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at 8-10 feet, a person with 20/20 vision can not make out better than 1080p on a 60" screen

This is easily verifiable. The standard definition of "normal" visual acuity (20/20 vision) is the ability to resolve a spatial pattern separated by a visual angle of one minute of arc. At 12 inches, the normal visual acuity of the human eye is 0.00349 inch. That means that at 10 feet, someone with 20/20 vision can resolve 0.0349 inch. 1920 (1080p width) times 0.0349 inch is equal to 67.008 inches, significantly wider than a 60" diagonal TV screen.

However, the kicker is in the definition of "normal". 20/20 is actually "the lower limit of normal or as a screening cutoff" (see here; original source link no longer works). From the same paragraph, "the average visual acuity of healthy eyes is 20/16 to 20/12". That means that it wouldn't be very unusual for young healthy eyes, definitionally better than average but by no means uncommon, to be 20/10 or even better.

At 20/10, you can clearly easily distinguish between 1080p and 2160p ("4k") on a 60 inch TV screen at 10 feet. In fact, you could at least begin to make out a difference even in the range of 20/16 to 20/12.

If grandparent wants to say 20/20 vision "sucks", that is arguably a fair characterization in relation perhaps to his own vision, and likely that of fellow enthusiasts. Even his claim that the difference is obvious to "most people" is at least somewhat supportable if you accept that the average of "healthy" eyes is 20/16 to 20/12. At worst he would need to qualify the statement by excluding those with ocular disease or fairly advanced degeneration due to simple aging.

It's not the mass per se which blocks sound. It's the density change. Going from low density to high density or vice versa (assuming speed of sound in the medium is proportional to density) reflects a large portion of sound wave back.
http://www.ndt-ed.org/EducationResources/CommunityCollege/Ultrasonics/Physics/reflectiontransmission.htm

So if you and the noise source are separated by a one-inch thick solid concrete wall, splitting it into two half-inch concrete walls and putting a layer of foam in the middle would reduce the amount of sound transmitted. (The foam tends to absorb the reflected sound energy, so less of the reflection does a second bounce.)

It is far too simplistic to say that "X-Rays can't penetrate metal."

X-rays are absorbed by a material by interacting with the electrons around the nucleus (or with the nucleus itself). This is a statistical question - X-rays will penetrate a short distance into a material. the more dense the material or higher energy (frequency) of the X=rays, the less they will penetrate. See for example
here.

There is a table at the bottom of penetration depths through lead as a function of energy of the X-rays.

>>I suggest you do a search for "cumulative radiation."

The FDA uses cumulative radiation exposure because they don't have any better metric. They already know it's a flawed measure, but nobody is sure where the threshold lies, so they don't use one. For example: http://www.ndt-ed.org/EducationResources/CommunityCollege/RadiationSafety/biological/stochastic/leukemia.htm

While you might like to pretend that 1 rad a day is equivalent to 365 rads one day a year, it's not, as common sense should tell you.

The standard definition of normal visual acuity (20/20 vision) is the ability to resolve a spatial pattern separated by a visual angle of one minute of arc. Since one degree contains sixty minutes, a visual angle of one minute of arc is 1/60 of a degree.

[...]

When visually inspecting an object for a defect such as a crack, the distance (d) might be around 12 inches. This would be a comfortable viewing distance. At 12 inches, the normal visual acuity of the human eye is 0.00349 inch. What this means is that if you had alternating black and white lines that were all 0.00349 inch wide, it would appear to most people as a mass of solid gray.

In case you wondered: a pixel 0.00349 inch wide gives you 286.5 pixel per inch

That would only work if the material were ferromagnetic, or at least highly diamagnetic or paramagnetic if you could generate an immense field (we're talking about yank-the-aircraft-carrier-into-orbit fields). Alas, most materials used in spacecraft are aluminum, titanium, or other non-ferromagnetic materials.

Good writeup. Found a simplified reference with a picture. I'm visual, don't you know ;-)

http://www.ndt-ed.org/EducationResources/CommunityCollege/PenetrantTest/Introduction/lightresponse.htm

In terms of raw sensitivity, green produces the most signal at the lowest intensity. I've personally found that is true, and green on black is my usual choice; I've tried them all, yellow is next best, which also fits the curve.

As PP points out, though, the visual system is complex, and the receptor distribution will vary for each person. It's also been found (no reference, sorry) that most people read words as a chunk, not by resolving and assembling the individual letters, so choice of font and kerning probably has more to do with readability than the color of the text.

