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Author Topic: SCIENCE, Gravitational waves, and the whole LIGO OST!  (Read 310586 times)

Another

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Re: SCIENCE, the Higgs, and everything else!
« Reply #645 on: July 18, 2013, 12:31:32 pm »

In physics if a preprint is not at http://arxiv.org - it is very likely that the article in question is not novel/important at all.

On the other hand - stuff on arXiv that does not mention [upcoming] publication in specific journals tends to be less well thought out.

The worst situation is with papers from before the 90s.
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Scelly9

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Re: SCIENCE, the Higgs, and everything else!
« Reply #646 on: July 18, 2013, 02:26:01 pm »

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MonkeyHead

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Re: SCIENCE, the Higgs, and everything else!
« Reply #647 on: July 18, 2013, 02:49:58 pm »

Anything I ever need can be found on arXiv for free. I cant speak for subjects other then Physics in terms of quality, but there is plenty on there for all other academic sciences more or less.
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Re: SCIENCE, the Higgs, and everything else!
« Reply #648 on: July 18, 2013, 06:33:47 pm »

Paper pay-walls are only a problem if you want to access stuff from home. Most universities offer access to all relevant sources in their networks or libraries. And most stuff that does not exist in electronic form and is not present in the library can be accessed through interlibrary loan.
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DWC

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Re: SCIENCE, the Higgs, and everything else!
« Reply #649 on: July 18, 2013, 09:23:39 pm »

So, this is cool.

That actually is really cool. This means no limit to the power of lasers besides the amount of energy you put into them. Normally, a laser will actually melt itself from some of the energy of it's beam being absorbed by the mirrors that amplify it's energy. With a perfect mirror, this means there is perfect energy output. No limit to how powerful a laser can be.

This could even be a means of energy transmission. Not to mention death-rays that can destroy anything that isn't also another perfect mirror.

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Lagslayer

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Re: SCIENCE, the Higgs, and everything else!
« Reply #650 on: July 18, 2013, 09:53:44 pm »

Every material has a breaking point. Eventually, the kinetic force of the laser will be strong enough to break the mirror.

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Re: SCIENCE, the Higgs, and everything else!
« Reply #651 on: July 18, 2013, 09:58:54 pm »

Every material has a breaking point. Eventually, the kinetic force of the laser will be strong enough to break the mirror.

Bro, lasers have no kinetic energy because the photon has zero/infinity mass. It moves at the speed of light. So... E=MC^2 and if M = 0 then E=0.

So yeah.
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Lagslayer

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Re: SCIENCE, the Higgs, and everything else!
« Reply #652 on: July 18, 2013, 10:02:45 pm »

Even the "light has no mass" people say it has momentum. It is documented and accepted as scientific fact.

http://en.wikipedia.org/wiki/Solar_sail

Scelly9

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Re: SCIENCE, the Higgs, and everything else!
« Reply #653 on: July 18, 2013, 10:10:11 pm »

Fuck, science is cool.
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DWC

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Re: SCIENCE, the Higgs, and everything else!
« Reply #654 on: July 18, 2013, 10:17:26 pm »

Even the "light has no mass" people say it has momentum. It is documented and accepted as scientific fact.

http://en.wikipedia.org/wiki/Solar_sail

Bro, electromagnetic radiation includes light, but isn't all like light. Light is special, it's like a particle and a wave at the same time. The only thing a laser uses is light, it doesn't spew out gammas or radio wave or infrared or anything else besides light. The sun spews out everything in the electromagnetic spectrum, including light because it's basically a roiling cloud of hydrogen bombs going off. A solar sail would work because of everything it is sending out (besides light) is causing radiation pressure on the object. Not to mention like, regular thermal energy produced by the sun.

Also, outer space is not a perfect vacuum. The space inside a laser could be a perfect vacuum, with perfect lens and perfect mirrors could produce a ridiculously powerful laser, really only limited by the amount of energy put into it. How awesome are fucking lasers anyways?
« Last Edit: July 18, 2013, 11:23:13 pm by DWC »
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Loud Whispers

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Re: SCIENCE, the Higgs, and everything else!
« Reply #655 on: July 18, 2013, 11:49:13 pm »

Also, outer space is not a perfect vacuum. The space inside a laser could be a perfect vacuum, with perfect lens and perfect mirrors could produce a ridiculously powerful laser, really only limited by the amount of energy put into it. How awesome are fucking lasers anyways?
How much power?

Sirus

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Re: SCIENCE, the Higgs, and everything else!
« Reply #656 on: July 18, 2013, 11:53:45 pm »

I could be wrong, but I don't think we have perfect lenses yet. And I don't think there's any such thing as a "perfect vacuum", thanks to those pesky neutrinos that love to fly through miles of solid material before colliding with a lucky subatomic particle.
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Re: SCIENCE, the Higgs, and everything else!
« Reply #657 on: July 19, 2013, 12:27:02 am »

Paper pay-walls are only a problem if you want to access stuff from home. Most universities offer access to all relevant sources in their networks or libraries. And most stuff that does not exist in electronic form and is not present in the library can be accessed through interlibrary loan.

It can be an issue for the libraries themselves. Every once in a while you hear about them dropping certain overpriced journal subscriptions. Sometimes it's part of a boycott, sometimes it's purely for budget reasons. A lot of smaller colleges and universities can't justify the cost of journals that charge an arm and a leg while only being marginally useful.

Obviously big research universities need to have access to as many journals as possible for their research community (you'd be surprised how far afield some articles can end up), but those with less research focus can drop a great many of their subscriptions without too much harm.



As for the perfect mirrors, sounds very constrained in wavelength and angle. Still incredibly cool.

