Large Hardon Collider

[Eliseos]

You guys assume the worst about bacteria. What if they just want to be our friends?

[Max™]

Awww, but he's so cute and cuddly!
http://www.thinkgeek.com/images/prod...eria-ecoli.jpg

@Tristam, I was posting something about CO2 but it got lost, it was about the "we know it is a forcing factor now" thing, I was under the impression that historical CO2 rises have lagged by a not-insignificant period of time behind temperature rises, was that disproved?

[Mizango]

What's funny about that Max is I used to have a plush pillows of a planarian and a euglena when I was like 12 or so lol. Looking back at pictures maaaaan, the planaria one looks like I was cuddling next to a giant penis It was one of my favorite pillows too, man that wasnt good.

[Effluo]

Parrarel Universe go!
http://abcnews.go.com/Technology/wireStory?id=11926151

GENEVA (Reuters) - Physicists probing the origins of the cosmos hope that next year they will turn up the first proofs of the existence of concepts long dear to science-fiction writers such as hidden worlds and extra dimensions.

And as their Large Hadron Collider (LHC) at CERN near Geneva moves into high gear, they are talking increasingly of the "New Physics" on the horizon that could totally change current views of the universe and how it works.

"Parallel universes, unknown forms of matter, extra dimensions... These are not the stuff of cheap science fiction but very concrete physics theories that scientists are trying to confirm with the LHC and other experiments."

This was how the "ideas" men and women in the international research center's Theory Group, which mulls over what could be out there beyond the reach of any telescope, put it in CERN's staff-targeted Bulletin this month.

As particles are collided in the vast underground LHC complex at increasingly high energies, what the Bulletin article referred to informally as the "universe's extra bits" -- if they do exist as predicted -- should be brought into computerized, if ephemeral, view, the theorists say.

Optimism among the hundreds of scientists working at CERN -- in the foothills of the Jura mountains along the border of France and Switzerland -- has grown as the initially troubled $10 billion experiment hit its targets this year.

PROTON COLLISIONS

By mid-October, Director-General Rolf Heuer told staff last weekend, protons were being collided along the 27-km (16.8 mile) subterranean ring at the rate of 5 million a second -- two weeks earlier than the target date for that total.

By next year, collisions will be occurring -- if all continues to go well -- at a rate producing what physicists call one "inverse femtobarn," best described as a colossal amount, of information for analysts to ponder.

The head-on collisions, at all but the speed of light, recreate what happened a tiny fraction of a second after the primeval "Big Bang" 13.7 billion years ago which brought the known universe and everything in it into being.

Despite centuries of increasingly sophisticated observation from planet Earth, only 4 per cent of that universe is known -- because the rest is made up of what have been called, because they are invisible, dark matter and dark energy

Billions of particles flying off from each LHC collision are tracked at four CERN detectors -- and then in collaborating laboratories around the globe -- to establish when and how they come together and what shapes they take.

The CERN theoreticians say this could give clear signs of dimensions beyond length, breadth, depth and time because at such high energy particles could be tracked disappearing -- presumably into them -- and then back into the classical four.

Parallel universes could also be hidden within these dimensions, the thinking goes, but only in a so-called gravitational variety in which light cannot be propagated -- a fact which would make it nearly impossible to explore them.

(Editing by Jonathan Lynn)

[Tristam]

@Tristam, I was posting something about CO2 but it got lost, it was about the "we know it is a forcing factor now" thing, I was under the impression that historical CO2 rises have lagged by a not-insignificant period of time behind temperature rises, was that disproved?

If it's an amplifying feedback, you would expect it to lag. Orbital forcing, prior to the industrial revolution, was the thing that set everything in motion, and it took time to build up energy, because it's really a very subtle change in the energy budget. I forget whether ice sheets respond before CO2, but you can imagine that changing ice sheet area changes arable land for plants changing atmospheric CO2 and so on. But those things take time, lots of time. There may have been CO2 forcings as well, but I can't think of anything in the carbon cycle that would cyclically overlap with milankovitch cycles.

[Mizango]

Posted on my FB page but Ill post this here for anyone interested. This is a really neat conversation Richard Dawkins and Neil deGrasse Tyson in DC 3 weeks ago. Watched it in its entirety but man this is a fantastic video and very interesting. Everything from evolution, math, human genome to simple concepts of Astrophysics. If you have time definitely check it out, its phenomenal.

