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Comment: Re:"the Phoebus cartel still casts a shadow today" (Score 1) 594

by cthulhu11 (#48030595) Attached to: The Great Lightbulb Conspiracy
For sure there are many crappy CFL's out there. When you buy a twisty CFL for 25 cents at a drug store, you get what you pay for. My Cree-manufactured recessed retrofit LED's are doing great, they were like $25/each at Home Despot courtesy local utility subsidy. Unfortunately that only covered the 2700K models, but my wife insists on yellow light anyway.

Comment: Re:There Ain't No Stealth In Space (Score 1) 427

by khasim (#48027291) Attached to: The Physics of Space Battles

The assumption here is that the exhaust is in the form of a gas.

Okay.

Once it passes through the constriction of the rocket nozzle, it expands (the effect is to turn thermal random motion of the particles of the exhaust into directed velocity).

Explain how "it expands" does not equate to expanding beyond the boundary of the shielding.

After leaving the bell, there are no more restrictions to expansion of the gas aside from the small amount of matter in space.

Again, explain how "it expands" does not equate to expanding beyond the boundary of the shielding.

And how it cools to background radiation levels BEFORE "it expands" hits the shield boundary.

Because THAT is the issue you've been skipping.

And again, so what?

Because "stealth" probably does not include "dying of old age 200 years before getting out of your own back yard".

Then use physics to make that argument not assertions that I brought up Voyager.

I already have. But you keep skipping over it. I just did it again at the beginning of this post.

Here it is again:
PHYSICS says that the exhaust will expand. Eventually the exhaust cloud will be larger than the area covered by the "shield". At which time the exhaust will be visible.

You claim that the exhaust will cool to the same level as the background radiation before that. Yet you do not explain HOW it will cool that much.

You keep confusing "cool" with "background radiation". Going from 3,000 K to 2,000 K is "cooling". But 2,000 K is not the same as "background radiation".

Stealth isn't perfect. It would be relatively hard against large, sensitive detectors.

Then it is not "stealth".

You are not "invisible" if you depend upon the enemy being blind.

Comment: Re:Thai Tasting (Score 3, Interesting) 94

by Rei (#48026993) Attached to: Robotic Taster Will Judge 'Real Thai Food'

While I personally see a device like this (sorry... ROBOT!) of rather limited use for testing prepared dishes, I can see great utility for it for testing ingredients. You could have a standardized, unambiguous way to rate the quality or at least properties of a given product, be it meat, fruit, vegetables, etc. I bet cultivar breeding programs in particular could really benefit from this - "Well, I was hoping that this new mango would be a huge innovation, but actually it's almost identical to a Keitt. Though to be fair its mouthfeel is somewhat like a Carrie, and it does have a small amount of a new novel aromatic compound..." Just a single mass produced sensor package that measures a wide range of different properties at once in a repeatable, universal manner. If such a thing could become widespread, I'd bet half of the "cultivars" out there would pretty much disappear, having been shown to be essentially identical to others.

Technology

Robotic Taster Will Judge 'Real Thai Food' 94

Posted by timothy
from the what-about-best-barbecue? dept.
HughPickens.com (3830033) writes The NYT reports that Thailand's former prime minister, Yingluck Shinawatra repeatedly encountered a distressing problem while traveling the world: bad Thai food. Too often, she found, the meals she sampled at Thai restaurants abroad were unworthy of the name, too bland to be called genuine Thai cooking. The problem bothered her enough to raise it at a cabinet meeting. Even though her political party has since been thrown out of office, in a May military coup, the Thai government is unveiling its project to standardize the art of Thai food using a robot. The government-financed Thai Delicious Committee, which oversaw the development of the machine, describes it as "an intelligent robot that measures smell and taste in food ingredients through sensor technology in order to measure taste like a food critic." Thailand's National Innovation Agency has spent about $100,000 to develop the e-delicious machine. The e-delicious machine has 10 sensors that measure smell and taste, generating a unique fingerprint (signature) for each sample of food that passes its digital maw. Generally with electronic tasting, there are electronic sensors that work just like the taste buds on your tongue, measuring the quantity of various taste-giving compounds, acidity, etc. While these electronic sensors can't actually tell you how something tastes — that's a very subjective, human thing — they are very good at comparing two foods scientifically. Meanwhile at a tiny food stall along one of Bangkok's traffic-clogged boulevards, Thaweekiat Nimmalairatana, questioned the necessity of a robatic taster. "I use my tongue to test if it's delicious or not," said Nimmalairatana. "I think the government should consider using a human to gauge authenticity."

