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Xorpd!

Joined: 21 Dec 2006
Posts: 161
Xorpd!
Thomas, perhaps you could check my arithmetic here.
If one particle has rest energy mc² and is at rest obviously it has total energy E[1] = mc² and momentum pc[1] = 0. The incoming particle has total energy E[2] ≈ 1e20 eV, rest energy mc² and so total momentum pc[2] = √(E[2]²-(mc²)²).
Adding these up we get a total energy of E[2]+mc² and momentum of √(E[2]²-(mc²)²), so rest energy of the system will be Mc² = √((E[2]+mc²)²-(E[2]²-(mc²)²)) = √(2(E[2]+mc²)(mc²)) ≈ √(2E[2]mc²).
Given E[2] ≈ 1e20 eV, mc² ≈ 1e9 eV, we have Mc² ≈ 4.47e14 eV. Two particles with equal and opposite momenta and total energies of 1e12 eV will clearly have a rest energy of 2e12 eV so it seems that we still have a factor of safety of about a couple of hundred here.
But what would be the Scharzschild radius of a cosmic ray induced black hole?
I get R = 2MG/c² = 2(4.47e14 eV)(1.602e-19 J/eV)(6.67e-11 N*m²/kg²)/(3.00e8 m/s)^4 = 1.18e-48 m. If it passes straight through the earth it sweeps out a cylinder of volume π(1.18e-48 m)²(1.28e7 m) = 5.60e-89 m³. In that volume there are about (5.60e-89 m³)(5500 kg/m³)(6.02e26/kg) = 1.85e-58 protons, so it probably won't hit anything.
Since its velocity is way beyond escape velocity these black holes may present some danger but will not be in the earth's vicinity for long. Any black holes generated by CERN have much more potential for danger if their relative velocities are such that they are captured by the earth's gravitational field. They could then make many more passes through the earth and start to accrete mass.
Just to give you something to think about...
09 Sep 2008, 21:19
Tomasz Grysztar
Assembly Artist

Joined: 16 Jun 2003
Posts: 7724
Location: Kraków, Poland
Tomasz Grysztar
Why the cosmic ray induced black hole must have a velocity "way beyond escape velocity" in your reasoning?
09 Sep 2008, 21:38
revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 17278
revolution
Xorpd!: Remember to take into account relativistic effects.

It seems even a MBH generated in LHC will also have >escape velocity because of the way the relativistic portions distorts the "normal" computation.

Although this stuff is way above my head, I'm just simply paraphrasing from what I have seen written elsewhere by real physicists.
09 Sep 2008, 22:27
Xorpd!

Joined: 21 Dec 2006
Posts: 161
Xorpd!
Well, E = 1e20 eV, Mc² = 4.47e14 eV, so γ = E/(Mc²) = 2.24e5 = 1/√(1-v²/c²).
I get v = (1-2.00e-11)*c. Escape velocity is √(2gR) = √(2(9.81m/s)(6.4e6 m)) = 1.12e4 m/s = 3.74e-5*c.
More telling is that escape kinetic energy is ½mv² = 6.98e-10*mc² but the actual black hole, if formed, has kinetic energy (γ-1)*mc² = 2.24e5*mc², about 3.2e14 times escape kinetic energy.
09 Sep 2008, 22:39
Xorpd!

Joined: 21 Dec 2006
Posts: 161
Xorpd!
Oh, revolution's post appeared while I was preparing my last reply.
My calculations are 100% relativistic, starting with the energy-momentum 4-vector: (mc²)² = E²-(pc)².
09 Sep 2008, 22:45
Tomasz Grysztar
Assembly Artist

Joined: 16 Jun 2003
Posts: 7724
Location: Kraków, Poland
Tomasz Grysztar
This is under silent assumption that the produced black hole equals the total system, isn't it?
Anyway, as probably it might be a justified assumption, there's something more: it's worth considering, that if these were two protons colliding, then the result would have charge, and this would also affect how it is interacting and travelling. I doubt it would be able to escape Earth in such case.

BTW, that reminds me some silly question: why the particles themselves are not a black holes? We consider them to be points, thus infinite density, don't we? Well, there are some nice discussions about it.
09 Sep 2008, 22:54
f0dder

Joined: 19 Feb 2004
Posts: 3170
Location: Denmark
f0dder
I wonder if anybody besides me remember this old game?

