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Huge Lenses To Observe Dark Energy
Iddo Genuth writes "UK astronomers, as a part of the Dark Energy Survey collaboration, have reached a milestone in the construction of one of the largest ever cameras to detect dark energy by completing the shipment of the glass required for the five special lenses. Each step in the process of completing this sophisticated camera brings scientists closer to detecting the invisible matter that cosmologists estimate makes up around 75% of our universe."
If it is detectable in any way, it's not "dark" anymore!
Wouldn't it be better to call it an effort to "define" dark energy?
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They're making it sound like dark energy is visible light. If it's "dark" that means it's undetectable by normal means like giant lenses for instance. How could you just see dark energy? Isn't it more like something you'd detect with sensors, not a giant lense? But no, straight out of the article, they're gonna use it to for "detecting the invisible matter" because it has "advanced optics." Btw they said MATTER, not energy so apparently that's what they're actually looking for. Well that would officially make it dim matter, wouldn't it? Like I always thought, dark matter is just matter without a whole lot of light shining on it cuz it's in between galaxies and stuff.
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Hurry Quantum boy, get into the dark energy mobile...
[Presses Big Red Button]
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Narrative: Somewhere on a distant planet
Astronomer "Did you see that flash, hah proof dark energy doesn't exist"
I know that planets aren't considered dark matter but I always wonder if the scientists out there are taking into account all the planets and asteroids out there that we cant see. I mean every other day, it seems, I'm reading about new gas giant planets detected around distant suns and the articles always make out as if its a surprise to the guys who found it. Is it possible that we might have underestimated the amount of planetary debris that we just can't see with current telescopes?
+++ America Nonline Chatroom +++ SciPhyGuy1933: Hey, my calculations don't make any sense... it seems like there should be more mass at the center of this galaxy I'm observing. Iwonbensteinsmoney: Do you realize what this all means?!?! Everything we used to know about science and all of our formulas are flawed! Egad! Cutiebaby2x0x0: Oh you boys.. just do what I do when I don't know the answer to something. Just make something up.. SciPhyGuy1933: That's the most prepost.. er.. wait... she might be on to something dude.. Iwonbensteinsmoney: Will you marry me?
Dark energy may be an indicator that we live in a false vacuum. If this is the case and the true vacuum is speeding towards us with the speed of light then we are doomed. So, add another doomsday scenario to your list.
Government cannot make man richer, but it can make him poorer. - Ludwig von Mises
scientists needing huge optics 8-) whood a thought it
sorry for my comments, I'm drunk
I did not find TFA very illuminating. Of course the topic was optically sensing the effects of Dark Energy which doesn't radiate, so maybe I wasn't supposed to be illuminated.
Invenio via vel creo
just getting a higher res snapshot of the visible universe so they can 'guess more precisely..?!'
There are explanations other than "dark matter" and "dark energy" that can explain the observations we see. MoND, for example (Modifien Newtonian Dynamics) is a quite popular theory among physicists, and it does not require that we believe that most of our universe is basically undetectable by humans.
Occam's Razor works strongly in favor of MoND over such hypotheses as dark matter... only time will tell.
If you smash your car into an invisible wall on a freeway, I'm sure you would be surprised since you didn't expect it. On the other hand those who are looking for invisible walls on freeways would be able to spot your lone smashed car on the freeway with their massive telescope and take a closer look.
They are trying to find that lone smashed up car in space.
Easy. All you need is an Amber Spyglass.
But for many years the biggest mirror was the 200-inch Hale Telescope at Palomar Mountain near San Diego. Nowadays there are several monolithic 8-metre mirrors, and the two 10-meter Keck telescopes atop Mauna Kea, Hawaii; they are composed of carefully aligned hexagonal subsections.
Why the big disparity?
With a lens, you have to grind and polish both sides, and what's worse, a single lens won't do because all glass refracts different colors differently, giving rise to chromatic aberration. A minimum of two lenses is required, for four surfaces to fabricate.
For both lenses and mirrors, the tolerance of the surface is a small fraction of a wavelength of light across the whole surface. But for lenses, all the surfaces must also be very accurately parallel.