Comment: Re:There Ain't No Stealth In Space (Score 1) 427

by khasim (#48021233) Attached to: The Physics of Space Battles

Do you need me to post the distances that you did not understand?

kilometers 350,000 is about Earth to the Moon
kilometers 200,000,000 is about Earth to Mars
kilometers 39,900,000,000,000 is about Earth to Alpha Centauri

Light travels about 1,000,000 kilometers an hour.

So what you're saying is that from a million plus kilometers away, a ship with a forward profile of maybe a few score meters ...

That is just 3x the distance from the Earth to the Moon.

And only 1/200th of the distance from the Earth to Mars.

And that isn't even counting the kilometers of shielding that you kept insisting upon.

area of a circle = pi r r
So a circle with a radius of 2 kilometers (you've proposed larger shielding) would give an area of 12,566,400 square meters. Which should be very easy to spot at 1,000,000 kilometers.

It's the laws of physics. And the math isn't that difficult, either.

Comment: Re:I don't like it. (Score 1) 122

deviating from the formula is almost always a way to make a crappy book

Go grab the last 20 titles in any genre. You'll see that most of them adhere to the tropes of that genre and are still crap.

A good author can write a good story even with the most formulaic plot.

A good author can write a good story even while subverting the established tropes of the genre.

But that's not important in this specific case. Martin can still change the specific tropes for individual characters in order to "twist" the ending from the predictions. (Boy meets/loses/gets girl) becomes (boy meets/loses/dies-in-battle-to-impress girl who married the local royalty once boy had left).

Since the "mathematical model" was wrong there, who's to say it isn't also wrong in X?

Comment: I don't like it. (Score 1) 122

Nevertheless, this statistical approach to literature could introduce the process of mathematical modelling to more people than any textbook.

Until the writer reads that analysis and intentionally deviates from it.

In which case you've just shown them that mathematical modelling is unreliable.

When the real lesson should be not to use a tool for a job for which it was never intended.

Comment: Re:There Ain't No Stealth In Space (Score 1) 427

by khasim (#48020755) Attached to: The Physics of Space Battles

You just quoted my explanation "rapid expansion of the propellant in a vacuum in addition to the above mentioned thermal radiation".

I quoted you to point out that your explanation was not an explanation. Explain how the exhaust will cool to background radiation levels.

I didn't bring up Voyager, that was brought up by the article on the impossibility of stealth in space.

I'll quote you, again:

Similarly, the two Voyager spacecraft have easily detectable signals because those signals are directed by a high gain parabolic antenna at Earth, because the signal has a narrow bandwidth, and because there's a huge dish at Earth to pick up the signal.

That is what you posted. And they will take 300 years to reach the Oort cloud.

You first have to show that.

Easy. I'll use the analogy of Harry Potter and the Cloak of Claimed Invisibility.

You claim that a cloak of invisibility is possible.

I say that physics says it is not.

You say that it is possible ... as long as you use tactics to take out anyone who isn't blind.

I say that if it was an invisibility cloak you wouldn't need tactics to take out anyone who isn't blind. The cloak would make you invisible. They would not see you. Tactics do not beat physics.

But you keep insisting that the cloak makes you invisible ... as long as there isn't anyone who can see you.

Comment: Re:There Ain't No Stealth In Space (Score 1) 427

by khasim (#48018201) Attached to: The Physics of Space Battles

Except it won't be glowing.