 Description: Filesize: 45.29 KB Viewed: 4343 Time(s)

_________________
- carpe noctem
09 Sep 2008, 23:09
Tomasz Grysztar
Assembly Artist

Joined: 16 Jun 2003
Posts: 7724
Location: Kraków, Poland
Tomasz Grysztar
Of course, that's one of my favourites of all the time. I still remember some of the codes. KRFK or HRTB, for example.
09 Sep 2008, 23:10
f0dder

Joined: 19 Feb 2004
Posts: 3170
Location: Denmark
f0dder
It was a game full of joy and frustration - I especially like how you're thrown in medias res without much introduction, and have to figure out stuff by yourself. Suits the game very well. It also had some pretty nice stuff going on technically, like virtual machine stuff, smooth vector animation, etc. And of course the storyline that is soooorta related to this thread's topic

PS: sorry for the offtopic
09 Sep 2008, 23:14
Tomasz Grysztar
Assembly Artist

Joined: 16 Jun 2003
Posts: 7724
Location: Kraków, Poland
Tomasz Grysztar
It's the Heap, I think little offtopic here and there in this section doesn't do much harm.

Do you remember the guy that you had to kill with this green chandelier falling from above? At first I didn't know I could do it this way, but I still managed to kill him - he had quite simple AI and with creating force fields in right places and doing some dodging I was able to finally beat him. I was shocked when then friend showed to me how was I supposed to do it, and that it really hadn't to be SO hard as I made it to myself.

Oh, and I loved the outro and its music.
09 Sep 2008, 23:19
sleepsleep

Joined: 05 Oct 2006
Posts: 8900
Location: ˛　　　　　　　　　　　　　　　　　　　　　　　　　　　　　⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣Posts: 334455
sleepsleep
the webcast couldn't even be viewed. damn
well, now already 3 minutes after the first circulating beam... i am still here. ~ alive

bbc live radio 4 might be usefull
10 Sep 2008, 07:45
Loser

Joined: 12 Jun 2008
Posts: 111
Location: Gliese 581 d
Loser
"Due to a huge interest for this live video feed of the LHC First Beam day, you may not be able to see the live video stream and we apologise for this."

I'm still alive!

EDIT: Oh no! Where is the second part of my message? It is missing! Maybe it was sucked into a tiny black hole created by LHC ...
10 Sep 2008, 08:05
bitRAKE

Joined: 21 Jul 2003
Posts: 2915
Location: [RSP+8*5]
bitRAKE

_________________
10 Sep 2008, 15:37
f0dder

Joined: 19 Feb 2004
Posts: 3170
Location: Denmark
f0dder
Cute pic - one large hadron collider ring to rule them all and in the dark hole bind them?
10 Sep 2008, 23:09
Tomasz Grysztar
Assembly Artist

Joined: 16 Jun 2003
Posts: 7724
Location: Kraków, Poland
Tomasz Grysztar
11 Sep 2008, 09:08
revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 17278
revolution
Tomasz Grysztar wrote:

Nice, I like websites like that. Simple and to the point.
11 Sep 2008, 09:44
vid
Verbosity in development

Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia
vid
Did you know there is remake of Another World by ?Eric Chahi? himself? It has more detailed graphics, double save points ( ), runs on windows, and sells for couple of dollars.

He also posted original videos that he used for in-game cut-scenes to youtube, check it out!
11 Sep 2008, 20:50
edfed

Joined: 20 Feb 2006
Posts: 4237
Location: 2018
edfed
how can i make a site like that?

amithemostcutehuman.com

NO!
11 Sep 2008, 20:53
f0dder

Joined: 19 Feb 2004
Posts: 3170
Location: Denmark
f0dder
vid: yeah, there's a "deluxe" version or whatever

It also has a "behind the scenes video", but the idiots made it in french and it only has german subs, iirc. ENGLISH, PLEASE! Grr.
11 Sep 2008, 20:54
vid
Verbosity in development

Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia
vid
edfed wrote:
how can i make a site like that?

Look for "domain registrators" in your country. Usually offered by webhosting companies too.

11 Sep 2008, 22:51
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