But really the worst problem is that with a lens, the light goes through the thickness of the glass. The glass must therefore be very uniform and free of internal stresses that could alter the index of refraction in different places.
Such glass is very difficult to make; no doubt these lenses are only possible because of recent advances in optical glass manufacture.
That's not a problem for mirrors; observatory telescopes use "first-surface" mirrors, which are aluminized on the front, so the light doesn't go through the glass. Mirror glass therefore doesn't need such careful tolerances.
But my guess is that they are using lenses because they have a much wider field of view; it's quite easy to make a lens with a sixty degree field of view, but with a mirror the field of view is typically a fraction of a degree. With small amateur scopes, the maximum field is about a degree, twice that of the full moon.
That seems clear from the photo, because of the steep curvature of the glass; wide-angle lenses usually have very strong curves.
And yes, I know what I'm talking about - I'm an avid amateur telescope maker, and at one time was a Caltech astronomy student. I've published in the Astrophysical Journal, and have done observing runs at the Palomar 60 and 200 inch telescopes.
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Maybe this camera will be able to see the dimension where all those lost socks go to...
- Just a thought
How big are their ants?
"Damn, I dropped my contacts again. Oh wait, here they are. Hmmmm, they seam bigger for some reason...."
Table-ized A.I.
You can't observe dark energy or dark matter. They are fill in terms for unobserved matter and energy that must exist based off our limited observations, but we can't see.
I'm of the mind that neither exist and are kludges to stop the leaky pipes of modern science from falling apart, because key parts of our understanding of Cosmology and Astronomy are just plain WRONG.
Burn Hollywood Burn
Each step in the process of completing this sophisticated camera brings scientists closer to detecting the invisible matter that cosmologists estimate makes up around 75% of our universe.
I thought that 75% had already been identified as the Microsoft tax.
Is that what you get in a Dyson sphere?
P.S. re: your sig, I'd say Dick Cheney is living proof that government can make man richer, provided we're talking about the right man...
Soylent Green is peoplicious!
So how do they do it? You could spray some varnish (or whatever) on it, but then it wouldn't be first-surface anymore.
you can't observe charge because it is a fundamental force of nature, but i've never read a textbook that listed dark energy a fundamental force.
The title of this story sounds like a description of a nerd leaning into his monitor to stare at goatse...
There is a fine line between being a cultivated citizen and being someone else's crop. - A. J. Patrick Liszkie
You can't really make very big maksutovs. You can make big schmidts - there is a 48-inch one at Palomar that is used for all-sky surveys, but they have a very practical problem that the focal surface is a very strongly curved sphere!
It's very easy to make a lens that has a wider field than a schmidt - any wide-angle 35mm camera lens is an example; what's hard is to make it big so it can capture a lot of light, and so see faint objects.
What I wonder about the camera in TFA is what they are going to use for a sensor? If it were a photographic plate, it would need to be eight feet across or so. What would work better would be a CCD that big - but making one would be a big job! No doubt it will be composed of many smaller ones.
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That's somewhat incorrect, and makes a hash of two unrelated things too:
1. Dark matter. Unlike what its name might imply, it isn't dark as in "light absorbing". It's dark as in, it doesn't interact with light at all, except through gravity.
It's only "dark" in the same way as a sheet of glass is dark against the night sky.
But even that metaphor is misleading. "Dark matter" is just a name for a lot of mass that should be there according to calculations (or our understanding of gravity is completely broken at large scales), but hadn't been observed. It's just a funky name. It doesn't mean it's actually dark in any form or shape.
The best example of a scale where this is visible is inside a galaxy. With just gravity determining the speed of rotation around the centre, the stars closer to the centre should rotate faster than those on the edges. (In the same way as Mercury rotates around the sun once every 0.24 years, Earth in a year, and Pluto in 248 years.) But galaxies don't seem to rotate that way. They rotate more like a solid texture, so to speak. So there must be some mass distributed through the disc, in addition to what we see.
But again, the whole point is that we can't see it. If it were just a cloud of pitch-black baryonic matter, that would actually be easy and comfortable. We'd just do what you said: look at what happens to the light of stars behind it. Since it's plenty of it inside a galaxy, we have plenty of stars to look at and notice if something like that was between us and them. But all we can see is some extra gravity, with all that involves for both star movement and gravitational lensing.
