Large Hardon Collider

[Altariel]

I wish I wasn't such an idiot about geometry. But if I follow what Max is saying spherical objects appear as lenses from the surface of "our sphere" or as circles when intersecting a flat surface? Essentailly when Penrose's spheres hit the WMAP sensors they looked like circles akin to why photos of the moon appear as discs. But where I get lost is that this information is the information is arbitrarily displayed as Mollweide projection so shapes become increasingly distorted the farther from it's equator and prime meridian you look. So a circle in the center of the WMAP image I would expect to appear circular but anything that was anywhere else should not be, right?

[Max™]

We're looking at the interior surface of a sphere, for all intents and purposes, when we observe the CMBR.

Spoiler: show

http://universe-review.ca/I02-31-CMBR.jpg
The intersection of gravitational ripples from the far side of the CMBR and the side we can see would produce circular artifacts like in the diagram below.

http://www.etsu.edu/physics/etsuobs/...bg/spheres.gif
The projection we usually see:
http://ya.astroleague.org/wp-content..._microwave.jpg
...is just a way to cut open the inner surface of a sphere and lay it out flat, otherwise you'd have to stick your head inside the image.

http://www.imagecows.com/uploads/012...projection.jpg

A Mollweide Projection is usually the exterior surface of a sphere, so you can think of that one as being cut open on the far side from your position and unfolded towards you from there.

The CMBR is cut open behind you, and unfolded from around you so it lays flat. It's probably worse if you already know what a Mollweide is, since you're probably trying to picture folding the CMBR map away from you to fit around a sphere, huh?

http://imagine.gsfc.nasa.gov/Images/...map/091057.jpg

[Kaylia]

How do you find the value of a gaussian integral between 2 random value (not 0 and infinity)? I've done it numerically many time, just curious how you would proceed otherwise.

[Eliseos]

Integrate by parts, and use a few u substitutions. Woozie did it in this thread earlier this year after I asked about it, probably somewhere in September/October. It has the steps there.

[Woozie]

The one I did was from 0 to infinity (or negative infinity to infinity. I don't remember which).

For some number to some other number, numerically is the only way to do it. e^(-ax^2) has no antiderivative (well, unless you do a Taylor series or something).

[Kaylia]

Yeah, that's pretty much why I was clueless how to do it. I just hate tossing numerical results when I'm writting a paper...it make me feel dirty.

[Kaylia]

...just tossing it here since I''m stuck on this bit since 3hours. Anyone see a way to simplify (exp(-x)+ exp(x)+1)^N more than (2cosh(x)+1)^N. I feel like I'm forgetting somtehing but half angle or circle formula isn't working here.

[edit]
Turn out it become a tanh later in the problem, so nvm that.

[Ferion]

This is probably a really dumb question if you actually know anything about physics but I figured this would be the place to bring it up since it involves radiation. The other day my family got into a debate about whether long term exposure to laptops can be a health risk. Since I spend a ton of time on my computer I decided to do my own research. Basically what I found were some pretty biased seeming websites that said "yes it is a health risk, laptops give off low levels of radiation." I also found some unbiased seeming websites that basically said "there's no evidence linking radiation from laptops to any kind health risks." I however did not find anyone that said there is evidence that shows there are no health risks from using a laptop, just that there is no evidence showing there is a health risk. So I was just kind of curious what your guys' opinions are on the subject and if there is a more scientific explanation behind this than what I've found. It's amazing the things that you come up with to procrastinate when you're stuck working on a research paper over winter break.

[BerenTebogo]

Every energy source gives off radiation so the whole argument is kind of a misnomer (which is why you find such divergent mindsets). You can make the case that yes, laptops give off a lot of "radiation". Is it harmful radiation? As far as I know all experimental studies show that, no, it isn't. It's one of those things that you can figure out if you think about it a bit. How would a laptop give off dangerous radiation? The screen? Everyone in the first world is going to get screen-cancer from their HDTVs, cell phones, computers, etc. You can use your own logic to see that is just silly. Lithium-ion batteries? Well, why is it any more dangerous than a normal battery-powered device? Comes back around to pretty much anyone using an Energizer battery or laptop, or cell phone, or ipod is going to die of Lithium cancer. Etc, etc, etc.

People are silly, and easily scared. I'm no expert on radioactivity but the term is so inappropriately used these days that of course there is a lot of crazy shouting. Electrical devices do give off radiation. Will you get sick from it? I highly, highly, highly doubt it.

Posting from my laptop as it rests, steamily hot, on my balls.

[Tyche]

http://www.blackcatsystems.com/GM/pr...erCounter.html

It's got a USB port, plug it into the laptop and check the readings.

Spoiler: show

Someone is going to take that seriously...

