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Noise Pollution

Noise is a recognized form of pollution, but it is difficult to measure because the annoyance or discomfort it causes varies between individuals. There is evidence that hearing sensitivity among young Americans is decreasing because of exposure to noise, including overly amplified music. Apart from hearing loss, excessive noise can cause sleeplessness, ulcers, high blood pressure, and possibly heart disease. A 2005 study found that city residents are willing to pay how much for noise reduction? 

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1 hour ago, oldtexasdog said:

Noise Pollution

Noise is a recognized form of pollution, but it is difficult to measure because the annoyance or discomfort it causes varies between individuals. There is evidence that hearing sensitivity among young Americans is decreasing because of exposure to noise, including overly amplified music. Apart from hearing loss, excessive noise can cause sleeplessness, ulcers, high blood pressure, and possibly heart disease. A 2005 study found that city residents are willing to pay how much for noise reduction? 

 

HONK IF YOU HATE NOISE POLLUTION!

 

Over the last few years, the Missouri Highway Department has been putting up sound barrier walls along heavily traveled highways that run through residential sections.  I made a joke it's like Dolby Noise Reduction for the highway, and I think one person got it.

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Do you remember how to forget?

 

Long Term Potentiation (LTP)  refers to an increase in the response of a neuron to repeated stimuli.  Human memories don't take place in any specific area of the brain, but are distributed throughout.  Taking the example of the memory of your first kiss; how it felt might be stored in one region, while how it tasted in another and how it smelled in yet another.  This results in branches of neural activity, and the more those connections are re-visited, the more they are reinforced.

 

A colloquial term for this phenomena is 'memorization', and it has served the human species very well.

 

Like anything, however, there is a down side, and one is a specific form of memory loss caused by LTP.

 

In LTP induced memory loss, information that is stored adjacent to a LTP branch can be difficult or impossible to recall; the existing LTP connection is so strong that it overwhelms our attempts to recall information that is nearby.

 

This is why recall can be improved by thinking of something else for a bit; it is then more likely that the data at 'the tip of your tongue' can be recalled without being swamped by LTP.

 

Image result for long term potentiation example

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16 hours ago, RichP714 said:

 

Thanks @RichP714, that is a super experiment. And something so simple that should/could be done in every high school physics lab.

 

Imagine working every day for years with a guy that would integrate "discoveries" like this and share them with your entire company?

 

I worked for 16 years at Autodesk, first in Sausalito, then in San Rafael, CA.  John Walker, the author of that article, a founder of Autodesk, now living in Switzerland, and owner of www.fourmilab.ch, roamed the halls and shared stuff like this often. Some fun stories.

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Just How Resilient Is Spacetime?

Just How Resilient Is Spacetime?There was a discussion at the outer rim back ago about different spacial topologies; flat, curved, non-euclidian, etc.  This article gives a number to the malleability of spacetime.

 

A more mathematics oriented view is here:  http://physics.princeton.edu/~mcdonald/examples/stiffness.pdf

Edited by RichP714

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Record confirmed sniper kill 2.199 MILES...

 

In mid-2017, the sniping community was rocked by incredible news: a Canadian sniper team operating in the Middle East had made a successful kill at a distance of more than two miles. The team, deployed to fight the Islamic State, killed an ISIS fighter at a distance of 3,871 yards. The shot was a record breaker and more than a thousand yards farther than the previous world record.

 

On June 22, 2017 the Globe and Mail reported that two snipers assigned to Joint Task Force 2, Canada’s elite special forces unit, had shot an Islamic State fighter in Iraq at a distance of 3,540 meters, or 3,871 yards. The sniper team was stationed on top of a highrise building when it took the shot, which took almost ten seconds to reach its target. The sniper and his spotter had used a McMillan TAC-50 .50 heavy caliber sniper rifle. According to the Globe and Mail, the kill was verified by video “and other data.”

 

To understand the complexity of the shot, it’s best to start with a sniper maxim: sniping is weaponized math. Although a .50 caliber sniper rifle bullet can fly as far as five miles, a host of factors including gravity, wind speed and direction, altitude, barometric pressure, humidity and even the Coriolis Effect act upon the bullet as it travels. Even worse, these effects increase the farther the bullet travels. A successful sniper team operating at extreme distances must do its best to predict exactly how these factors will affect the bullet and calculate how to get the bullet back onto target.

 

The first and most influential factor on a bullet is gravity. A bullet begins to lose energy as soon as it leaves the muzzle of a gun, and as it loses energy it loses the ability to counteract gravity. The farther and slower a bullet flies, the more Earth’s gravity will pull the bullet downward. This is known as “bullet drop,” and even the most powerful bullet, such as the .50 caliber round used by the TAC-50, will invariably experience it.