Woozie if it makes you feel better Dr Tyson asked me to share it with my friends and give him feedback Told him I had just the people in you, Eli and Sath. Hope that makes up for you not being able to add him @@

http://www.youtube.com/watch?v=9RExQFZzHXQ

[BerenTebogo]

Doing practice test for my second Calc 2 exam tomorrow without an answer key and wolfram doesn't like this problem. Can anyone confirm or deny if:

the integral of x * e^(2x) dx from negative infinity to 0 = -1/4 ?

I'd show my math but it's aggravating enough trying to just type out the problem and having it make sense, lol.

[Woozie]

That's correct.

[BerenTebogo]

Sweet! Thanks a bunch.

[BerenTebogo]

One more problem, and I'm not sure if it's an error on my part, a small error my prof. made (he made up a few q's at the end of class for us to write down and practice) or if I just made an error copying the problem down, but

"Prove that An = n/ (n^2 + 3) decreases and is bounded." I'm solving using the derivative check method and I basically get that it it's increasing between 0 and sqrt(3/2) and then decreases from sqrt(3/2) to lim n->0. Now for a sequence that supposedly begins at 1, this technically both increases and decreases...so I dunno.

Any clarification would be awesome :\

[Woozie]

You're not doing anything wrong (well, except you should have gotten sqrt(3), unless I'm the one doing something wrong). A_n actually increases from A_1 to A_2, so unless your professor told you to start the function from 2 or above, he's asking you to prove a false theorem. You can easily check by hand that A1=.25 and A2 = .285714...

Of course, typically you only care about the end behavior of a sequence anyways. And to show that it's bound, you can easily see that A_n is always positive and thus is bounded below by zero. Since it's decreasing on 2->infinity, the part of the sequence from 2 and above is bounded by A_2. So either A_2 or one of the terms before A_2 (i.e. A_1) has to be an upper bound. In this case, A_2>A_1, so A_2 is an upper bound.

Edit: You meant it decreases from (sqrt(3),infinity), right?

[Max™]

Speaking of not being sure about your math!
http://imgs.xkcd.com/comics/los_alamos.png

Btw, Tristam, I think I was replying to you a while back but the power blinked on me. If CO2 increases caused the temperature to rise, but temperature increases precede CO2 increases by years to decades historically, wouldn't that mean CO2 particles travel at roughly 88 mph in the atmosphere?


For the record, it's S:OH C:AH T:OA, right?

[Eliseos]

Doing practice test for my second Calc 2 exam tomorrow without an answer key and wolfram doesn't like this problem. Can anyone confirm or deny if:

the integral of x * e^(2x) dx from negative infinity to 0 = -1/4 ?

I'd show my math but it's aggravating enough trying to just type out the problem and having it make sense, lol.

I always check my definite integrals with http://www.wolframalpha.com/

Typing in "the integral of x * e^(2x) dx from negative infinity to 0" gives http://www.wolframalpha.com/input/?i=the+integral+of+x+*+e^%282x%29+dx+from+negative +infinity+to+0

If you don't type in the limits of integration, it'll show the steps on arriving to the indefinite integral.

Edit: Oh well I'm an idiot and didn't see the word wolfram in your post.

[Altariel]

Thanks for posting the Richard Dawkins and Neil deGrasse Tyson video. I could have listened to them chat for hours. "Life is just the extreme expression of complex chemistry." Awesome line!

I do wish that the "horizon question" would have been addressed more fully. Neil deGrasse Tyson uses the analogy of the horizon of a ship on earth but I always have a problem getting my head around this type of comparison. The earth is (more or less) a sphere; you could travel forever in any direction and never run into the "end". But we don't really know much for certain about the shape and topology of the universe. If everything inflated from a specific point, why can we not presume that some observer's horizons sit along the "leading edge" of the inflation and there is just simple not 14 billion light years of "stuff" in a particular direction. For the vast majority of observers inside the "bubble" of our universe I totally get the analogy, but I'm not sure that is what Dawkins was getting at.

I would have liked Dawkins to elaborate a bit more about the complexities of turning inactive genes in our DNA on. As he explains in many of his works we often get lured into the idea of there being genes "for" things. Unless you are talking about very specific traits like "the ability to taste PTC" there is often a complex of many genes which interact together which express themselves in a specific way. He glosses over this a bit saying that turning on a dog's sense of smell would be complicated. But there really isn't probably a gene "for dog smelling ability" but rather a number of genes that when activated together express themselves as increased smelling ability.

