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Comment: Re:Student loans led to the education bubble (Score 2) 834

by niklask (#39940439) Attached to: GOP Blocks Senate Debate On Dem Student Loan Bill

You can get better education, free or nearly free, in most of Europe, and yet the US youth just sits there, saddling itself with gazillions in student loan debt -- all of which it cannot default on, because it belongs to uncle Sam himself. Shudder...

One can argue which universities in the world are the best, which metric to use etc, but higher education is not free in Europe. It is payed for with tax euros, or as in my case, tax kronor, as I got my education in Sweden. What you fail to understand is that students in Europe, in Sweden at least, take students loan too. There may not be tuition fees but students have to pay rent, eat, pay for books etc too you know. So while the total student loan amount in Sweden is generally smaller than in the U.S., students still have big loans in relation to expected future salaries. Very few are fortunate enough to go through higher education without student loans in Sweden.

Comment: Re:What's the problem in building the future. (Score 1) 318

by niklask (#39443551) Attached to: Ask MIT Researchers About Fusion Power

Uranium has a large cross-section, yes, but do you think it is likely that they will build the reactor cladding from U-235?

That I made no comment on, I just happened to have the neutron cross sections in different Uranium isotopes at hand and used that as an example of how much the cross section can vary depending on the target material.

Comment: Re:What's the problem in building the future. (Score 1) 318

by niklask (#39443271) Attached to: Ask MIT Researchers About Fusion Power
That is no entirely correct either. If the cross section was tiny then it would not transmute nuclei. The neutron cross section is dependent on both energy and the material. The interaction cross section of a 1 MeV neutron is about 1 barn in 235-U but only 0.01 barn in 238-U. And 1 barn is not tiny.

Comment: Re:What's the problem in building the future. (Score 1) 318

by niklask (#39442027) Attached to: Ask MIT Researchers About Fusion Power

Fusion reactors generate enormous amounts of neutrons, which interact only weakly with matter.

This is completely wrong. Neutrons are strongly interacting particles. If they weren't they would not stay bound in atomic nuclei. A statement like that implies that a particle only interacts via the weak interaction, which is not correct for nuetrons./p

Comment: Re:Universe is too Strange! (Score 1) 164

by niklask (#38464672) Attached to: New Particle Identified At LHC

If CERN was doing real science (at the LHC) they would have been able to say with confidence that they were going to find (or not find) this "new" "particle" months ago and give reasons for exactly where and how they expected to find it.

What part of the fact that the Standard Model predicts this bound state at this mass did you not understand?

Comment: Re:Systematic Error (Score 1) 115

by niklask (#34188926) Attached to: Massive Gamma Ray Bubbles Discovered In Milky Way

You do realize that even CfA people aren't experts in all fields, right? Doing Fermi-LAT is very tricky in the Galactic plane and only maybe a handful of people in the LAT team know how to do it correctly. That being said, this result isn't necessarily wrong but it needs to be taken with a grain of salt.

Comment: Re:Doppler effect? I don't know... (Score 1) 214

by niklask (#31775360) Attached to: Yoctonewton Detector Smashes Force Sensing Record

From the article itself:

Their kit consists of a few dozen beryllium ions trapped in magnetic and electric fields using a device called a Penning trap. These ions vibrate at between a few mega and kilohertz, frequencies that can be accurately measured by bouncing laser light off the ions and measuring any Doppler shift they cause.

Me thinks you forgot to read the part about bouncing photons off the ions. The ions will be moving relative to the photons due to the vibrations.

Comment: Re:Implications for dark matter estimates? (Score 1) 279

by niklask (#31621422) Attached to: 90% of the Universe Found Hiding In Plain View

No, the neutralino does not interact through the weak interaction.

They really do. To quote the Berkeley CDMS website linked from the Ars article about possible (but very speculative) dark matter detection, who are trying to detect WIMPS and in specific neutralinos:

Specifically, a cross section for interaction between a neutralino and a nucleon in ordinary matter of the order of the electro-weak scale would be consistent with a meaningful cosmological role for the particle. This expectation of a weak interaction together with the expected mass range of the neutralino, 10 to 1000 GeV, produce the acronym "WIMP": Weakly Interacting Massive Particle.

So that and other usages of "weak interaction" lead me to believe neutralinos interact via the weak interaction.

I would expect there to be differences in the experiment, but the overview seems very similar: Put an extremely sensitive detector as far down in the earth as you can to shield yourself from as many normal cosmic rays and particles as possible, and wait for years to see enough events to say you've got a decent probability of having actually seen something real.

Weakly interacting does not mean that it interacts via the weak interaction. That is why direct detection experiments look for elastic interactions between a dark matter particle and a nucleus in the experiment. This is why you have to minimize the background as much as possible.

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