Tell me more about how it is going to cool off to background radiation levels.

Unlike the spacecraft itself, rocket exhaust (chemical or otherwise) will cool rapidly to the microwave background temperature (rapid expansion of the propellant in a vacuum in addition to the above mentioned thermal radiation).

You are claiming that. But you have not explained how it would happen.

Sure, all of this can be detected by a large enough and sophisticated enough detector.

And you've just contradicted yourself.

If the exhaust has cooled to background radiation levels then it would blend in with the background radiation. It would not be detectable. No matter how "large enough and sophisticated enough detector" there was.

To claim that physics prevents stealth is to ignore the actual physics as well as tactical considerations like the size and mass of a viable detector.

And you've just contradicted yourself in that single sentence.

Tactics do not beat physics. So there is no "as well as". You've claimed that the exhaust would be as cold as the background of space while still driving a ship fast enough to cover distance X in time Y.

Not unless X is approaching 0 or Y is approaching infinity.

Like your previous example of Voyager. Which you did not like once I pointed out that it would take 300 years just to reach the Oort cloud.

Comment: Re:There Ain't No Stealth In Space (Score 1) 427

by khasim (#48018155) Attached to: The Physics of Space Battles

There was no "them", only one point.

And you keep complaining that I addressed them. It was your post. If you did not like it then you should not have posted it.

This is remarkable. You were the one who started banging on about interstellar distances (and then interplanetary for some mysterious reason), not me.

Because distance is the point.

You do not understand that. But I will explain it again.

kilometers 350,000 is about Earth to the Moon
kilometers 200,000,000 is about Earth to Mars
kilometers 39,900,000,000,000 is about Earth to Alpha Centauri

Light travels about 1,000,000 kilometers an hour.

So the exhaust from your example ship will, eventually, disperse beyond your example shield. When that happens, the radiation given off by it will travel at about 1,000,000 kilometers an hour. That means that the math for determining when the enemy will see your ship's silhouette is very simple.

Not in the least, I'm arguing that the heat from the exhaust would have reached negligible levels by the time whatever miniscule amount of it got around the shield, mostly due to the vast majority of it being blocked by the ship and being blasted directly backwards.

I've already given you an example of a laser from Earth to the Moon. Here it is again.
"At the Moon's surface, the beam is about 6.5 kilometers (four miles) wide ..."
https://en.wikipedia.org/wiki/...
So you are claiming that the exhaust from your example ship is MORE tightly focused than a laser is.

The laws of physics disagree with that.

And as another poster pointed out to you, the exhaust isn't nearly as hot as some might imagine.

You don't know how hot I "imagine" it to be. All it has to be is hot enough to be detected. And since the instruments today can (probably) detect leftover radiation from The Big Bang it looks like the laws of physics contradict you again.

And yet again nobody is talking about going from Earth to Mars except yourself.

That is the distance that you quoted. Whether you understood what that meant in actual terms when you quoted it I'm sure that it sounded good to you when you posted it.

What you posted was:

So what you're saying is that from a million plus kilometers away, a ship with a forward profile of maybe a few score meters ...

Now "a million plus kilometers" might sound impressive to someone who does not understand the actual distances in space. But that is just 3x the distance from the Earth to the Moon.

And 1/200th of the distance from the Earth to Mars.

So, yes, detecting an object at that range is easy.

And yet again nobody is talking about going from Earth to Mars except yourself.

I'm pointing out that you do not know what the distances you are quoting mean in the real world.

It the laws of physics.

Comment: Re:I dunno about LEDs, but CFLs don't last (Score 1) 594

by Rei (#48016707) Attached to: The Great Lightbulb Conspiracy

The EPA guidelines are in line with the level of risk: very, very little. If you want to cut your mercury exposure, don't stop using CFLs, stop eating seafood.

