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Stupid Science Questions 2

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06:13 / 12.04.05

I tried to do some research last night on this but after wading though kiddie science sites (good fun those) and some others, I think that's pretty much the drift of it.

Although this is all theory, can't see how we can ever prove or disprove this as the nearest black hole is still ages and ages away.

06:28 / 12.04.05

It is possible for white holes to exist and not exist at the same time, that happens all the time in quantum physics.

13:12 / 12.04.05

No-one really knows what happens to matter that falls into a black hole (it's not really "sucked" - that implies pressure rather than gravity). The basic idea of a body so massive that nothing can escape its gravitational pull (including light) has been around for a long time, but there's never been a satisfactory answer to what happens to the material that passes into the black hole.

You can extrapolate from conventional physics to say that the material gets smaller and smaller and is crushed down to a singularity of infinitely small size and infinitely high density. The problem with that (apart from boggling the mind) is that at some point quantum mechanical effects become important, and there is currently no satisfactory quantum theory of gravity.

Lots of brainiacs of Hawking-order magnitude are trying to crack this problem, and there's been much to-and-fro about whether black holes really are one-way, if they leak matter and information back out, or if they will at some future date blow up or evaporate. (The stuff coming back out would usually bear no real-world resemblance to the stuff going in, incidentally). But there's no generally accepted answer yet.

As for white holes and wormholes: the equations that describe gravity within Einstein's theory of general relativity can be solved in various ways, depending on the particular problem you're considering and the initial conditions. One solution describes black holes (actually, there are a number of solutions and corresponding types of black hole); another describes wormholes; others describe things up to and including the large-scale behaviour of the entire universe.

It was thought for a while that black holes might be the same thing as one end of a wormhole, with the other end being a "white hole" where everything comes back out. That turns out not to be the case. Wormholes (and white holes) remain theoretically possible, but do not necessarily exist in practice, and there's not observational evidence that they do. A collapsing star won't form one. It's been a long time since I paid any real attention, but I believe there's still considerable debate as to whether a wormhole can be made in the first place, and if it could be made stable or traversible if it could.

22:58 / 12.04.05

from black holes to string theory - of a sorts...

why is it that i am appalling at tying knots when i need to [i was never a boy scout and if i had been i would have failed that bit. really, i am bad] but when i try to undo me best efforts at a shoelace i find an intractable knot that would have been most handy last week for the load on a trailer..??

15:27 / 13.04.05

That'd be knot theory. I have no real idea what the answer is (I have exactly the same problem with knots) except to guess that there are more ways for a knot to collapse to a small, tight, fingernail-destroying ball than to unravel cleanly.

Or to put it another way: there are lots of ways of arranging two shoelaces that won't keep your shoes one, but only one (or a few) that will. If you have trouble finding that one correct solution when you're doing them up, you're unlikely to pick the single reverse solution the knot when you undo it. Or something.

21:07 / 24.05.05

Anybody know how to translate "H" (a measure of the apparent magnitude of an asteroid) into actual meters/feet/whatever unit of diameter?

Googling for "H" is a miserable affair.

22:30 / 24.05.05

H is an asteroid's absolute magnitude, the visual magnitude the asteroid would have if it were located 1 astronomical unit, or AU from Earth.

An AU is equal to the mean (average) distance from the Earth to the Sun, about 93 million miles (150 million km). It takes a beam of light about 8.3 minutes to travel 1 AU.

this doesn't really help, does it. from a bad astronomical glossary actually, it's pretty useless, or is your physics up to scratch to work it out? or try this

not my field, just googled 'magnitude of asteroid' - the answer was in your hands all along, grasshopper...

15:11 / 25.05.05

Seems like I can't get D from H unless I have the albedo, too -- the pV. Dammit.

Oh, well. It's only for goofy tabloid stories, anyway.

02:33 / 26.05.05

aah, then, just make it up!

10:29 / 26.05.05

What is the connection between R.E.M sleep and dreaming? I know that it is supposed to correlate with the brain patterns that indicate dreamsleep, but how do we know these patterns actually result in dreaming? This question is asked in response to a friend who thinks that dreams are the result of panicked neuron firing upon unexpected awakening.

19:04 / 26.05.05

I believe (off top of head, took a psych class in dreaming ages ago) that the link between REM and dreaming was initially made because scientist types noticed eyes moving and said, "Hey, that dude must think he's lookin' at stuff!"

I believe they've also removed a portion of cats' brains (hypothalamus?) that would normally keep the whole body from moving around during REM. The result: cats that were like runnin' and jumpin' all over the place, reacting to things that weren't actually there. The same brain area is blvd to be responsible for sleep paralysis episodes, when it doesn't turn off in time for wakeys.

I remember the moral of the class was... Dreams are pretty complex things, and it's not really certain what causes what, or what parts of sleep do what parts of dreams.

Brain scanning tech has probably advanced a bit since then.

01:18 / 27.05.05

bit of info here on rem and non-rem dreams.

no-one still really knows what sleep is and i gather, even from this article, that we are guessing a bit about dreams. i have been recording some of my dreams in a journal recently but wonder that, if i only remember the last dream i had before waking (admittedly at odd hours through the night, in part the cause of keeping the jornal!), then what import are the others i have and don't remember? is there a significance about the emotional response that triggers waking from the dreams i feel are so vivid i can recall them and record them??

14:31 / 27.05.05

Thanks a lot, guys. Astro, your link seems to be broken.