[Ferion]

Thanks Sath, that was pretty much my thought process, just wanted to see if some one had some kind of deep explanation that countered that kind of argument. The more I follow this thread the more I keep telling myself that I need to start looking over some physics in my free time. I actually got "Death By Black Hole" for Christmas and I'm really enjoying it so far, so we'll see what happens when I finish it.

[Max™]

Typical daily doses of radiation:
http://www.askaboutireland.ie/_inter...kxxaj93gllesrv

LOOK OUT FOR RADON, DUDE!

http://www.epa.gov/rpdweb00/understand/calculate.html

[Kaylia]

@Ferion
"Radiation" on its own mean very little. What you need to know is how energetic the radiation is and the impact on the matter (Does it ionize atoms? Destroy molecules?..etc).

What people consider radioactive usually refer to highly energetic particles (alpha, beta, gamma, etc) that can easily destroy a molecule. These radiations might be present everywhere in the nature, but they are still considered harmful. You don't want to get exposed more than you currently are, because it does increase the risk of getting cancer considerably.

In laptops case (and cellphones), we are talking about normal electromagnetics radiation (visible light, electricity, heats all fall in that category). While it sound harmless when I put it this way, you can't easily dismiss the claim. Many chemicals process in your brain are ionized (synapse for example), and some complex process like DNA creation can be influenced by electromagnetics field. While evolution made us resistant to such energy level, it's still much more EM than what you find in the nature, and it might be enough to cause a non trivial odd of cancer.

I just google'd it, there might be something better, but it show clearly that electromagnetics wave do have some impact on biology.
http://www.sciencedaily.com/releases...0219075606.htm


Anyway, everyone is going to die sooner or later. Try living a healthy life if you want to see your grandchilds (eat well, exercice, sleep properly), that's what matter the most. It's not possible to optimize every single "risk", and running away from everything is kinda stupid. In this case, the risk is not zero, but it's not very high either in the worst case. That's why I think it's stupid to worry about it when there is most likely something much worse that you're doing.

Is it harmful radiation? As far as I know all experimental studies show that, no, it isn't. It's one of those things that you can figure out if you think about it a bit. How would a laptop give off dangerous radiation? The screen? Everyone in the first world is going to get screen-cancer from their HDTVs, cell phones, computers, etc. You can use your own logic to see that is just silly.

Radiations decrease with r³. People are worried about laptop and cellphones simply because the field that goes through your nads and brain is much stronger than the one emited by a distant object like a TV (or pretty much anything you deal with everyday). It's the same deal for house located under high tension line or people who sleep next to a power socket.

It's not like you won't wake up tomorrow, but the risk of developping cancer because of this is not zero. Is it 0.0001%, 0.05% or 1%? I doubt anyone can tell, and while I agree it's not something we should really worry about, I don't think any experimental studies show that it has no impact.


[edit]
And I agree people are scared about the word "radiation" more than the real physics behind it. It's kinda stupid.

[Shuvo]

Ok sooo.. i haven't read this thread at all since page 1 when it first started... has their been any important discoveries yet? >_>

[Kaylia]

has their been any important discoveries yet? >_>

Yes, many. Physics/maths homeworks blow, webcomics are hilarious, psi does not exists, physicist are unable to get decent job (because engineers steal everything), etc.

[Shuvo]

physicist are unable to get decent job (because engineers steal everything)

Sorry :X

At least the physicists have plenty of time to play starcraft ;D

[Kaylia]

But seriously, not much has been released yet. This is not to say there is no interesting result for sciences, but there isn't anything interesting for someone not well versed in the domain (pretty much everyone here). What it did so far is reconfirm what we already knew (not a bad thing), but that's motly it. I think it confirmed some weird particles entanglement as well, but I'm not sure.


Personally, the most interesting discovery of the year goes to penrose's circle
http://www.universetoday.com/79750/p...fore-big-bang/


[edit]
The circle are real (I hope), but the theory/conclusion is very debatable.

[Eliseos]

We don't steal jobs, we just know how to make things cool. There are a few SMBC comics that prove this.

[Woozie]

http://www.physorg.com/news189694649.html

Einstein equations indicate possibility of black hole formation at the LHC

Spoiler: show

(PhysOrg.com) -- One of the concerns that has been voiced about the Large Hadron Collider (LHC), is that it could result in the formation of black holes that could destroy the world. While most scientists dismiss claims that anything produced in the LHC would destroy the planet, there are some that think that black formation could be seen with LHC collisions of sufficiently high energy. This idea has gotten a further boost from recent efforts by Matthew Choptuik at the University of British Columbia in Vancouver, and Frans Pretorius, at Princeton University in New Jersey.

“What we did was a calculation,” Choptuik tells PhysOrg.com. “We solved some of the Einstein field equations describing head on soliton collisions at certain energies.” Choptuik and Pretorius present their work, and their conclusions, in Physical Review Letters: “Ultrarelativistic Particle Collisions.”

