collide, what happens?

[venk]

BY just below i mean the closest possible speed to the speed of light.

ie C - (1/x) as x approaches infinity.

Would it collapse the universe? Two nearly infinite (whatever that means) masses collliding?

 

[Calin]

They use highly accelerated particles to hit immobile targets. Protons near light speed (well, not really near light speed, but at a significant fraction of it), they have several times their mass at 0 speed.
What do they get? Usually very heavy elements (much after Uranium), very energic other particles and very low level particles (those so called "quarks", which are components of protons, electrons, neutrons)

 

[silverpig]

Originally posted by: Calin
They use highly accelerated particles to hit immobile targets. Protons near light speed (well, not really near light speed, but at a significant fraction of it), they have several times their mass at 0 speed.
What do they get? Usually very heavy elements (much after Uranium), very energic other particles and very low level particles (those so called "quarks", which are components of protons, electrons, neutrons)

Not quite. Heavy elements are created by smashing pre-existing nuclei together (firing iron nuclei at gold or something like that).

Protons at particle accelerators travel at about 99.9999% the speed of light when they collide. They produce a whole mess of particles like anti-protons, protons, muons, tau particles, neutrinos, W/Z bosons, Higgs(?) , and even more exotic particles like delta (++) etc... Basically, they produce quarks and leptons, but never bare quarks by themselves. The energy contained by the incident protons is used up in the form of mass for these new particles, most of which decay very quickly into photons and neutrinos.

 

[venk]

In the OP I was thinking more about Macro sized objects (ie two spaceships), not subatomic particles.

 

[icarus4586]

The mass of an object moving at speeds close to the speed of light is defined by:
(mass at speed near c) = (rest mass) / sqrt(1- (v^2)/(c^2))

With this equation, the speed of light acts as an asymptote, as velocity approaches c, mass approaches infinity. Graph showing this: http://www.rit.edu/~ntp0166/graph.jpg

Based on some calculations and information Google found me, you'd need a density of 6.49e18 kg/m^3 to become a "black hole."

If we assign both ships an arbitrary volume of 750 cubic meters, the combined mass would need to be 9.74e21 kg. My calculator isn't precise enough to calculate how close the required velocity would be.

So to answer your question, since it's impossible for anything with mass to achieve the speed of light, two somewhat large, somewhat massive objects travelling at the limit as x approaches zero of the speed of light minus x... would each create a black hole. IDK what happens when 2 black holes collide. Really big black hole?

 

[Vegitto]

When two black holes collide? I think they consume each other, and the fabric of time with it. Like a dragon, eating its own tail. When it's done, there's nothing left.

 

[Emultra]

Originally posted by: Vegitto
When two black holes collide? I think they consume each other, and the fabric of time with it. Like a dragon, eating its own tail. When it's done, there's nothing left.

Eh? And the conservation of energy?

 

[cquark]

Originally posted by: icarus4586
The mass of an object moving at speeds close to the speed of light is defined by:
(mass at speed near c) = (rest mass) / sqrt(1- (v^2)/(c^2))

With this equation, the speed of light acts as an asymptote, as velocity approaches c, mass approaches infinity. Graph showing this: http://www.rit.edu/~ntp0166/graph.jpg

Based on some calculations and information Google found me, you'd need a density of 6.49e18 kg/m^3 to become a "black hole."

If we assign both ships an arbitrary volume of 750 cubic meters, the combined mass would need to be 9.74e21 kg. My calculator isn't precise enough to calculate how close the required velocity would be.

So to answer your question, since it's impossible for anything with mass to achieve the speed of light, two somewhat large, somewhat massive objects travelling at the limit as x approaches zero of the speed of light minus x... would each create a black hole. IDK what happens when 2 black holes collide. Really big black hole?

Mass does not increase with velocity. Relativistic mass is not the same as mass. Objects do not collapse into black holes by accelerating near the speed of light.

If something's a black hole, it's a black hole in any reference frame. However, in your example, the object is a black hole in one reference frame, but in other reference frames it's not. In its own reference frame, its velocity is zero, so there's no additional relativistic mass to cause it to collapse into a black hole; however, in its reference frame, you are moving near the speed of light and hence should be a black hole by your argument.

As I've posted earlier on this forum, relativistic mass will mislead you in reasoning about special relativity in many ways, as Taylor and Wheeler point out in the classic text on relativity, Spacetime Physics:

"Ouch! The concept of `relativistic mass' is subject to
misunderstanding. That's why we don't use it. First, it applies the
name mass--belonging to the magnitude of a four-vector--to a very
different concept, the time component of a four-vector. Second, it
makes increase of energy of an object with velocity or momentum appear
to be connected with some change in internal structure of the object.
In reality, the increase of energy with velocity originates not in the
object but in the geometric properties of space-time itself."

or if you want an older authority, Einstein also made the same point:

"It is not good to introduce the concept of the mass M =
m/(1-v2/c2)^1/2 of a body for which no clear definition can be given.
It is better to introduce no other mass than `the rest mass' m.
Instead of introducing M, it is better to mention the expression for
the momentum and energy of a body in motion."

