Group items tagged

'Oxford philosopher Nick Bostrom has argued that we are more likely to be in such a simulation than not,' writes Frenkel. 'If such simulations are possible in theory, he reasons, then eventually humans will create them - presumably many of them. If this is so, in time there will be many more simulated worlds than nonsimulated ones. Statistically speaking, therefore, we are more likely to be living in a simulated world than the real one.'... right...

Players with access to quantum resources can outperform classical ones. This will lead to novel joint strategies, impossible to achieve classically. Moreover, some of these strategies represent equilibrium points, leading to the notion of quantum/no-signalling Nash equilibrium.

What is the best (wisest) size for a group of individuals? Couzin and Kao put together a series of mathematical models that included correlation and several cues. In one model, for example, a group of animals had to choose between two options-think of two places to find food. But the cues for each choice were not equally reliable, nor were they equally correlated. The scientists found that in these models, a group was more likely to choose the superior option than an individual. Common experience will make us expect that the bigger the group got, the wiser it would become. But they found something very different. Small groups did better than individuals. But bigger groups did not do better than small groups. In fact, they did worse. A group of 5 to 20 individuals made better decisions than an infinitely large crowd. The problem with big groups is this: a faction of the group will follow correlated cues-in other words, the cues that look the same to many individuals. If a correlated cue is misleading, it may cause the whole faction to cast the wrong vote. Couzin and Kao found that this faction can drown out the diversity of information coming from the uncorrelated cue. And this problem only gets worse as the group gets bigger.

Couzin research was the starting point that co-inspired PaGMO from the very beginning. We invited him (and he came) at a formation flying conference for a plenary here in ESTEC. You can see PaGMO as a collective problem solving simulation. In that respect, we learned already that the size of the group and its internal structure (topology) counts and cannot be too large or too random. One of the project the ACT is running (and currently seeking for new ideas/actors) is briefly described here (http://esa.github.io/pygmo/examples/example2.html) and attempts answering the question :"How is collective decision making influenced by the information flow through the group?" by looking at complex simulations of large 'archipelagos'.

I am also looking into this idea since some time and it seems NASA is already ahead, awarding two contract to investigate magnetoshell aerocapture. This could be interesting for probes that want to enter eg Marsian atmospheres at relatively high velocity. Or for multiple re-entry s/c at Earth. The idea of the experiment, The satellite will carry a copper coil, powered by a lithium-ion battery, that generates a magnetic field around the probe. As it descends, the spacecraft will eject a small amount of plasma. This gets trapped in the magnetic field, creating a protective bubble that stops air molecules colliding with the craft and producing heat.

A few years back Mimmo has worked on this, rather from the theory side if I remember well ...

The power requirements for such a thing must be HUGE!

tesla announcing home batteries at 350$/kW

Let's do some simple maths... Here in UK, example "economy 7" tarif yields night kWh approx. 12 pence cheaper than during day. Let's say the goal is to store energy equivalent to running a 2kW storage heater for 6 hours during the day. We need 12 kWh, so 12 times $350 this means need to spend approx. 1920 pounds for batteries. Time to break even at ROI: 1920 / 0.12 ~ 7.3 years... And this is assuming using the heater 365 days a year, and quite an expensive tariff (prepaid). SIWB :-)

Also need to take into account that battery capacity tends to go down with time and usage

Tic-tac-toe for scientists... Plus a questions for the mathematicians, how many possible outcomes does this version have?

The game is actually really cool!

this seems like an important improvement: "As many have pointed out, the rules as I've described them are not the best. My gambit is too strong, and can be extended into a guaranteed win for X. So I recommend modifying "Clarifying Rule #1″ to say: If you are sent to a board that's already been won, you may go wherever you like."

This guy solved a problem many people are trying to solve!!! The optimal control problem for the three body problem (restricted, circular) can be solved using continuation of the secondary gravity parameter and some clever adaptation of the boundary conditions!! His presentation was an eye opener ... making the work of many pretty useless now :)

I like when there are discussions evolving around entries

and on your problem with the RSS Tamas: its the same for me, you get the comments only for entries that you have posted or that you have commented on ...