A much more accurate name would be "completely transparent matter."
2. Dark energy.
This is an even funnier concept. With all that mass in the universe, there's gravity all around. Duly noted, the gravity pull of a hideously distant galaxy is really tiny, but it's there. The universe expansion should slow down as gravity pulls everything towards the centre. The funny thing is: it doesn't. It's actually accelerating, and weirdly enough, the farther something is, the faster it seems to accelerate away.
There is _something_ that pushes stuff away from the centre, and it's not like any force we already know.
It's also something we'd be hard pressed to reproduce in a lab. Whatever it is, it's insignificantly weak at small ranges, and only starts to matter at very very very large distances. Even at galactic scales (hundreds of thousands at light years) it seems to do practically nothing at all, but move a few _billion_ light years away, and you start seeing whole galaxies accelerating away. It's not something you can reproduce in a lab.
It's also weird in that a normal energy (e.g., the potential energy in a compressed spring) would get used up, or rather converted into work, as it pushes stuff away. So the force would logically diminish. This one only seems to grow stronger.
So basically this big "WTF?" is what's called "dark energy". There's some energy that's pushing the universe apart, but we don't know what it is, and how to detect it.
A polar bear is a cartesian bear after a coordinate transform.
In that respect it's completely different from iron oxidation.
The other way is to overcoat it with something tough and transparent; traditionally silicon monoxide was used.
One can both protect the aluminum and enhance its reflectivity by giving it multiple layers of tough, transparent minerals. Interference effects cause it to reflect better than aluminum would alone.
That's how laser mirrors work - they're not aluminized. It's the same principle as antireflective coatings on camera and eyeglass lenses, but a different choice of refractive indices and thicknesses causes it to enhance rather than cancel reflections.
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Memo to self: must get out more. Also, must try harder not to trivialise serious subjects.
From scarped cliff or quarried stone she cries "A thousand types are gone, I care for nothing, no not one."
Even if we are living in a false vacuum, it is possible that we can have numerous even infinite numbers of instances of truer vacuum speeding towards us without consequence. That's because the part of the universe we're in would be expanding at a slow but consistent rate. So as long as all instances are far enough away that they're recessing from us at faster than the speed of light, we're ok.
Beware of the Dark Side of the Force
Wouldn't it better to assume that current, so called "mainstream" Gravity Theory is flawed?
We need new, better Physics to explain these things properly. Something like Heim Theory in which gravitation is repulsive for great distances:
http://www.engon.de/protosimplex/posdzech/px_g_gravi1e.htm
Also cosmic red shift can be explained now as a gravitational effect, and not as Doppler effect.
Because of equivalence of mass and energy Heim says there must also exist a field mass of the field energy of each field. However in case of gravitational field this results in a secondary (very weak) additional gravitative source because a field mass possesses its own gravitational field. Mass is producing a gravitation effect, as it can be described with Newton's approximation. Heim says that the energy of this gravitational field corresponds its own field mass. This field mass again produces a second additionally gravitational field which is very weak. Again this field possesses its own field mass which produces a field. So you receive an infinite series, which however converges very fast against a calculable limit value.
The whole description results in a short mathematical description for a corrected gravitation law, which corresponds with Newton's gravitation law within the observable area of space. However for very large distances it will provide completely different results. For very long distances graviton will produce a weak repulsing force which will only exist if a mass is moving toward the centre of the gravitational field. Among other things the phenomenon of the cosmic red shift can be explained now as a gravitational effect.
... different from "dark matter"?
To my knowing, the concept of "dark matter" existing out there wasn't enough to explain a supposed minimum mass of the universe (to allow for it to turn around and re-contract again, some time in the future) and then, in addition, "dark energy" came into the arena?
Just asking.