As for the Bridges case, you should read the Maine EPA's account. CFLs were new back then, and they had decided to use her case to learn more about what sort of advice they should give for dealing with broken bulbs. So they sent someone with a meter because they wanted to learn more, not because that's standard practice. The carpet was already intended for removal as part of a rennovation. They took readings all over the room. The only place with "high" levels was right where the bulb broke - not in the ambient air, not anywhere else on the carpet, not on the toys, not even under the carpet where it broke. I say "high" because even the levels right where it broke weren't actually high, just over Maine's long-term exposure guidelines (which is obviously not applicable to a temporary event). Moving the meter even six to eight inches away rom the breakage point dropped the levels way down. She was told that the bulb breakage was "of negligible health concern". However "the homeowner expressed particular nervousness about exposures to mercury even in low numbers", so they told her what she could do if it bothered her, one of which was calling a cleanup contractor. And of course any private cleanup contractor will charge you an utter fortune. The Maine EPA came back two days later after the story hit the news, before anything had been done in the house. The area where the bulb broke had dropped down below Maine's limit.

The case was ridiculously blown out of proportion.

Comment: Re:There Ain't No Stealth In Space (Score 1) 427

by khasim (#48016359) Attached to: The Physics of Space Battles

Who said I disagreed with them?

You are the one who keeps complaining about me addressing them. If you disagree with them then you should not have posted them.

Not that readers need it pointed out, but Mars has mysteriously entered the discussion.

There is no "mysteriously" about it. The distance you started quoting is less than the distance from the Earth to Mars.

In other words, interplanetary.

Interplanetary != Interstellar

Argh. You're comparing an exhaust, which rapidly cools off in space and generally acts very differently to a laser, to a laser.

No. I'm comparing the dispersal. You are arguing that the exhaust would not disperse.

In other words, you are arguing that the exhaust is focused BETTER than a laser.

And the heat has to go somewhere. It's one of the laws of physics.

You keep using that word. It does not mean what you think it means.

Yes it does. The heat of the exhaust does not vanish. Reaction mass does not vanish. Ships need a force to move them.

Physics.

I seriously have no idea where you're getting this stuff.

That you do not understand the distances involved.

In order for the ship to be hidden, it cannot be silhouetted against its own exhaust. Which means that the exhaust cannot cross the edge of the shield before it has cooled to background radiation. But the ship has to travel (at best) 100's of millions of kilometers (Earth to Mars) while the exhaust only has to travel 10 kilometers (at most) laterally before cooling.

In other words, your example ship would be a dark, shielded spot in the middle of a glowing cloud of its own exhaust. It would look like a bullseye.

It's the laws of physics.

Comment: Re:There Ain't No Stealth In Space (Score 1) 427

by khasim (#48016295) Attached to: The Physics of Space Battles

If you're going to bring that up, please remember that the above observation is completely irrelevant ...

You were the one who brought up the Voyager craft as an example.

If you want to make the ships that difficult to detect then you are going to be travelling that slow. 300 years to reach the Oort cloud. It's the laws of physics.

"Probably very hot" is considerable fail right there.

In your opinion. The point being that it is hot enough to be detected. Now you can argue whether it is or is not but I'd once again refer you to physics.

Further, the "shielding" that everyone talks about just isn't that heavy.

So far I haven't seen anyone posting what that "shielding" is made of.

But it does not matter except that more shielding requires bigger engines.

The reason it does not matter is that the exhaust will, eventually, travel further to the side than the shielding can shield. Then it will be seen as a glowing cloud behind the shielded ship.

The whole concept of shielding for stealth revolves around the exhaust NOT being able to travel X distance to the side before cooling to background temps BEFORE the ship travels Y distance forward.

Given that X is usually measured in, at most, 10's of kilometers while Y is measured in THOUSANDS OF MILLIONS of kilometers I think that the math should be self explanatory.

But, just in case, it means that the exhaust would have to travel laterally at a rate that is less than 1/100,000,000,000 the speed of the ship.

The only difference between a car salesman and a computer salesman is that the car salesman knows he's lying.

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