 

In most shooting shooting situations, bullet drop is only a matter of a few inches or more. The Canadian snipers, on the other hand, had to deal with a phenomenal amount of bullet drop: at 3,450 meters, the bullet would be expected to drop 6,705 inches! Ryan Cleckner, a former U.S. Army Ranger sniper andauthor shows the ballistic data for the shot here. As the bullet is traveling subsonic at a spend of 940 feet per second, the bullet is diving an average of nearly two inches per foot of forward travel, with the problem getting much worse as distance increases.

In order to make the shot the Canadian snipers had to counteract the staggering amount of drop. Being on a highrise building, or hilltop was a must. The rest of the drop correction had to be done within the rifle’s scope, which can be adjusted for drop, and a scope mount that was angled upward for extreme long distance shooting.

 

Cleckner’s data also provides other useful information. Bullet flight time, from the muzzle of the Canadian sniper’s gun to target was just over seven seconds. The bullet was traveling at 940 feet per second when it hit, which means it slowed to below the speed of sound. Finally, after traveling more than two miles the bullet hit with 1,472 foot pounds of energy, greater than most M16 bullets at point blank range.

Another major factor that would have affected the shot was windage. When shooting at extreme distances, even a mild wind of five miles an hour will have an effect on the flight of a bullet, slowly but surely nudging it off its flight path toward the direction of the wind. At 400 yards, a .50 caliber bullet will be nudged 2.5 inches off its path by a five mile an hour wind. At 3,800 yards that balloons to an incredible 366 inches. In other words, the snipers had to assume their bullet would impact just over thirty feet in the direction of wind travel and plan accordingly.

 

https://nationalinterest.org/blog/the-buzz/the-worlds-longest-sniper-kill-the-enemy-shot-dead-3871-24141

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50 minutes ago, PMAT said:

 There are some translation issues there or something. The math is not right. Bullet drop is not 558 feet.

 

 

From the linked article, there's a link to flight trajectory calculations by Ryan Cleckner, a former U.S. Army Ranger sniper and author, the stats are in English

 

https://ryancleckner.com/canadian-sniper-set-world-record-longest-shot-2-miles/

 

His calculations mostly correspond.

 

Also, if the flight took 10 seconds, and gravitational acceleration is roughly 9.8 meters per second per second, and ignoring the horizontal velocity change, the average person calculates a ballpark answer that also corresponds.

 

A ballistic trajectory is parabolic; variables such as elevation change in a parabolic fashion with time.

Edited by RichP714
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55 minutes ago, Daddyjt said:

 

Difficult to fathom, but here’s the chart from Hornaday’s site for the 750gr A-Max....

 

04A1AFCE-6F74-43B8-914D-E73FDA318865.jpeg

 

 

Difficult to fathom, I think mostly because it's outside of the realm of normal experience with a rifle.  I'm not a hunter, but if you sight in at, say, 100 yrds, and attempt shots to perhaps 1000 yrds tops (MAYBE 300-500 USUALLY? idk), the drop is so much less than mentioned above; the thing to remember (for shooters who are familiar) is that parabolic curves are substantially different than ellipses or arcs, and trying to extrapolate a personal experience onto a parabolic path isn't very intuitive unless one has great familiarity with it.

 

 

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What struck me, when I first saw this, some time, back, was the shear amount of time it took for the bullet to travel that distance.

 

Whether we get too take in by movie magic or just don't truly appreciate the distance, the time at first struck me as appearing way too long, but doing the math shows it to be quite realistic, if a bit difficult to grasp.

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I'm not familiar with that instance, but imagine if the target was in conversation with someone, perhaps sitting around a fire.  His friend would see him experience a silent and 'unscheduled disassembly' right before his eyes.

 

Also impressive is the AC-130 gunship; it operates out of visual range; the targets never hear or see anything.

 

Most of the very impressive AC-130 footage is still classified, but there's this on youtube that gives an idea)

 

 

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4 hours ago, RichP714 said:

 

Yes, an incredible achievement; a generous dollop of credit to the weapon and spotter as well

 

Absolutely an incredible achievement.  I have my own experience with long range(to me) shooting of a .50:

 

I own an Armalite AR50.  It’s in the middle to low end of .50 rifles price wise, but still about the price of a couple TFM75 amps.  I also have very nice optics (Nightforce NSX 5.5-22) that cost more than the rifle.  Add in Leupold mkIV rings and a Badger Ordinance 15 degree base (another $350), and I have a pretty nice package. So I decide I was going to go out to the desert west of SLC and pound away at a few 1,000 yard targets. My father-in-law and I stoped at the grocery store and picked up half a dozen watermelons - the big rugby football size ones, not these tiny new ones that are all the rage. 

