After discussing the Artic’s missing ice (don’t worry, it is not missing - there is more ice there this year then the last year), NYT pointed out two more things that we can scratch off from the worry list:
9. The universe’s missing mass. Even if the fate of the universe — steady expansion or cataclysmic collapse — depends on the amount of dark matter that is out there somewhere, you can rest assured that no one blames you for losing it. And most experts doubt this collapse will occur during your vacation.
10. Unmarked wormholes. Could your vacation be interrupted by a sudden plunge into a wormhole? From my limited analysis of space-time theory and the movie “Jumper,” I would have to say that the possibility cannot be eliminated. I would also concede that if the wormhole led to an alternate universe, there’s a good chance your luggage would be lost in transit.
I wished they had included the worry about blackholes from LHC - yes, you can scratch that off your worry list too.
I thought it might be interesting to start gathering up the Physics related Facebook Status Messages that I have been posting on my Facebook account.
Here are some of my favorites.
Sunny feels the chill from the the LHC (Large Hadron Collider) being cooled to 1.9 Kelvin (-271C; -456F) - colder than deep space. Where did I put my space heater?
Sunny feels like he’s diagonally parked in a parallel universe.
Sunny exists purely as a probability density function; he can be at more than one places at the same time.
Basic research is what I am doing when I don’t know what I am doing.
Sunny is still searching for Higgs.
I abhor M theory with every fiber of my being.
almost finished with the paper, I just has to dot my “i” and cross my “h”.
Sunny has learned not to store plutonium in a tupperwear container.
is pondering, if Schroedinger’s Cat walks into a forest, and no one is around to observe it, is he really in the forest?
Wanted, dead AND alive, Schrödinger’s Cat.
Hopefully we will have plenty more by the time the next Talk Like A Physicist Day comes along (March 14, 2009).
So simple to set up; a metal sheet on top of a booming subwoofer and pour some non-newtonian fluid (cornstarch and water) on it and watch a new type of universe emerge right in front of your eyes!
What is a non-newtonian fluid?
A non-Newtonian fluid is a fluid whose viscosity is variable based on applied stress. The most commonly known non-Newtonian fluid is cornstarch dissolved in water. Contrast with Newtonian fluids like water, whose behavior can be described exclusively by temperature and pressure, not the forces acting on it from second to second. Non-Newtonian fluids are fascinating substances that can be used to help us understand physics in more detail, in an exciting, hands-on way.
If you punch a bucket full of non-Newtonian fluid, the stress introduced by the incoming force causes the atoms in the fluid to rearrange such that it behaves like a solid. Your hand will not go through. However, if you shove your hand into the fluid slowly, it will penetrate successfully. If you pull your hand out abruptly, it will again behave like a solid, and you can literally pull a bucket of the fluid out of its container in this way. However, the effect doesn’t last for long - if stress is not continuously applied, the non-Newtonian fluid turns back into a liquid, and will ooze right off your hand.
Here is another video of large pool of cornstarch+water!
One of the best suggestion that I have heard recently is to make the speed bumps out of non-newtonian fluids, so if you are moving slowly, you will go through them but if you are moving too fast, it will act as a real speed bump.
His blog It’s the Rheo Thing has a nice tag line “Everything flows, but only the macromolecules are worth the time.”
Non-Newtonian fluids can be fit into at least 4 categories, of which the cornstarch/water mixture you describe is only 1: rheopexy. This is where the viscosity of the fluid increases over time while a constant shear rate is applied. This is often confused with dilatancy (shear thickening), where the viscosity increases as the shear rate increase. The opposite behaviors are also possible. Shear thinning is very common with molten plastics - the viscosity decreases as the shear rate increases, and thixotopric fluids will show a decrease in viscosity over time at a constant shear rate.
Beyond those four categories, there are also Bingham plastics which do not flow until a critical stress is exceeded and Boger fluids which show elasticity but a Newtonian viscosity.
So you can see that some of your statements above are not exactly correct - they are overly broad.
Lastly, I would submit that a cornstarch/water is NOT the most common non-Newtonian fluid as it takes a fairly large amount of cornstarch to acheive the effect (~ 6:5 cornstarch:water on a weight basis IIRC). Considering that polyethylene is the largest volume plastic and it is shear-thinning in the molten state, I would submit that material for the title of most-common non-Newtonian fluid. But if you are looking for “everyday” materials found around the house, there are other more popular examples than cornstarch in water. Paint, tomato juice, peanut butter, toothpaste, …
This beautiful program raytraces through a three-dimensional cloud density that represents the wavefunction’s probability density and presents its results in real-time (up to 48 frames per second on the latest hardware). The user interface is very interactive and provides a wide degree of flexibility.
It contains all 140 eigenstates up to the n=7 energy level and the allowed spectral transitions between those eigenstates. It also allows a state formed by a superposition (see below) of up to eight of those eigenstates allowing for over 3 trillion possible states. The program can display a wavefunction as a picture of a cloud, use color as phase, plot in red-cyan left/right for 3D glasses, and slice the wavefunction.
Dauger’s program (called Atom in a Box) lets you not only talk (like a physicist) but lets you make your own home movies of quantum wavefunctions, probably the closest humans will get in my lifetime to visualizing “what atoms really look like”. Sophisticated enough to satisfy a real physicist yet easy enough for a normal person to use to toy with the structure of the universe at a very basic level. It’s a great way to learn about quantum mechanics.
We are able to view all entities, from the microworld to the universe, from a single perspective. By setting them up against a scale, we are able to compare and understand things which cannot be physically compared.
Today, using the electron microscope and astronomical telescope, we can see the objects which we have not been aware of its existence before. Are you able to fathom, or even roughly grasp, these sizes?
See our Universcale and experience the sizes of various objects.
This is a remarkably beautiful interactive website that takes you from the nano meter sized structure to something as big as the size of the universe.
The part that I really like about this demo is that there is no sudden and unexplained transition from using the scale of meters or kilometers in describing things around us to something that is described in light years when we shift to explaining the cosmos.
To understand a distance of “a light year”, the reader has to know and appreciate the speed of the light (most can’t fathom it), he/she has to have the imagination to figure out how much does light travel in a year (most people can’t even tell you how many seconds there are in a year); and then has to transpose its natural instinct of using “year” to describe time to using a light year to describe distance. I think that is asking for way too much from an uninitiated user.
A light year is about 10 trillion kilometers. So the factor of 10^16 remains unappreciated and misunderstood.
But I digress; the Universcale is an interesting way to grapple with the scales of things around you, starting from atoms to the far away galaxies that you see. Check it out.
Size matters, or so this website will have it. This amazing site shows you scale as you have probably never seen it - from the smallest speck to the largest asteroid and beyond. Fantastic graphics will give you a real idea of your place on the planet - or indeed the universe.
Suggestion+contributions
Please contact sunny at talklikeaphysicist dot com
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