Horizon2020 project on post quantum cryptography just released their first draft of recommendations for quantum computer safe encryption algorithms. No big surprise with the symmetric algorithms (what's used today is fundamentally sound), but the asymmetric public-key methods will be interesting.

In the world of mathematical tiling, news doesn't come bigger than this. In the world of bathroom tiling - I bet they're interested too. If you can cover a flat surface using only identical copies of the same shape leaving neither gaps nor overlaps, then that shape is said to tile the plane. Also only mathematicians can put the words "Pentagon", "attack", and "plane" in the same sentence...

I especially love this part of the story: "The hunt to find and classify the pentagons that can tile the plane has been a century-long mathematical quest, begun by the German mathematician Karl Reinhardt, who in 1918 discovered five types of pentagon that do tile the plane. (To clarify, he did not find five single pentagons. He discovered five classes of pentagon that can each be described by an equation. For the curious, the equations are here. And for further clarification, we are talking about convex pentagons, which are most people's understanding of a pentagon in that every corner sticks out.) Most people assumed Reinhardt had the complete list until half a century later in 1968 when R. B. Kershner found three more. Richard James brought the number of types of pentagonal tile up to nine in 1975. That same year an unlikely mathematical pioneer entered the fray: Marjorie Rice, a San Diego housewife in her 50s, who had read about James' discovery in Scientific American. An amateur mathematician, Rice developed her own notation and method and over the next few years discovered another four types of pentagon that tile the plane. In 1985 Rolf Stein found a fourteenth. Way to go!"

Seems looking into turbulence is a source of innovative concepts. After the black hole modelling here was found a mathematical expression which describes "how turbulence can alter the shape and course of a flock of birds, a swarm of insects or even an algal bloom (phytoplankton!) and could help us to better predict them". More relevant for motions in air and sea, rather than space, where the fluids are dense enough to exhibit turbulence ; but what about a swarm moving in and exploring an exoplanet's atmosphere?

can be helpful ... but also very tricky. There are so many ways to write the same equation...

from Fairouz

Francesco pointed out this research one year ago, we dropped it as noone was really considering it ... but in space a low CPU power consumption is crucial!! Maybe we should look back into this?

I don't remember what is the speed factor, but I guess this might do it! Although, I remember when using an IMU that you cannot have the data above a given rate (e.g. 20Hz even though the ADC samples the sensor at a little faster rate), so somehow it is not just the CPU that must be re-thought. When I say qualification I also imply the "hardened" phase.

I don't know if the (promised) one-order-of-magnitude improvements in power efficiency and performance are enough to justify looking into this. For once, it is not clear to me what embracing this technology would mean from an engineering point of view: does this technology need an entirely new software/hardware stack? If that were the case, in my opinion any potential benefit would be nullified. Also, is it realistic to build an entire self-sufficient chip on this technology? While the precision of floating point computations may be degraded and still be useful, how does all this play with integer arithmetic? Keep in mind that, e.g., in the Linux kernel code floating-point calculations are not even allowed/available... It is probably possible to integrate an "accelerated" low-accuracy floating-point unit together with a traditional CPU, but then again you have more implementation overhead creeping in. Finally, recent processors by Intel (e.g., the Atom) and especially ARM boast really low power-consumption levels, at the same time offering performance-boosting features such as multi-core and vectorization capabilities. Don't such efforts have more potential, if anything because of economical/industrial inertia?

An interesting (free) journal on philosophy, with even some article with mathematics and physics !

Reading the titles somehow reminds me of the most important webpage of the ACT: the Advanced Concepts Generator :-)

have you seen the 2 articles on canonical GR ...!

also check out: "Dogs don't need calculus" (http://www.ingentaconnect.com/content/maa/cmj/2010/00000041/00000001/art00003;jsessionid=ltahkvtsh76n.alexandra)

tobias - please finally put an image to your profile .... :-)