Wikipedia:Reference desk/Archives/Science/2016 February 21

= February 21 =

Can identify this dog breed ?
Found this furry male dog in India. Does not bark much, instead makes some high pitch cry when it wants to play or is hungry. The body is white, the face is fully black, and some black patches on the tail. Bobatnet (talk) 05:55, 21 February 2016 (UTC)


 * Looks like a puppy to me, which might make IDing it a bit trickier. Also looks like it's had it's fur trimmed, again complicating matters.  StuRat (talk) 07:08, 21 February 2016 (UTC)


 * Yes, its a puppy. No, it's fur isn't trimmed. Bobatnet (talk) 08:59, 21 February 2016 (UTC)


 * It's probably a mongrel and without knowing the parentage it would be difficult to work out what they were. Richerman    (talk)


 * Bears some resemblance to a Jack Russell terrier to my eye. Alansplodge (talk) 19:28, 21 February 2016 (UTC)
 * Also perhaps some rat terrier in there. Can't be too wrong to call it a terrier mix. SemanticMantis (talk) 17:01, 22 February 2016 (UTC)


 * Then again, it could be a very young border collie. It will be very hard to say with 100% accuracy from this one photo alone. Dismas |(talk) 21:35, 22 February 2016 (UTC)

Brain limit
Weightlifting has two thresholds that i'm aware of that makes further lifting risky; weight limit (over a certain kg); time limit (the recovery period that is needed for muscles to grow). Does brain usage have a similar threshold? If so, what is the name for this threshold? Hawaan12 (talk) 09:17, 21 February 2016 (UTC)
 * See attention span, information overload, semantic satiation, and their linked articles. Tevildo (talk) 09:31, 21 February 2016 (UTC)
 * At a low level (emphasizing the risky part) there is excitotoxicity. (I haven't heard of any evidence that simply thinking too much can cause it though; it is generally associated with more physical causes.  But then again, I haven't looked and I can't rule it out.) Wnt (talk) 18:24, 21 February 2016 (UTC)
 * Yes. It has been used for torture. Specifically the part of the brain that the senses connect to. Though most of the people with info that 21st century torturers want are the kind of human where sensory deprivation or elimination of human contact works much better so this is uncommon. They actually risk beatings trying to anger their feeder enough to verbally abuse them so that the human contact lasts longer, lol. Sagittarian Milky Way (talk) 01:15, 22 February 2016 (UTC)


 * Some evidence exists that parts the human brain can change to accept a large quantity of new information. See Taxi drivers' brains 'grow' on the job about the test known as "The Knowledge" which London cabbies have to pass. Alansplodge (talk) 16:25, 22 February 2016 (UTC)


 * The refractory period during which the brain "grows" is during sleep, when memory is consolidated. μηδείς (talk) 18:08, 23 February 2016 (UTC)

Example for Calculus of Variations Usage
Hi, I am reading about calculus of variations. Could you give me an example to some use for this in physics - I know some examples, but all of which are only in $$\R^2$$ or $$\R^3$$. Is there some example for physics usage of calculus of variations which is in higher-dimension (i.e, in $$\R^n$$ for arbitrary n)? I prefer examples that have no analytic solution. Thanks in advance! עברית (talk) 12:16, 21 February 2016 (UTC)
 * Euler–Lagrange equation in $$\R^n$$. Ruslik_ Zero 19:58, 21 February 2016 (UTC)
 * But this is an equation - it's in theory. I am looking for a usage in practice, in physics. עברית (talk) 13:52, 22 February 2016 (UTC)

Withstanding black hole gravitation
In a purely theoretical thought experiment, what properties should an object have to withstand extreme black hole-like gravitational fields, in the sense of remaining integral and unaffected by spaghettification? Is it about gluons, magnitude of strong interaction or some other cementing property at particle level? Brandmeistertalk  14:55, 21 February 2016 (UTC)


 * Wouldn't that be a simple matter of material strength? --Guy Macon (talk) 18:03, 21 February 2016 (UTC)
 * And the mass of the black hole. Ruslik_ Zero 19:59, 21 February 2016 (UTC)
 * None of that will matter. It's like asking what property is necessary to avoid length dilation in special relativity.  Black holes curve the space and time around them.  Things that occupy space and time will be affected.  --DHeyward (talk) 21:01, 22 February 2016 (UTC)
 * I don't think that objects being stretched by strong tidal forces is the same thing as space being distorted. --Guy Macon (talk) 04:05, 23 February 2016 (UTC)