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By Tushna Comissariat
Would you know exactly where to run and shelter in the event of nuclear fallout in your city? Would it be best to stay where you are or move, and for how long should you stay inside before venturing out into your post-apocalyptic world? If these questions have plagued your mind, you can now turn to a new model developed by Michael Dillon, an atmospheric scientist at the Lawrence Livermore National Laboratory in California, US. Dillon’s practical model outlines simple ideas and suggestions that the average person – without advanced equipment and know-how – could apply in the event of a low-level nuclear attack, which is the most plausible type likely to take place in today’s political climate. You can read all about about the model on both the io9 website and in Science magazine, and then map out your perfect route.
Here’s a little experiment for you to try: get a long chain of small metal beads, put them into a tall jar or glass, then grab the end of the string and slowly pull it out of the jar and let it drop to the floor. Then sit back and watch in amazement as the chain apparently defies gravity and rises up before falling to the ground. The experiment has left people all over the world flummoxed, but now physicist John Biggins of the University of Cambridge in the UK has an answer. You can read about what he has to say on the Nature website and watch his explanatory video above.
“What scientific idea is ready for retirement?” is the question that Edge.org – the online platform of a society of intellectuals that first met in 1981 – is asking this year. The website itself was launched in 1996 and is an archive of essays written by the aforementioned intellectuals – a mix of scientists, artists, philosophers, technologists and entrepreneurs – based on the annual questions. While there are plenty of physics-related answers in the 174 responses to this year’s question, we were amused to note that nine separate physicists wrote about or mentioned string theory in their feedback. I will leave you to find out for yourselves whether they were for or against it. For a selection of responses, take a look at this article in the Observer.
I will leave you with what is undoubtedly the most amusing physics-related story of the week. A student called Sairam Gudiseva “Rickrolled” his physics professor by surreptitiously and tediously inserting every word of the chorus of Rick Astley’s famed song “Never gonna give you up” into an essay about Neils Bohr. For those of you who have had the good fortune to never have been rickrolled yourselves, the rather informative Wikipedia entry explains the popular Iinternet meme and more here!
This is amazing. Great job guys, would never of have thought of that. =) It’s amazing how things work in this crazy world. =)
Hello Sir,
Regarding to the chain fountain: The demonstration was fantastic. Below is my understanding on how it happens:
1) Someone pulls the bead chain off the box, lets say towards right vector.
2) Immediately gravity comes into picture and the chain starts falling down.
3) When the chain is falling, gravity is one force that is acting downwards and as part of gravity there is one more force which points right off the box.
4) This X force makes each bead to get on top of the other, but before the bead reaches on top of the other, the below bead is already being pulled down by gravity.
So this is basically what i see “Bead climbing and falling phenomenon”.
For the chain fountain in the field of gravity, it is true that the chain has to consist of linked rods to undergo rotation, when pulled up at one edge and down from its pot by gravity, to produce the reactive force(the fountain force!) at the other end. If the rods are replaced by sphercal beads, due to their spherical symmetry, there will not be any reactive force to produce this fountain. Hence, the “rodiness” of the chain elements and not the length of the flexible links, is essential for this beautiful phenomenon.
I am not so sure about the explaination.
My initial hypothesis, which I think is still to be proved wrong, is that the “push” comes more from the rods next to the “climbing one” than from the shape of a particular one.
I think the initial pull moves many rods in the recipient and if they are close, their interaction transfers more impulse to the one “about to climb”.
In fact I had made some simulations with billard balls colliding, some time ago, and when they are close enough, they have very interesting behaviours.
You made an experiment with close maccaroni, and separate balls.
What about close balls and separate maccaroni?
My hypothesis then, would be closer to “wave mechanics” on its discrete limit.
(sorry about my English […and italian], not a native speaker)
P.S.: That would be coherent with the behaviour of maccaroni. Only in the end of the chain the fountain is formed, that is because their shape is preventing the effect because they are too big for the recipient (the wave can’t be formed because of the indirect interactions with the walls), until there is only a few of them. If there were little balls that wouldn’t happen (but they have to be very close).
PS2: Of course if they are too close for their size it won’t happen either, or won’t be noticeable (that’s before anyone makes a “too close” experiment). The case of a thin rope can show that.
It could be nice to determine the relationship between ball size (and/or mass) and distance between balls (if the hypothesis is correct).
If the hypothesis is correct it would be a nice way to show how similar “configurations” can arise different behaviours when they became “discrete” instead of “continous”.
Could the shape of the fountain be related to the wavelength of a stationary wave formed in the chain? (would be nice
)
I thought the Edge responses were interesting, particularly Max Tegmark’s. He “retired” infinity. Now take a look at his level-1 multiverse:
“A generic prediction of chaotic inflation is an infinite ergodic universe, which, being infinite, must contain Hubble volumes realizing all initial conditions. Accordingly, an infinite universe will contain an infinite number of Hubble volumes…”
He’s retired his level-1 multiverse too. Oops!