However, DWC, no. Light does have momentum as any other electromagnetic wave. And all objects have both wave and particle behaviour. You can create elements of the laser effect (the spatial coherence at least) with any bosonic matter, including (in limited ways) certain atoms. Lasers in a exact sense can and do exist all across the electromagnetic spectrum. Hell, masers (microwave lasers) pre-date optical lasers. I've used X-ray lasers, and IR lasers are incredibly common.
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MonkeyHead

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Re: SCIENCE, the Higgs, and everything else!
« Reply #658 on: July 19, 2013, 01:15:47 am »

Even the "light has no mass" people say it has momentum. It is documented and accepted as scientific fact.

http://en.wikipedia.org/wiki/Solar_sail

Bro, electromagnetic radiation includes light, but isn't all like light. Light is special, it's like a particle and a wave at the same time. The only thing a laser uses is light, it doesn't spew out gammas or radio wave or infrared or anything else besides light. The sun spews out everything in the electromagnetic spectrum, including light because it's basically a roiling cloud of hydrogen bombs going off. A solar sail would work because of everything it is sending out (besides light) is causing radiation pressure on the object. Not to mention like, regular thermal energy produced by the sun.

Also, outer space is not a perfect vacuum. The space inside a laser could be a perfect vacuum, with perfect lens and perfect mirrors could produce a ridiculously powerful laser, really only limited by the amount of energy put into it. How awesome are fucking lasers anyways?

Ugh, sorry, no. All forms of EM radiation are photons. The only special thing about them is that our eyes are sensitive to them. Also, Lasers dont need to be light - in as much as stimulated emission can produce EM radiation at a range of wavelengths. The same principle has been used with microwaves to make Masers, UV Lasers and in theory could be used for X-Ray Lasers. A Laser can not be a perfect vacuum inside - it needs a resonance cavity with gain medium in it (typically gas or solid state) to actually amplify by stimulated emission - perfect vacuum means no material to emit. The need for a material limits thier power output as energy has to be "pumped" into the gain medium to get population inversion (more stimulated electrons than ground state), which is not an efficient process, typically a few %. Two Perfect mirrors would also be pointless - you need the Laserlight to escape at one end after all.

A soar sail will be pushed along by whatever photons hit it - visible, uv, anything. Most of the high energy stuff passes striaght through one, and the low energy stuff has so little momentum (de Broglie's equation...) it makes little difference unless there happens to be many radio-photons. As for the Sun, treating it like a black body and applying Wien's Law it can be shown that the vast majority of photons from the Sun are at a wavelength of 480 nm - nice and orange. So many infact thatmost other wavelengths become irrelevant.

Physics lecture over. Imma gonna go to work and teach this shit now.
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DWC

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Re: SCIENCE, the Higgs, and everything else!
« Reply #659 on: July 19, 2013, 01:34:18 am »

Even the "light has no mass" people say it has momentum. It is documented and accepted as scientific fact.

http://en.wikipedia.org/wiki/Solar_sail

Bro, electromagnetic radiation includes light, but isn't all like light. Light is special, it's like a particle and a wave at the same time. The only thing a laser uses is light, it doesn't spew out gammas or radio wave or infrared or anything else besides light. The sun spews out everything in the electromagnetic spectrum, including light because it's basically a roiling cloud of hydrogen bombs going off. A solar sail would work because of everything it is sending out (besides light) is causing radiation pressure on the object. Not to mention like, regular thermal energy produced by the sun.

Also, outer space is not a perfect vacuum. The space inside a laser could be a perfect vacuum, with perfect lens and perfect mirrors could produce a ridiculously powerful laser, really only limited by the amount of energy put into it. How awesome are fucking lasers anyways?

Ugh, sorry, no. All forms of EM radiation are photons. The only special thing about them is that our eyes are sensitive to them. Also, Lasers dont need to be light - in as much as stimulated emission can produce EM radiation at a range of wavelengths. The same principle has been used with microwaves to make Masers, UV Lasers and in theory could be used for X-Ray Lasers. A Laser can not be a perfect vacuum inside - it needs a resonance cavity with gain medium in it (typically gas or solid state) to actually amplify by stimulated emission - perfect vacuum means no material to emit. The need for a material limits thier power output as energy has to be "pumped" into the gain medium to get population inversion (more stimulated electrons than ground state), which is not an efficient process, typically a few %. Two Perfect mirrors would also be pointless - you need the Laserlight to escape at one end after all.

A soar sail will be pushed along by whatever photons hit it - visible, uv, anything. Most of the high energy stuff passes striaght through one, and the low energy stuff has so little momentum (de Broglie's equation...) it makes little difference unless there happens to be many radio-photons. As for the Sun, treating it like a black body and applying Wien's Law it can be shown that the vast majority of photons from the Sun are at a wavelength of 480 nm - nice and orange. So many infact thatmost other wavelengths become irrelevant.

Physics lecture over. Imma gonna go to work and teach this shit now.

tl;dr

But seriously, why would the momentum of something matter if it doesn't have any mass?

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Two Perfect mirrors would also be pointless - you need the Laserlight to escape at one end after all.

Yeah that's true. Damn. Still, if what you said before is true, then it would be some kind of immovable object vs unstoppable force type problem, where the momentum of the light (apparently) will work through a perfect mirror (somehow), right? So, i'd be like a laser-pipebomb, right?

Kidding asides, now I'm genuinely curious since I've found I'm ignorant on something I thought I understood. I've heard of masers. Could a 'perfect mirror' act in a 'laser' that works off a higher energy EM wavelength, like Gamma-rays or something? Like reflect a certain portion of it back to another mirror to concentrate it's effects? You mentioned X-ray lasers (xrasers?) is there a physical limitation on the shorter wave-lengths like gamma-rays working asides from them just normally plowing through a regular mirror?
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