Domain: physicscentral.com
Stories and comments across the archive that link to physicscentral.com.
Comments · 31
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More information
Here are some links to more information on atomic clocks, their development, and why they're needed:
How and why atomic clocks were invented
How atomic clock accuracy was greatly increased
How atomic clocks work
Animations showing how atomic clocks work
Why atomic clocks are needed for GPS
Video showing how atomic clocks are used for GPS -
Re:Bill would agree.
Also, deflategate, he got the ideal gas law all wrong, and made an ass out of himself claiming that the ball couldn't have lost pressure.
http://physicsbuzz.physicscent... http://www.digitaltrends.com/h...
Yeah, so?
Hawking has made mistakes http://www.independent.co.uk/news/science/stephen-hawking-admits-the-biggest-blunder-of-his-scientific-career-early-belief-that-everything-8568418.html,
Einstein has too http://discovermagazine.com/2008/sep/01-einsteins-23-biggest-mistakes,
and so has Newton.Most famous scientists have till their death defended a claim that was shown wrong long before.
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Re:Bill would agree.
Also, deflategate, he got the ideal gas law all wrong, and made an ass out of himself claiming that the ball couldn't have lost pressure.
http://physicsbuzz.physicscent...
http://www.digitaltrends.com/h... -
Re:Break the rules to keep traffic flowing
There was a study a few years ago about traffic in cities. They found that if all the drivers kept to rules that most cities would halt into complete grid lock.
People need to break rules to clear junctions, to pass cars that are stuck, and even force priority to not starve lanes going into a junction.I travel by bus to and from work in Amsterdam, it is quite a long trip which includes traffic jams in the inner city. The bus driver needs to often break the rules to be able to pass cars, and force priority on junction because they are often stuck. Cars are backing up, cars are trying to make room.
That is kinda BS.
This is the popular press articles about the study:
http://abcnews.go.com/Technolo...
http://physicsbuzz.physicscent...Here is the actual study. http://arxiv.org/abs/0901.3513
Basically they designed a automata simulation that would have gridlock, and made a rule that would avoid jams forming, but called that rule "rule-breaking"; probably because if you did that in a car you would die in a head-on collision.Abstract:
A system of agents moving along a road in both directions is studied numerically within a cellular-automata formulation. An agent steps to the right with probability q or to the left with 1q when encountering other agents. Our model is restricted to two agent types, traffic-rule abiders (q=1) and traffic-rule ignorers (q=1/2). The traffic flow, resulting from the interaction between these two types of agents, is obtained as a function of density and relative fraction. The risk for jamming at a fixed density, when starting from a disordered situation, is smaller when every agent abides by a traffic rule than when all agents ignore the rule. Nevertheless, the absolute minimum occurs when a small fraction of ignorers are present within a majority of abiders. The characteristic features for the spatial structure of the flow pattern are obtained and discussed.
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..and so?
I'm just not sure why we should care. There are no known non-thermal effects of microwaves, and the thermal energy of a cell phone just isn't enough to pay attention to-- three watts, when it's transmitting at full power.
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Re:Mass production ?
Somebody with a Nobel Prize would disagree with you.
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Re:Energy-matter synthesis
We don't have to, smartass. We've had slow light for quite awhile now. My link even says we've slowed it down to about 1mph.
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Re: frosty piss
I remember a study not long ago that compared the smoothness of traffic in different simulated scenarios. The worst was when nobody followed the rules, that resulted in total choas and mayhem. A much better scenario was when everybody followed the rules. But somewhat suprisingly, the best results were achieved when most people followed the rules but a significant fraction did not! The rule breakers helped fill in gaps and actually caused traffic to flow more smoothly.
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Old news?
There was an article from 2010 that talked about the theoretical limit to laser beam energy. From the article:
"At high laser intensities interaction of the created electron and positron with the laser field can lead to production of multiple new particles and thus to formation of an avalanche-like electromagnetic cascade"
Here's the link to the article in question: http://physicsbuzz.physicscent...
That article was ultimately using this article as a source. -
Panic? Misleading title
This isn't panic. It's more of a "Houston, we have a problem" sort of situation. You've got a problem, you deal with it. "Panic" means people going "AAAAAAAAAHH!" After screaming for a year and a half, they must be getting pretty hoarse. On the other hand, the must have been screaming "AAAAH" for just about long enough to warm up a cup of coffee. So my advice would be, by now, Keep calm and have a cuppa.
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I visited the National Ignition Facility this year
...and it's one of the most impressive scientific endeavors we've undertaken.
Yes, one of it's missions is "stockpile stewardship" -- maintaining the integrity of the United States nuclear stockpile without nuclear testing, via simulations and tests.
But it also has a goal of initiating "ignition": a sustained ("sustained" being relative, here) fusion reaction which produces more power than was put in.