 

We got out to the desert, and set off from the truck carrying a couple watermelons and my range finder. After walking for what seemed like a LONG way, I stopped and ranged back to the truck. 300 yards. Wow, I would have swore it was farther than that. So we keep walking, and after a while, I turn to look at the truck. It’s a very small dot, so small in fact, that I need a steady rest to range it - 550 yards. So I tell my father-in-law that we are going to shoot watermelons at 500 yards, and see how that goes. We prop them up on a hillside, and trek back to the truck. 

 

Mind you, I’m using perhaps the finest optic one can mount on a .50 BMG rifle, at 22x magnification, on a bipod from prone position. Where my crosshairs meet, they virtually COVER the melon.  At 500 yards. I squeeze off one shot, centered on the melon, just to see how short I am. Surprisingly, I’m only about 6” low, and dead-on for windage (I had previously sighted the rifle in from benchrest at 300 yards).  A little less than a foot (near as I could tell) held over the melon delivered an explosive hit on the second shot. 

 

This experience taught me a few things:

 

1.  The guys that say they shot a running deer with a 30.06 and a 3-9x scope at 1,000 yards are full of it. 

2.  In any shooting system (rifle, optics, ammo, shooter), the shooter is almost always the limiting factor. A great shooter with a marginal rifle will outshoot a marginal shoot with a great rifle any day. 

3.  Trigger control is perhaps the most important thing to master in long range shooting. 

4. Hydrostatic shock is flat-out devastating. We shot melons with FMJ, SP and HP rounds that day. No difference whatsoever in the damage pattern to the melon. The hydrostatic shock of a 650-750gr bullet at 3,000fps was doing the damage. 

5. And perhaps most importantly, the discipline and dedication of a soldier willing to sit for days in the most uncomfortable of positions, watching the same spot of earth, waiting for the right moment, then executing (pun) the most impossible of shots is awe inspiring. 

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28 minutes ago, Daddyjt said:

Mind you, I’m using perhaps the finest optic one can mount on a .50 BMG rifle, at 22x magnification, on a bipod from prone position. Where my crosshairs meet, they virtually COVER the melon.  At 500 yards.

 

you have more large load experience than I do; I think that's the marksmanship USAF medal (for M-16) with bronze star (for 9mm handgun)

 

20191022_174330.png

Edited by RichP714
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12 minutes ago, RichP714 said:

 

you have more large load experience than I do; I think that's the marksmanship USAF medal (for M-16) with bronze star (for 9mm handgun)

 

20191022_174330.png

 

Very cool, I did not realize you were a vet (I probably should have) - thank you for your service. That means you were shooting the M16 before they worked all the bugs out of it.  What were your thoughts on the M9? I have tried multiple times, but I just can’t get to where I love to shoot one. As big as my hands are, the grip of the Beretta is just too chunky for me...

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37 minutes ago, Daddyjt said:

 

Very cool, I did not realize you were a vet (I probably should have) - thank you for your service. 

 

It was my pleasure.  I was in the USAF and DoD for 19 yrs, 8 months before being medically retired, and loved it.  Most people probably like to feel useful, and I was lucky enough to have had two meaningful careers.  In the scenario above, I would have been the spotter rather than the shooter.  I first was working in the precision meaurement lab in Okinawa (in support of the F-14, F-15 and F-16 avionics systems), and ended up working XX feet underground on imaging systems for surveillance satellites (specializing in digital push broom sensors).

 

37 minutes ago, Daddyjt said:

That means you were shooting the M16 before they worked all the bugs out of it.  What were your thoughts on the M9? I have tried multiple times, but I just can’t get to where I love to shoot one. As big as my hands are, the grip of the Beretta is just too chunky for me...

 

I'm sorry, I have only a vague remembrance, it was so long ago.  Yes, the M-16 wasn't quite as sorted out as it ended up later; I remember it stove piping often.  All I remember of the M-9 is that we had to be trained on it before deployment to Iraq, which was a good motivation to pay attention.

 

I can no longer shoot even a BB gun these days, my left side never quiets down enough (micro-tremors) and my brain can focus on one sight or the other, but not both.

 

I remember before my dad passed, my brother took us to a shooting range in NY; he had a very nice rifle (which I didn't shoot) and a few handguns.  WE ended up having more fun shooting at a can we saw laying on the ground at the far targets (no idea what the distance was).  I remember taking a blind shot, out of frustration, because the front and rear sights kept swimming in and out of focus, and my body wouldn't be still, but that can leapt into the air (a lucky shot).

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