And what type of detectors are they using? I did radiological controls quite extensively in the US Navy until about 10 years ago. Unless the detection technology has advanced by many many factors in size and sensitivity since then, I am calling bull on this. There are many things that do not add up here. The size of a radioactive source to be detected above background at 20-50 feet away would be enough to kill something quickly, specially a point source like this (the source is a single point, not a large plane or wall). Radiation levels follow Newton's inverse square law and drop at a rate of 1/r^2 (the inverse of the distance squared) (here is a reference to that). You can do the math but counts above background would be negligible at anything more than a few feet.

I don't typically wear a tin foil hat but I would not doubt someone made this story up to raise awareness that someone somewhere may be watching for radio activity on the highways and if you plan on bringing them in from Canada, you might get caught.

When you pull figures from your arse, you don't actually add anything to the discussion. All that we've learned is that your arse is rather large, and you are used to removing things from it.

Even if your (incorrect assumptions) were correct, 36" x 20" at 1000dpi would be 36000 pixels x 20000 pixels = 720M pixels. Clue: dpi is a scalar measure rather than area.

Of course, the human eye does not work anything like that. Rather than farting numbers I spent 10 seconds on Google to find this which looks into the question of Visual Acuity. The "high-res" part of the eye is a very small circle with about 120 "dots" across its diameter.

As we do not resolve entire "frames" in a single go, the concept of a frame-rate is completely ludicrous. Your argument earlier in the thread about observing skipping when seeing a high speed stimuli doesn't show evidence of a *periodic* frame rate. It just shows that there is a *minimum* temporal resolution. One does not imply the other, especially when the eye is processing asychronous input (from rods and cones).

Although you don't believe that the brain fills in the missing images with educated guesswork, we've already established that what you believe is shit. Most (if not all) neuroscientists have accepted that the high resolution continuous visual imagery that we see is mostly an illusion produced by the mind. There are many well reported experiments that provide evidence of this. You should look for anything on Visual Illusions - there are far too many decent results in peer reviewed journals for me to spend time looking for you. Change Blindness is a related phenomena.

Finally you've cooked up some stupid figures for the number of cells in a brain. Why do you feel the need to demonstrate how stupid you are? The actual numbers (which you get wrong by 3 fucking orders of magnitude) are in the summary of the article! How hard is it to read the 100 billion neurons at the top of the page.

So next time you feel the need to pontificate needless about something that you don't know anything about. Don't. You, sir, are a thief of oxygen and your pointless ramblings have made everyone reading this article collectively dumber.

PS Feel free to mod me flamebait, as I am clearly annoyed. But when you do so remember that the everything the parent poster wrote was incorrect and that I have pointed out to him where he is wrong.

No, they're not just guesses. If they were, you'd have a point, but the amount of C14 is measured from samples of known age. Counting down ice cores and tree rings allows scientists to create a catalog of what the atmosphere's C14 levels looked like over the years. You say they're just guesses, but in reality, quite a lot of work goes into standardizing the data. As I said before, though, there are other methods that are even better because they are able to self-check for problems like the ones you describe.

Sure, scientists can look at what historically has been, but remember, an ape, a tree, and ice absorb C14 from the air. Each specimen will breath in a different amount of air giving a different original amount of C-14 So, even though hours of research have gone into it, they truly are little more than just assumptions. If you'd like some evidence to back this up, here it is: "Radio-carbon dating is a method of obtaining age estimates on organic materials. The word "estimates" is used because there is a significant amount of uncertainty in these measurements.......The C-14:C-12 atmospheric ratio is known to vary over time and it is not at all certain that the curve is "well behaved."" Here's the Source

I've said this before in these discussions and I'll probably say it again but, please show your work. Don't take it personally, but the assertion you just made is far too handwavy to be taken at face value, and as far as I know, quantum mechanics gives us no theoretical reason for this to be true in the temperature regimes you're talking about. As far as I can recall (and I don't have copy of Dalrymple with me, so please forgive me from working from memory), changes of over 1000 degrees C don't seem to alter C14's decay constant. I seriously doubt that a few degrees C are going to do it under normal Earth conditions. If you have some numbers to show, I'd be interested.

I'm sorry for the confusion here, what I meant by decay was non-radioactive decay. "In early September, British researchers reported that warmer temperatures were causing the soil to heat up and dramatically increasing rates of decay. The temperate forests and fields of the United Kingdom are becoming, in essence, semitropical." Here's the Source I was simply trying to point out that the earth is constantly changing and we can not just assume that processes are always occurring at the same rates. And since science is based on observation (look at the scientific method), observation is necessary to prove something. In this case, since the half-life of C-14 has been CALCULATED to be AROUND 5700 years, we can't actually observe the full length decay and thereby can't prove that it doesn't fluctuate over time.