Even if there is no immediate practical application, understanding various aspects of fusion, and the science it takes to get there, is critical to our energy future.
In short, like many military and national security projects, this is a truly dual-use.
The NIF just made history by firing its 192 beams to deliver more than 500 terawatts and 1.85 megajoules of energy to its target -- more than 1000 times the power the United States uses at any particular instant, and more than 100 times the power of any other laser.
We do need science like NIF, and I'm still pained by the US decision to kill the Superconducting Super Collider (SSC), what was to be the most powerful particle accelerator in the world -- significantly more so than the LHC -- after 14 miles of tunnels were dug and over $2 billion spent.
I hope this article wasn't unintentionally accurate when it called the SSC the "high water mark of American science"...(must see photos by the way).
We NEED big science.
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This isn't a good idea for one reason, IMO
FTA - "Google's car adheres strictly to the speed limit and follows the rules of the road, says Tom Jacobs, a spokesman for the Nevada Department of Motor Vehicles...".. and from the summary... "They would mean fewer traffic jams. 'Congestion would be something you could tell your grandchildren about, once upon a time.'"
Wrong. I know it's counter-intuitive to those who believe strict adherence to current traffic laws is the best way, but according to a study of traffic flow done in 2009, traffic flow actually IMPROVES when some drivers break the laws. The ideal percentage of law-breaking drivers (the speeders, the "jerks who cut you off" and fill in that space in front of you, etc.) was discovered to be about 40%. Above or below that threshold made traffic worse...
So, this means that if cars were actually forced to follow ALL traffic laws to the letter, as this Google system would, traffic would actually get quite a bit worse for everyone, not better, as the summary above incorrectly suggests.
Of course, automated cars COULD over time force some fearmonger-driven (or revenue-driven) draconian traffic laws to be updated or repealed due to automated technology. That's assuming that the government officials could be as cold and logical as the automated cars and their algorithms, however, and that's probably not going to be happening - at least not until Skynet takes over...
BTW - I want no part of a car-tracking system like this. Even if it was designed to be anonymous from the start, certain government officials would sooner or later find a reason to override the anonymity. Maybe it'd be under the auspices of a "per mile tax", "disease/pest vector tracking" "terrorist monitoring", etc., but they'd find an innocuous or necessary enough of a reason to convince 50.1% of us that anonymity is "bad", and it'd all be over.
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Lasers = Awesome
Spectra the Original Laser Superhero! http://www.physicscentral.com/experiment/physicsquest/past/pq09.cfm
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What is a Higgs Bosom worth?
http://www.physicscentral.com/buzz/blog/index.cfm?postid=2156439899482364662
And the better answer is:
The sum total of what it cost to find one. -
Dance of the Knits
How about some knitting to go with your tea?
http://www.physicscentral.com/explore/sots/episode1.cfm
Pretty cool!
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Re:100% reliability not needed
I think this might be what you were looking for:
http://www.autoblog.com/2009/08/01/driving-like-a-jerk-reportedly-helps-reduce-traffic-jams/Which refers to:
http://physicsbuzz.physicscentral.com/2009/07/jerks-actually-reduce-risk-of-traffic.html -
Re:This is why we can't have nice things
fAny advanced technology appears as magic to a suficiently primitive culture Unicorns are real: http://2.bp.blogspot.com/_49Bcbuc6ngM/S-bkerpX2uI/AAAAAAAAA5k/RYeAmEeP_L8/s1600/Narwhal+8.jpg Not sure about voodoo. LOL http://physicsbuzz.physicscentral.com/2010/09/experiment-to-test-string-theory.html String theory is now and will become increasingly testable. Deepak chokra is an idiot that has nothing to do with theoretical physics. There may be just one electron: http://en.wikipedia.org/wiki/One-electron_universe Richard feynman who postulated the one electron theory won a nobel peace prize in physics. What credential do you have to mock him with your "one atom" rant?
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Re:matter from light?
Creating light from matter is rather ordinary in terms of physics, as can be seen in nuclear explosions. But the SLAC experiment was the first to produce the opposite, and while the effect had been expected for some 50 years, the equipment hadn't existed to test it experimentally. It is known amongst physicists as creating "spark in a vacuum." When the electromagnetic field has enough energy, light becomes matter as a positron-electron pair is produced.
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Re:Sounds like california
See: http://www.physicscentral.com/buzz/blog/index.cfm?postid=3414795237807494042
I think that's just based on a model. But I won't be surprised if it's also true in practice.
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Re:Useless in the city
Studies disagree with your oft repeated knee jerk assumptions:
http://www.physicscentral.com/buzz/blog/index.cfm?postid=3414795237807494042
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traffic = crowds?
I would imagine the same principle might apply to those who in crowds who rush inbetween people or push past others.
