news sciences: Comments of the Week #59: From last light to the highest energies [Starts With A Bang]

“Science knows no country, because knowledge belongs to humanity, and is the torch which illuminates the world.” -Louis Pasteur

Well, it’s been another doozy of a week here on Starts With A Bang, and we’ve run the gamut from the far future to the smallest theoretical scales, from Hubble to the highest energies. If you missed anything, catch up on all of the following:

The last light in the Universe (for Ask Ethan),
Disney’s Game of Thrones (for our Weekend Diversion),
The most extreme view into deep space (for Mostly Mute Monday),
The limit of what Hubble can see,
String theory, black holes, and reality (a live-blog of the latest Perimeter Institute public lecture), and
The most energetic particles (for Throwback Thursday).

In addition to all that, I had a new piece appear over at Forbes that the skeptical-minded among you may supremely enjoy:

No, NASA Did Not Accidentally Invent Warp Drive.

You’ve all had your say over here; now let me pick out the best of them and do them justice right here for our Comments of the Week!

Image credit: Janella Williams, Penn State University, via http://ift.tt/10EpghW.

From Andrew Dodds, speculating as to the utility of brown dwarfs in the far future: “I’d guess that if there were civilizations still out there, a brown dwarf would be taken as a valuable prize to be mined and allowing a star to form seen as a great waste.. but I don’t think that can be taken into account!”

You know, it’s interesting to think of what might be of utmost importance out there, in our galaxy’s far future. Would you want the hydrogen from the brown dwarf, what might be a relatively rare element out there? Would you want to dive deep down, inside, and pull out the heavy elements past the sea of metallic hydrogen? Would you want the slow, low burn of deuterium fusion (which happens in brown dwarfs) to keep on going, perhaps outliving the M-dwarfs due to their low luminosity?

Image credit: MPIA / V. Joergens, via Joergens, Viki, 50 Years of Brown Dwarfs – From Prediction to Discovery to Forefront of Research, Astrophysics and Space Science Library 401, Springer, ISBN 978-3-319-01162-2.

I don’t think you would, though. The prospect of using two sufficiently massive brown dwarf to create a true star — a red dwarf — is too great. The brown dwarfs cool down quickly, within the lifetime of our Universe already, and become virtually useless. Honestly, they’re not much better than a Jupiter-like planet after a few billion years, and gas giant worlds are a dime-a-dozen. But consider what a red dwarf is. Where else, other than in a star, can you get a self-sustaining nuclear reactor that emits exa-Watts (look that prefix up, those of you who don’t have it memorized) of energy on a consistent, continuous basis for literally trillions upon trillions of years?

Someone admonished me for my oversight in not coining the term red straggler, as two brown dwarfs merging — and causing the ignition of hydrogen fusion — would be exactly that. On timescales of ~10^15 years and up, this may be our best hope for light in our Universe, and I wouldn’t have it any other way.

Image credit: Anderson Mahanski, of the Mountain (Gregor Clegane) and the Red Viper (Oberyn Martell).

From Denier on Game of Thrones in the style of Disney: “My favorite is of Gregor “The Mountain” Clegane playing a happy game of ‘guess who it is’ with Prince Oberyn Martell.”

It’s very funny you say this, because although the books and the show diverge in a great many ways, the demise of Oberyn at the hands of Ser Gregor is practically identical in both treatments. Make no mistake: Oberyn — like a great many “good guys” in Game of Thrones — is no hero in his own right, he’s merely the “less bad” guy when compared to the mountain.

Still, it’s funny how, given human nature, we always find ourselves taking sides in a conflict like that. It reminds me a lot, honestly, of “The Good, The Bad, and The Ugly,” where all three main characters are bad guys to varying degrees, with no one of them being an out-and-out “good guy.” In the Game of Thrones world, the closest we get to a good guy is Eddard Stark. And what do we get to see of that? We get to see Dark Helmet’s words ring truer than ever:

So, Lone Star, now you see that evil will always triumph because good is dumb.

Image credit: NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team (inset) / NASA, ESA, S. Beckwith (STScI) and the HUDF Team (main).

From Ragtag Media on visible light, infrared and visualization: “I feel that this simple visualization will be lost with the [infrared] [James] Webb one. Does anyone know with the [JWST], how much natural images we will we loose and have to rely on artist renditions?”

Part of the reason these images — like the XDF and HUDF, above — are so amazing is because they already go beyond what we can see in visible light! The HUDF image has two filters in the near infrared, at longer wavelengths than the human eye can perceive (by about 50 and 200 nm, respectively), and the XDF image goes all the way to 1.4 and 1.6 microns, or double what humans can see. You might be used to infrared images looking like this:

Image credit: Chris Fastie, from a link at http://ift.tt/10ZdqJF.

The middle image is false colored, the right image is more typical of what we display. But what’s actually going on in an image? We assign color to various filters, and so it’s only a question of what information we want to highlight. In visible light, we assign violet/blue to about 400 nm, red to 650-700 nm, and fill the spectrum in between. But James Webb will start about at 550 nm (yellow/green), and go all the way to… about 10 microns, or about 30 times the wavelength range that humans can see! (And less well out to about 30 microns, which would increase its range to around 90-100 times what we can see.)

Image credit: NASA / JWST science team.

How we color it is up to us, but if you — for example — like the images that Hubble returns, you can pretty much expect the same. Brian Koberlein wrote a great piece on image colorization for astrophotography that I suggest you check out if you want more information.

Image credit: NASA / Hubble team, via http://ift.tt/1JVrCyI.

From PJ on long-range interferometry: “I wonder, could another be built to use as an interferometer – say, with a baseline of several hundred Km.? Easier to achieve in space than the limitations of land based systems.”