“Our calculation produced results that most were expecting, but no one had done the calculation before. People were just sort of assuming that it would work out,” Choptuik says. “Now that these simulations have been done, some scientists will have a better idea of what to look for in terms of trying to see if black holes are formed in LHC collisions.”

Choptuik points out that there has been an effort for more than 50 years to marry particle physics with the idea of gravity. “At the level of classical physics we think we understand gravity pretty well,” he explains. “However, at the quantum mechanical level, gravity is not at all well understood. Scientists have been looking for a way to understand quantum gravity in the same way as we understand how the smallest particles work on a quantum level. While solving these equations doesn’t answer all the questions, it does substantiate what we have already assumed.”

One of the keys to the principles behind these field calculations is string theory. String theory suggests that there are several dimensions beyond the three spatial dimensions (plus time) that we see in classical physics. “If extra dimensions do exist, they could be as large as 10s to 100s of a micrometer. And if those extra dimensions are big enough, then there is a chance that the particle collisions at the LHC might be able to form black holes,” Choptuik says.

Of course, these black holes would be quite tiny, and difficult to detect. On top of that, they would evaporate almost instantly, making it even more difficult to detect whether they had even existed. “In collision like this, you would have to look at the debris,” Choptuik explains. “You’d look at the decay pattern in space. In a normal collision, you would get jets of debris. If a black hole was created and evaporated, the pattern would look more spherical than jet-like.”

However, the fact that the solution of these Einstein field equations suggests that black hole formation could be possible at the LHC is a far cry from actually detecting it. “Some are already taking this very seriously,” Choptuik says. “However, I don’t think that we are likely to actually see any black holes at the LHC, even if it is possible.”

WE"RE ALL GONNA DIEEEEEEEEEEEEEEEEE!!!!!!!!

But in all seriousness:

One of the keys to the principles behind these field calculations is string theory.

So yeah....this article is basically science-fiction. I just thought I'd bring this up and point out the obvious flaw before someone who isn't into physics sees this somewhere else online (since they may not realize that using string theory is a huge flaw).

[Mizango]

http://www.physorg.com/news189694649.html

Einstein equations indicate possibility of black hole formation at the LHC

Spoiler: show

(PhysOrg.com) -- One of the concerns that has been voiced about the Large Hadron Collider (LHC), is that it could result in the formation of black holes that could destroy the world. While most scientists dismiss claims that anything produced in the LHC would destroy the planet, there are some that think that black formation could be seen with LHC collisions of sufficiently high energy. This idea has gotten a further boost from recent efforts by Matthew Choptuik at the University of British Columbia in Vancouver, and Frans Pretorius, at Princeton University in New Jersey.

“What we did was a calculation,” Choptuik tells PhysOrg.com. “We solved some of the Einstein field equations describing head on soliton collisions at certain energies.” Choptuik and Pretorius present their work, and their conclusions, in Physical Review Letters: “Ultrarelativistic Particle Collisions.”

“Our calculation produced results that most were expecting, but no one had done the calculation before. People were just sort of assuming that it would work out,” Choptuik says. “Now that these simulations have been done, some scientists will have a better idea of what to look for in terms of trying to see if black holes are formed in LHC collisions.”

Choptuik points out that there has been an effort for more than 50 years to marry particle physics with the idea of gravity. “At the level of classical physics we think we understand gravity pretty well,” he explains. “However, at the quantum mechanical level, gravity is not at all well understood. Scientists have been looking for a way to understand quantum gravity in the same way as we understand how the smallest particles work on a quantum level. While solving these equations doesn’t answer all the questions, it does substantiate what we have already assumed.”

One of the keys to the principles behind these field calculations is string theory. String theory suggests that there are several dimensions beyond the three spatial dimensions (plus time) that we see in classical physics. “If extra dimensions do exist, they could be as large as 10s to 100s of a micrometer. And if those extra dimensions are big enough, then there is a chance that the particle collisions at the LHC might be able to form black holes,” Choptuik says.

Of course, these black holes would be quite tiny, and difficult to detect. On top of that, they would evaporate almost instantly, making it even more difficult to detect whether they had even existed. “In collision like this, you would have to look at the debris,” Choptuik explains. “You’d look at the decay pattern in space. In a normal collision, you would get jets of debris. If a black hole was created and evaporated, the pattern would look more spherical than jet-like.”

However, the fact that the solution of these Einstein field equations suggests that black hole formation could be possible at the LHC is a far cry from actually detecting it. “Some are already taking this very seriously,” Choptuik says. “However, I don’t think that we are likely to actually see any black holes at the LHC, even if it is possible.”

WE"RE ALL GONNA DIEEEEEEEEEEEEEEEEE!!!!!!!!

But in all seriousness:



So yeah....this article is basically science-fiction.

As soon as I saw that "string theory" part I calmed down.