 

[cquark]

Originally posted by: Vegitto
When two black holes collide? I think they consume each other, and the fabric of time with it. Like a dragon, eating its own tail. When it's done, there's nothing left.

You get a single black hole, whose mass is equal to that of the two colliding black holes minus any lost during the collision.

 

[icarus4586]

Mass does not increase with velocity. Relativistic mass is not the same as mass. Objects do not collapse into black holes by accelerating near the speed of light.

If something's a black hole, it's a black hole in any reference frame. However, in your example, the object is a black hole in one reference frame, but in other reference frames it's not. In its own reference frame, its velocity is zero, so there's no additional relativistic mass to cause it to collapse into a black hole; however, in its reference frame, you are moving near the speed of light and hence should be a black hole by your argument.

Touche. I guess that's what I get for not having taken modern physics yet and relying pretty much entirely on Google.

 

[Calin]

Originally posted by: cquark

Originally posted by: Vegitto
When two black holes collide? I think they consume each other, and the fabric of time with it. Like a dragon, eating its own tail. When it's done, there's nothing left.

You get a single black hole, whose mass is equal to that of the two colliding black holes minus any lost during the collision.

"Lost" in the collision means transformed (and radiated) in energy

 

[MetalStorm]

I'm sick of these stupid threads. So to all those people with no grasp of physics and want to ask a stupid question; go to school.

Someone should have just answered "NO" and closed the thread.

 

[cecallred]

Originally posted by: MetalStorm
I'm sick of these stupid threads. So to all those people with no grasp of physics and want to ask a stupid question; go to school.

Someone should have just answered "NO" and closed the thread.

Arrogance doesn't look good on you. These threads are here for this and if you don't enjoy them, why not simply Not read them?

Your attitude was insulting to the person who asked the question, and to those who chose to answer and debate. I see no where that you contributed to this at all. If you have the correct answer, you could have chosen to teach instead of insult.

As the lead in to this thread says: "leave your egos at the door."

 

[Whoozyerdaddy]

I think you guys are missing the most obvious answer...

Both objects would be pulled into an alternate universe where they could eavesdrop on a private meeting between Elvis and the Easter Bunny. In that conversation it is discovered that, along with Jimmy Hoffa, they plan a hostile takeover of Starbucks with the intention of replacing my double mocha with... DECAF!!! Nooooooooooooooooooooooooooooooooooooooooooo.......

 

[MetalStorm]

Originally posted by: cecallred

Originally posted by: MetalStorm
I'm sick of these stupid threads. So to all those people with no grasp of physics and want to ask a stupid question; go to school.

Someone should have just answered "NO" and closed the thread.

Arrogance doesn't look good on you. These threads are here for this and if you don't enjoy them, why not simply Not read them?

Your attitude was insulting to the person who asked the question, and to those who chose to answer and debate. I see no where that you contributed to this at all. If you have the correct answer, you could have chosen to teach instead of insult.

As the lead in to this thread says: "leave your egos at the door."

I think my answer to the thread starter of "no" was quite informative actually; it certainly answered his question anyway.

I'm also aware of the "check your egos at the door" but don't you find it just a little annoying that people post pretty much the same questions time after time when they actually have no underlying knowledge of the subject? If they were to just read the other 1000 threads on the very same thing then that should curb their curiosity.

 

[Joepublic2]

You'd observe a strong gravitational wave as well, wouldn't you? I think these guys would notice what happened once it reached the earth.

http://www.ligo.caltech.edu/

 

[cquark]

Originally posted by: Joepublic2
You'd observe a strong gravitational wave as well, wouldn't you? I think these guys would notice what happened once it reached the earth.

http://www.ligo.caltech.edu/

Yes, the amount of energy that goes into gravitational radiation when two neutron stars collide is immense, and it should be similar for the collision of two black holes.

By the way, you can help out LIGO's search for gravitational waves by running their Einstein@Home software. You can read about it at
http://www.scienceblog.com/cms/node/7118
and get the software at
http://einstein.phys.uwm.edu/intro.php

 

[zachariahlogan]

Hello, I found this thread because I was thinking about this last night. Now, i have 0 physics background. But I like to think about it.

Now if you were to observe two copies of the same object, be it led for example. and the purpose of this illustration they would be bullets traveling at just under the speed of light, what would the collision look like.

Now, if the speed of light could 100% not be surpassed by our hypothetical collision, then you would be able to measure the energy of the collision and it would have to be equal to the mass of both bullets.

If it is not equal, one must logically think. Where did the other mass go?

Well, I was thinking- if the energy of the collision is not equal to the mass of the bullets right before the collision, does this mean the mass dissapeared - or simply could not be observed.

If as a result of the collison, the particles released as a result of the collision, exceeded the speed of light, as the though experiment suggests, is it possible the energy or particles were released before the collision?

If this is true- does this mean, the particles as a result of the collision infact were lost before the collision, and can thusly be classified as time travel. Of course only if you could find the energy or particles before and after they are lost.