PJ, this is an excellent idea. Wouldn’t you want another James Webb, another Hubble, another anything of your best telescope, to do interferometry? In fact, it’s beyond an excellent idea: it’s the ultimate plan for achieving the highest resolution information available. On the ground, we built a second Keck Telescope a little ways away to do long-baseline interferometry: two 10-meter-class telescopes that can talk to each other across great distances. And we’ve gone even farther than that. Think, if you will, of the aptly named Very Large Array and other incarnations of this based on the same concept.

Image credit: Architectural rendering of the now-completed Magdalena Ridge Observatory Interferometer (MROI) delay-line facility and beam-combining laboratory, via http://ift.tt/1JVrCyN.

Long-baseline interferometry like this is incredibly useful. When you have a big telescope, you can see fainter objects because you can gather more light. You can also achieve higher resolution because you’re collecting light over a larger area. Well, interferometry is like getting the resolution of a telescope the size of your baseline, but with the light-gathering power of the size of the actual telescope. It’s a cheap, practical way of achieving those very high resolutions without breaking the bank to build a monster telescope.

There are synching issues that happen if these telescopes aren’t at a fixed distance, however, which can be overcome, but only with great difficulty and expense. This is, by the way, the very methodology that the Event Horizon Telescope collaboration is using — by combining a huge number of VLBI (very long baseline interferometry) stations around the world — to hopefully get the very first image of the event horizon around a black hole: Sagittarius A* at the center of our Milky Way. Check back in about 8 years, and we may just have that image!

Image credit: screenshot from the perimeter institute live stream.

From four different individual commenters on Amanda Peet’s ~~lecture on String Theory and a few of its more interesting/dubious claims…~~ appearance. Oh.
“If Amanda Peet believes in string theory, then I’m in. She’s got that girl-next-door vibe while smoking hot at the same time.”
“Not the Amanda Peet you’re thinking of, I’m afraid. http://ift.tt/1JVrCyV”
“don’t know if you’re thinking of the same Amanda Peet, but this Amanda is far from hot, in fact, she’s trying desperately to look like a man. … hair.. clothing.. body language…”
“Whats wrong http://ift.tt/1JVrCyV? Is it her knowledge and wisdom that scares you off ? There might be a possibility that not everyone agrees on your definition of hot!”

I don’t know how many of you know this, but there’s a huge, systematic problem that I’ve seen firsthand in physics (and to a lesser extent, astronomy) departments all across the world and in particular all across the United States: the problem that women in this field are judged first for their appearances and then second for their actual merits in the field. In fact, I wrote a lengthy post about this a couple of years ago, one I might have to bring back and revamp for a Throwback Thursday soon.

Why? Because very, very clearly, it’s still a problem.

Image credit: UK National Commission for UNESCO, http://ift.tt/SZVeNO.

It would be super easy for me to ignore these comments and focus instead on something else, like the relevant, work-related comments that you made. But — as someone who both has a unique (and perhaps unusual) appearance and gets to go through life without being harshly judged because of it — I kind of have a responsibility to speak up for those who are judged harshly (and super unfairly) because of theirs.

I don’t think any of you who did this are bad people, and I don’t think any of you meant to make anyone feel bad. But here’s what I want you to take away: every time you do this — every time you pass judgment on someone in any field on anything other than their merits and skill in that field — you’re treating them as though they’re less valuable, intrinsically, than someone who you would judge solely on their skill and merits. If you don’t intend to treat women as though they’re automatically less valuable than men, then don’t pass judgment on their appearance, life choices, or anything other than their merits. It’s that simple, and anything less than that simple, basic form of decency makes this world a less equal place to live.

Image credit: Boyle, P.J. arXiv:0810.2967 adapted from Croninet al.

And finally, one last physics comment, from Andreas on the GZK cutoff and the highest energy cosmic rays: “There’s a thing which was not mentioned in this very interesting article and I’ve been wondering about: redshift. If the ultra-high energy particles have been created millions to billions of lightyears away, due to expansion of space, they should exhibit a much lower energy now than when they’ve been created. I suppose this means that they must originate from somewhere relatively close to us or else the GZK cutoff would have bitten them relatively early, right?”

It’s actually a little more sophisticated than this. Yes, we can assume that if there are particles hitting us above the 5 × 10^19 eV energy threshold — something not observed by the best, most accurate, most recent cosmic ray observatories at all, like Pierre Auger — they must be originating somewhere closer than about 10 million light years distant, otherwise the pion-producing interactions with the CMB photons will strip away energy too quickly.

But what about farther out in the Universe?

Image credits: Earth: NASA/BlueEarth; Milky Way: ESO/S. Brunier; CMB: NASA/WMAP.

10 million years of travel time is nothing compared to the age of the Universe, the CMB temperature or the number of potential energetic sources out there. But there are plenty of active galaxies within, say, a billion or three light years (300-900 Mpc), and even in that time, the CMB temperature was still only about 3.3 K (instead of 2.7 K). The amount of redshift would bring the energy down from ~5 × 10^19 eV to ~4 × 10^19 eV, which again, is almost nothing.

But what’s more effective is the fact that you do have a chance — above about 10^17 eV — of producing an electron/positron pair from a CMB photon scattering off of a proton. The cross-section is very low, but over billions of years, the chances add up. So it’s very likely that the highest energy cosmic rays originate from galaxies that are farther away than 10 million light years but closer than about 2 billion light years, give or take.

Thanks for a great week, and thanks even more for being open to a little constructive criticism. Let’s all do our best to make this Universe the best place it can be, for each and every one of us in it.

from ScienceBlogs http://ift.tt/1EWfKIl