It should be noted that ad hominem isn't Latin for, "That was a mean thing to say!" I suggest that if you'd prefer that your physics be taken seriously, start doing some calculations and stop inventing physical laws that don't exist. I was already a bit grouchy when you responded to me, and you did so by essentially calling thousands of scientists incompetent, stupid, or frauds. You can't seriously think that the objections that you're bringing up have gone unnoticed by the scientific community until now, can you? Obviously not, so they must either be too thick headed or incompetent to understand them, or the entire community of atomic physicists is involved in a conspiracy to defraud us. I'll leave it to you to decide which one you were suggesting.

Actually, for those latin scholars out there, Ad Hominem literally means "To the Man" it is when an argument is focused on a person rather than their argument and it's considered a logical fallacy. Radiometric

You'll find an example CCD distribution for Sony's ICX285AL CCD on page 8 of the PDF. By comparison, the human eye's response looks very different, with different receptors in each case picking up what is nominally the same colour.

You are correct, this would be horribly expensive. I think I may have mentioned that myself, in my original post. :) It would double the cost of the machines and quadruple the cost of ink. At least. It would also halve the effective throughput.

First there's distance. Newton's Inverse Square Law tells us that a radiation source 1" from your nads is going to be nine times stronger than the same source 3" away, or 144 times as strong as a foot away.

Then as you move the phone occasionally has to establish the appropriate tower to contact. In an urban area, you have quite a few metal obstacles which move around you or you yourself move around, making the phone more active. In an urban area you also have quite a few other phones fighting for contact with the same towers, also requiring your phone to increase activity.

If contact is bad then the phone tries with a stronger signal and more often. Note that being in a car, a train, or other metal container hinders contact -- and reflects the signal back at you.

So commuting, you're getting a solid dose of radiation.

Ack! For those of us who actually work with water-borne polymer systems, there's an incredible lack of detail here. One of the challenges in getting a coating that's easily removable is making a polymer system (either solution, emulsion, or dispersion) that forms a highly uniform, cohesive, and integral film that doesn't have a great deal of affinity (either physical or chemical) for the surface to which it's applied. Aside from wondering what the polymer technology is, I have to wonder how much of this is surface-specific.

Did they rely on an application surface that has a very low surface energy? If so, what happens when the car's "original" finish has either a lousy morphology (non-smooth) and/or a high surface energy (overcomes surface tension of the applied liquid - think water beading on a waxed car [low surface energy] versus water "sheeting" on raw steel)? Did they solve the problem strictly through polarity or specific adhesion, and if so, what happens if the "original" finish is of a different chemistry?

And the polymer - maybe they relied on one that has high cohesion but lousy adhesion. Okay, but if it's a hard/high-modulus polymer, how does it not flake off easily? If it's a softer polymer, then how does it not stretch or sag? Tough to do when you're not relying on adhesive bonding to the substrate to help with structure.

Too many questions, and not enough answers in the linked docs or in a Google search. Fooey.

If all you care about is listening to music it really doesnt matter what you get.

I have to disagree. The audio quality from one player to another is not always equal. Creative Labs' Nomad Zen NX (and some other Creative players) have the highest (meaning best) signal-to-noise ratio of the players I've looked at. (Though I still bought an iPod.)

And based on the reviews I've read about other certain players, the firmware and/or hardware is unresponsive at times causing the user to wait up to 10 or 15 seconds for the UI to "catch up" to their command input. And if the player doesn't have enough cache, you could be waiting a second or two between tracks while the new song is loaded into memory.

It's well known; as our eyes drift to the blue and red end of the spectrum, we lose our sensitivity, off by many orders of magnitude from say, yellow. This is why you see blue, and more commonly, red, lights as "night" light sources.

The general reasoning: our eyes evolved with a single primary light source: the Sun. Which has quite the yellow tinge to it. Our eyes adapted to this, and as such, gave yellow the highest sensitivity and drifted off in a rough bell curve from there.

It was an interesting article, and certainly put the RGB sensitivity into perspective, but ... it's not entirely new or surprising, either. Nor does the human eye really respond at RGB -- its response curves (beta, gamma, and rho) more closely correspond to blue, green/yellow, and yellow/orange.

That all being said, thanks for letting us meet Traci. ;)

Switching to metal gates and high-k gate dielectrics also eliminates phonon scattering. Increasingly, the atoms inside transistors are vibrating. Incorporating high-k gate dielectrics alone does not solve the problem.

"This slows down the mobility of electrons," David said. "The metal gate seems to act like a sink for this phenomenon."

David, however, declined to identify what metals Intel is experimenting with. AMD is working with nickel in its metal gates.

So it's all a bit over my head, nickel certainly conducts electricity but obviously not like gold and at an atomic level maybe it doesn't matter... since the silicon is like 4 or 5 atoms thick, and the metal seems to be some sort of a sink for lost electrons.

Physics PhD to the rescue?