Now I was thinking about a way to experiment with this.
If photons, both pass through eachother, and also interact with eachother- why can't we then set up two clone copies of lasers pointed perfectly at eachother in a way to make the light colide. Now if we let this experiment run for 10,000 years what would we find?

If the hypothesis was true, we could observe at the point were the two lasers colide would occasionally be dimmer, or occasionally be brighter than it should be.

If the thought experiment fails then the the amount of light producted at the collision of the two laser beams would be exactly constant for 10,000 years.

As mentioned this was something I was just thinking about in bed as I was falling asleep, and I have absolutely 0 background in physics or calculus. But I would really enjoy reading what you have to say.

Thank you
-Zach Logan

 

[Paul98]

Hello, I found this thread because I was thinking about this last night. Now, i have 0 physics background. But I like to think about it.

Now if you were to observe two copies of the same object, be it led for example. and the purpose of this illustration they would be bullets traveling at just under the speed of light, what would the collision look like.

Now, if the speed of light could 100% not be surpassed by our hypothetical collision, then you would be able to measure the energy of the collision and it would have to be equal to the mass of both bullets.

If it is not equal, one must logically think. Where did the other mass go?

Well, I was thinking- if the energy of the collision is not equal to the mass of the bullets right before the collision, does this mean the mass dissapeared - or simply could not be observed.

If as a result of the collison, the particles released as a result of the collision, exceeded the speed of light, as the though experiment suggests, is it possible the energy or particles were released before the collision?

If this is true- does this mean, the particles as a result of the collision infact were lost before the collision, and can thusly be classified as time travel. Of course only if you could find the energy or particles before and after they are lost.

Now I was thinking about a way to experiment with this.
If photons, both pass through eachother, and also interact with eachother- why can't we then set up two clone copies of lasers pointed perfectly at eachother in a way to make the light colide. Now if we let this experiment run for 10,000 years what would we find?

If the hypothesis was true, we could observe at the point were the two lasers colide would occasionally be dimmer, or occasionally be brighter than it should be.

If the thought experiment fails then the the amount of light producted at the collision of the two laser beams would be exactly constant for 10,000 years.

As mentioned this was something I was just thinking about in bed as I was falling asleep, and I have absolutely 0 background in physics or calculus. But I would really enjoy reading what you have to say.

Thank you
-Zach Logan

No.

If you want to understand physics actually learn about it. There are plenty of good places online. Making wild speculations on something you have no understanding of is useless. Start learning about relativity. Go into it with an open mind and don't try to make it into what you think it should be. Don't assume what you think you know or understand is true because it most likely isn't. How the universe works is much stranger than what we see around us. Make sure you really understand why things work the way they do, not just read something and remember what is says.

 

[Paul98]

BY just below i mean the closest possible speed to the speed of light.

ie C - (1/x) as x approaches infinity.

Would it collapse the universe? Two nearly infinite (whatever that means) masses collliding?

I would suggest you use an velocity and mass, for the most part you will get a huge explosion.

 

[Gibsons]

A fun read, on the subject of high velocity collisions
https://what-if.xkcd.com/20/

 

[SOFTengCOMPelec]

If two objects traveling just below the speed of light collide, what happens?

My understanding is that this will indeed cause an approx (20%) increase, beyond the speed of light.

I've done all the calculations, and if they are correct, it will also cause a spontaneous worm hole to open up, for just 1.2 pico seconds.

For anyone not familiar with the latest laws of physics, it is now known that even mentioning (in theory) this worm hole, will cause this thread to time jump, by about 9 years (into the past).

Lets check out this theory...

EDIT (28th July 2005): (NOT to be confused with the theory of relativity), on a non-joking manner. It is called the theory of Necrotivity, by Professor Harvey.

 

[mistersprinkles]

I think if two ships travelling near the speed of light collide, they will ricochet off eachother and keep flying because the ships will be made of adamantium. And nothing can break adamantium.

 

[SOFTengCOMPelec]

I think if two ships travelling near the speed of light collide, they will ricochet off eachother and keep flying because the ships will be made of adamantium. And nothing can break adamantium.

I hate disagreeing (especially with the highly technical aspects of this) with fellow posters, but I feel I MUST in this case.

The collision, tends to cause tiny fragments, which are close enough to a bullet like shape, to actually micro-break the material, and cause its destruction.

the original comics revealed adamantium was penetrable by bullets made of the same alloy.

Linked proof, here.

 

[nOOky]

I don't really know how to answer the OP's question without getting too involved, but simply stated there will be a big bang and stuff.

I almost observed this happening this a.m. at work. An employee placed a box of doughnuts on a table by the cube farm, and two 400 pounders each made for the box at near the speed of light. The resulting collision decimated the cube farm, there was fat everywhere. If you think I'm joshing there's a real video on Liveleak, I swear.

Now practically I have always thought that using an inert object, and accelerating it to as fast a speed as humanly possible (at the current technology level) is the best way to defeat a wayward asteroid etc. from hitting the Earth.