[geno]

Glad I stumbled into this thread to notice that video, if only to hear Neil briefly mention at the end of the booksigning something about a full science lineup on wednesday nights starting with Nova Science Now come January. I loved that show and was wondering why it never popped up on my DVR anymore

Of course the video itself was awesome, I've seen so many talks with both figures on youtube over the years and they never get old (though I have to admit I'm more partial to Tyson's topics of expertise overall, as well as his general pop-sci approach to speaking).

[Kaylia]

Spoiler: show

I asked for a demonstration of lagrange multiplier last months and got a nice answer...but here I am again, with a question about the same thing.

http://xbeams.chem.yale.edu/~batista...grangeMult.pdf

On page 4, the first 3 lines...I simply can't understand the reasoning. I understand the inequality, but I cant figure out how they draw that conclusion from it.

Never mind, figured it out.



[edit]
Anyone know how i can numerate my equation in word. I'm using the equation editor to write my stuff, but cant figure out how to add a number next to them (3.1, 3.2...etc)

[Ferion]

You're not doing anything wrong (well, except you should have gotten sqrt(3), unless I'm the one doing something wrong). A_n actually increases from A_1 to A_2, so unless your professor told you to start the function from 2 or above, he's asking you to prove a false theorem. You can easily check by hand that A1=.25 and A2 = .285714...

Yeah, but just because it's not a monotone decreasing sequence does not mean it's not decreasing. Although I guess this sequence is monotonic and decreasing after it reaches A2 and strictly increasing from A1 to A2. The professor probably just wanted to see if the class had a premature understanding of of a least upper bound and greatest lower bound, unless that's something you learned already which I didn't until my first analysis course. I'm not sure what your professor would be looking for exactly, but you could just find the limit of the sequence is 0 which means that it's decreasing since the sequence is always positive. Then state that since the sequence has a limit, it must be bounded from above and below.

Edit: For some reason I didn't read the rest of Woozie's post past the first couple of lines until after I wrote this. He explained the reasoning a lot better than I probably did.

[BerenTebogo]

I'm pretty sure my prof. just wrote the problem wrong since when he referenced it today it was more logical. I'd explain better but I just got out of my exam and I'm exhausted, lol.

The limits of sequences make ZERO logical sense unless I just don't understand them enough yet. We've only done the very first section of intro to sequences so I know there's MUCH more to learn but one of the problems on my test was like discuss the properties of the sequence n+1/2n-3 and find the limit. I did all the math correctly (checked a few min ago on wolfram since I remembered the problem) but when I graphed the function and looked at the values in a table it didn't make sense to me. I keep seeing the discontinuity of the function at 3/2, the table gives error at 3/2, the derivative of the sequence when turned into a function approaches 0 from like -5 or something? and the limit is 1/2.

I'm just honestly confused with the concept I guess. The derivative test is like it was in calc 1 I assume? Just to test increasing or decreasing (or concavity?), but how is the function increasing when the sequence appears to be decreasing towards 1/2?

I'm doubting I'll get full credit on the problem since I feel like I did something wrong, but looking again at the derivative of the function the lowest boundary (for all x > 1) is -5 and it approaches 0. So, I don't know. I'm splitting hairs over what will probably be ~5 points of the total test, but I'm kinda raging over it too.

tl;dr: so far, fuck sequences. I need to learn more about them.

[Kaelan?]

I do wish that the "horizon question" would have been addressed more fully. Neil deGrasse Tyson uses the analogy of the horizon of a ship on earth but I always have a problem getting my head around this type of comparison. The earth is (more or less) a sphere; you could travel forever in any direction and never run into the "end". But we don't really know much for certain about the shape and topology of the universe. If everything inflated from a specific point, why can we not presume that some observer's horizons sit along the "leading edge" of the inflation and there is just simple not 14 billion light years of "stuff" in a particular direction. For the vast majority of observers inside the "bubble" of our universe I totally get the analogy, but I'm not sure that is what Dawkins was getting at.

Wasn't it shown that the universe was "flat" (as opposed to open or closed) some time ago? Or has that changed? It's one of the few things I remember from last time I watched Lawrence Krauss's lecture on the Universe.

[Max™]

I think it was shown that the observable universe only has enough matter to be within a tiny deviation from flatness either way, but it could still have a weird geometry on larger scales. Like, atari asteroids weird.

*goes -> that way for billions of light years*

*<- winds up over there*


Sath, why wouldn't there be a discontinuity/error where n=1.5? I'd figure at (2.5)/(3-3), the computer says "ha ha, fuck you" then shits on your desk.