While similar i'm not sure it fits 'the mob as a fluid' theory though:
http://physicsbuzz.physicscentral.com/2009/01/physics-of-crowds.html
Itself somewhat dismissed (at least in passing) for disregarding irrationality here:
http://www.economist.com/sciencetechnology/tq/displayStory.cfm?story_id=13174313
In all probability it may be that a cross of all factors is at work. Perhaps some people see it as queuing while others always look for the alternative way through. -
Re:Summary of Kurzweil's "ideas"
When I said 'daguerreotypical' I was making an adjective out of daguerreotype, the first common method of photography. If you told Louis Daguerre in 1839 that in little more than a century we'd be taking pictures of astronomical events that span back through 95% of the time this universe has existed, physical waveforms travelling a mere three thousandths of a percent slower than light itself, and constructing cameras with lasers (not that he would understand those) that would take 6.1 million pictures/second. (Not to mention atomic force microscopes imaging atomic structures.)
I'm sure that faced with all that, Louis Daguerre would be agape. Seminal technologies are fantastically underwhelming compared to refinements (Exhibit A vs. modern computers). I would say that given current technological trends in neurological imaging and analysis, the mere idea of mapping and copying is conservative. Most likely there are even more advanced applications that haven't even been conceived that will rear their heads in a century or two. -
Speed of Light is NOT constant
Lene Hau, a Harvard Uni physicist, has slowed light (even stopped it) in recent experiments.
See http://www.physicscentral.com/people/2002/hau.html
If light can be slowed its speed is not constant... who's to say in another decade faster than 3E8 ms-1 isn't the upper limit. Not to mention worm holes etc. In evaluating all theories you should remember our humble beginnings. There is more to come.
Never say never. -
Re:Facts
Not true. The speed of light is a constant, even near a black hole.
So how come Lene Hau claims to be able to reduce the speed of light? -
Re:Now that is an interesting proposition
It's not just that. If you look at heart rate versus life span you find that the number of heart beats in a lifespan for different species is a constant (so think of it as related to the metabolic time). A physicist named Geoffrey West is the one who worked that (and a bunch of other scaling laws) out:
http://www.physicscentral.com/action/action-03-01. html -
Re:Broil?
Both standard ovens and fan ovens are convection ovens.
Are you sure?Although both of these ovens use convection to carry heat, only one of them has the word "convection" in its name. The difference between them is that while a standard oven waits for natural convection to move heat slowly from the heat source to the food, a convection oven uses a fan to drive heat rapidly from source to food. -- Physics central
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Re:X2 a Reality
I'm sure another filter could be used before the magnet to ensure that only their particles are pulled out. This shows that a red blood cell is 10um(10^-6), while the particle size is somewhere between 100 and 5000 nm(10^-9m), or
.1 to 5um.
The article mentioned not being too worried about getting 100% of the particles out anyway, so I think there is some wiggle room with another filter. -
Re:The Standard Model
The standard model is pretty well fucked anyway. It's not a revolution, it's a kick in the ass that's going to force us to re-examine a large amount of our basic assumptions/research done in the Standard Model.
Already outstanding issues include pentaquarks (5-quark exotic baryons), the inability to find the Higgs boson (not so much finding it, but having the found mass be correct), muon g-factor anomalies, and kaon decay, to name but a few.
I guess what I'm saying is: it's going to be a long time. Don't hold your breath. -
Practical, useful, feasible...
and very timely:
Getting power from the moon.
More details at Space.com. -
Just deliver on the promises!
Do you remember when Enterprise was first introduced? We were promised it would be "Star Trek with phasers". In other words, lots of action, less "character development" episodes and other slow topics.
That recent "Stigma" episode (T'Pol has mind-meld disease) was as far from "Star Trek with phasers" as you can get. On the other hand, that recent "Canamar" epsiode (Con Air, in space) was pretty cool.
Here is the best hope for the series: Berman and Pillar have stopped writing all the episodes. Every time I watch Enterprise, I make careful note of who wrote the episode. The whole first season was purely written by Berman and Pillar. Recently, we have had a string of episodes written by other writers.
If they want to make us happy, they ought to get some scripts from actual SF authors. How about John E. Stith, David Weber, or Catherine Asaro? (I draw the line at Piers Anthony, though...)
steveha -
Re:what about the velocity?
It's even more complicated than this. There are two kinds of mass people talk about in connection with neutrinos: Dirac mass and Majorana mass. Dirac mass is the same kind of thing as the conventional rest mass of other particles. Majorana mass is tied together with the helicity of the particle: left handed neutrinos and right handed antineutrinos are one and the same, more or less.
All this is off the top of my head, I'm no longer in the business nowadays.
For further reference, here's an article at physicscentral.com relating to the experiment. It does not give much more details on the technical aspects of the mass, though. And here's the SNO press release off of their homepage.