But then, IANAA (I am not an astronomer, and sometimes very sorry about it) ;-)
... missing matter? Per reviewed: http://www.journals.uchicago.edu/doi/abs/10.1086/588582 Fulltext: http://arxiv.org/abs/0803.4164
Occam's Razor is actually "Entia non sunt multiplicanda praeter necessitatem", and it means (roughly, in English): "Entities should not be unnecessarily multiplied." Whether that means "including fewest assumptions" or "introducing fewest complications" is rather a matter of interpretation, or even just wording. I think we both have the gist of the idea, and that arguing about points any finer is, well... pointless.
I wasn't. Do you see any argument there?
I'd say a basic electro-dynamic model explains everything far more simply and produces far less surprises.
No; plasma cosmologies do not explain "everything" as in "all observations to the present date", period. Dilettantes who both 1) are unfamiliar with the body of observations in astronomy and astrophysics, and 2) botch the application of simple physics (simple, but outside their realm of training and understanding) write word-heavy, physics-lite books about it anyway.
It isn't perfect, but it matches what we see far better than the "96% dark stuff" theory.
Even if it did (it doesn't, as I already mentioned), it would be disingenuos to say that standard cosmology was mostly wrong based only on missing mass or energy. Standard cosmology takes into account all our observations about the universe, from orbits to kinematics to thermodynamics to fluid mechanics to quantum effects to electromagnetism to gravity and everything in between, breaking down only at the extreme end, at our observational limit. Plasma cosmology, and especially the joke that is the particular "Electric Universe" flavor, fails to account for the majority of physical observations, and even its purported explanations fail through misapplication of electromagnetism in the first place.
And before you even imagine that my suggested theory has ever been "proven" wrong, I will tell you the two biggest ways in which attempts to prove it wrong have failed:
Just because you mount a pre-emptive attack against certain arguments doesn't make those arguments incorrect. You're doing something called "poisoning the well"; look it up.
1. They almost always attack assumed properties of an electro-static model (i.e. not the model in question).
There is only one set of governing laws describing electromagnetism. When somebody misapplies these laws, there is no way to resort to "special pleading" because there is only one theory which describes electromagnetism.
2. The "flaws" they point out are actually accurate representations of what happens in a plasma.
No, precisely the opposite is the case: "the flaws they point out" are places where "Electric Universe" relies on inaccurate descriptions of plasma and electrodynamics. The main physical requirement of the Electric Universe is that plasmas can maintain charge imbalances. But they cannot, because the charge carriers are mobile and interact strongly through both attraction and repulsion; this is well-understood and has been for a very long time now. Plasmas don't maintain charge imbalances between any two points further appart than a certain characteristic disntance. This is a failure at a basic level of physical application, and there are other similar basic failures of application.
Also, an electro-dynamic model can and has made accurate predictions where the "96% dark stuff" failed to (and was "shocked" and "surprised). This happens almost every time they get better data from comets (most notably when they smashed into one).
I think you're alluding to Wallace Thornhill's non-prediction(s) pertaining to the Deep Impact experiment, but you're being intentionally opaque by not mentioning it. Thornhill (and Don Scott, as I recall) generally made predictions so broadly defined as to be meaningless, and were still contradicted by the experiment in ways they didn't know enough to whitewash before or after making the predictions, again because of a lack of familiarity with the relevant observational techniques and/or an indirect and/or incomplete application of physics to those observations anyway. So no such "accurate predictions" were made in that case, nor in other cases involving comets or anything else in the universe, one of which you allude to shortly.
And a scientist was able to actually produce "tiny galaxies" in the lab
A couple of posts ago, I went out of my way to point out that we were basically AGREEING, and you call it nitpicking. Well, go stuff it. I have no use for conversation with somebody who wants to make an argument out of nothing.
If you don't understand that, then there is no point in conversing anyway. Goodbye.
http://outrafisica.blogs.sapo.pt ,coherent, model is born.
a new model is beeing released, and explained in simple words and simple math, that will show the how and why.
dark matter, dark energy is only a matematical construction and never will be found. Physics is, for the time beeing, detached from reality. a model that needs to invent 96% of the universe is a huge mistification.
MOND doesnt provide answers. Dark matter and dark energy are invented to fit data to an insufficient, incomplete, wrong model.
the actual model must be droped and a new
in that blog there is new science, irrefutable under physics, logic and math.
(it is in portuguese language, and so you must find a translator, and start reading from oldest to newest post).