16:00 / 27.05.05

It's a stray _blank at the end of the tag. Will fix now... (should be yadda.htm target="_blank" rather than yadda.htm_blank.)

A beautiful tunnel of ghosts

09:11 / 11.07.05

Within the accretion disc of a black hole, would everything be light, as the black hole is drawing all the available light into it? And how is time theorised as passing within a black hole? Apologies if this is vague or misinformed, but I'm genuinely curious to know.

Cheers!

11:48 / 11.07.05

This should help answer your questions.

A beautiful tunnel of ghosts

12:22 / 11.07.05

Thank you *so* much!

12:58 / 11.07.05

Don't thank me, thank the magic of Google.

A beautiful tunnel of ghosts

13:16 / 11.07.05

*embarrassed*

14:44 / 26.07.05

I've managed to obtain a decent A-level in Physics and a good degree in Mechanical Engineering but something that seems to be so simple and fundamental aludes me.

What the fuck is voltage?

I get current and resistance, they seem pretty intuitive, but I've never been able to wrap my head around the big V.

Has anybody had an 'Eureka' moment with voltage and if so could you share your insight please.

15:08 / 26.07.05

Voltage is one measure of current. Amperage is the other. Put them together (volts x amps), and you get watts.

The standard metaphor is of a hosepipe -- the pressure = voltage (how much water is coming out), the speed of flow = amperage (how fast the water is coming out).
Resistance screws with the pressure, just like squeezing the hose.

More here.

16:26 / 26.07.05

I'm not doubting you Grant but I've never heard voltage being refered to as a measure of current.

I think the problem I have is that the units don't really make any sense.

Charge = Coulomb - OK, I get that, no problem.

Current = Ampere = Coulombs/Sec - Still makes perfect sense

Voltage = Volts = Joules/Coloumb - WTF?!

I can't conceptualize energy per coulomb.

Actually, after reading that I think I may have had an epiphany. So voltage is simply how much energy each little bit of charge contains like the energy that a bit of water in a hosepipe has. Increase the pressure (voltage) and the amount of 'force' (charge) that each bit of water has increases?

18:28 / 26.07.05

Yes, I think you've got it.

10:12 / 08.08.05

Is the human body better equipped to survive one of the two extremes of temperature? Most of the people I work with complain excessively about the heat when the air conditioning breaks, whereas I quite enjoy the almost womb-like atmostphere this creates. In the winter, however, when everyone else is being briskly efficient in the freezing cold, I am the one wearing four pairs of socks and wondering how easy it would be to knit myself a garment which would keep my nose warm yet also be inobtrusive. Is there any evidence that either extreme is easier to cope with, or is it just that different people react differently?

09:48 / 09.08.05

Good question Vincennes. I've often wondered that myself. Unfortunately I don't have the answer, but am here with a question of my own.

There seems to be a general belief that we only use a certain percentage of our brains. It's one of those expressions that pops up every now and then but I am interested in the scientific view. Firstly, is it true, and what is the percentage? A few related questions:

How do we know that?
Are there whole parts of our brains that appear not to control any parts of our bodies?
How extensively have these parts of the brain been studied?
Is there an evolutionary explanation of why we would have these sections of our brains that we don't use?
Did we use them in the past?

10:17 / 09.08.05

Vincennes: Though I cannot remember where I read it I did read in the paper recently that men prefer the temperature to be colder, while the reverse is true of women. Also I found this on the interweb. "Most studies suggest that comfort and mental vigor are not entirely synonymous. Andris Auliciems of the University of Toronto found that English schoolchildren performed best on a variety of tests at temperatures of 58.5 to 62.9 degrees. Some bioclimatologists have put the optimum temperature as high as 82 degrees; others dismiss such correlations as worthless." So there you go.

10:37 / 09.08.05

Loomis: There is a useful website that demolishes that 10% myth here
and also explains how it may have arisen. And it's aimed at kids, so even I could understand it.

12:13 / 09.08.05

Excellent. Thanks Phyrephox. I guess I don't have to feel lazy anymore for not developing that extra 90% of my brain.

18:42 / 09.08.05

I bet that means the rumour that London cab drivers use up to 25% of their brain from remembering the street names isn't true, either...

Cheers for the answer to my question Phyrephox!

02:13 / 16.08.05

How is the human bodies' perception of hot and cold calibrated? Meaning, what is it that determines that mid-point between something being perceived as hot and as cold? I would think that the bodies' internal temperature would make a sensible median, but that doesn't seem to be the case — rather than being at 98.6ºF, it's more like 72ºF. So what determines this?

(Sorry if what I just wrote is confusing — I had a very hard time trying to figure out how to phrase this.)

ORA ORA ORA ORAAAA!!

09:31 / 17.08.05

I vaguely remember a perception course from some time ago, and as far as that memory goes: It's based on the temperature of the skin that's sensing the hot/cold input.

That's why, if you have cold hands, sometimes they can feel perfectly normal (maybe a bit clammy) to each other, but if you put them on your warm and protected stomach, they don't. At all.

The reason being that you can only really feel heat (or its absence) when it moves around, if the thing you're feeling is exactly the same temperature as your sensor, there's no flow of energy (the flow being from hotter object to colder object), and thus nothing to sense.

This may also be the reason why you test bathwater for babies with your elbow - hands tend to be different from your actual temperature more often than your elbows, being moved around in the air more, and having more blood vessels and less insulation. Than your average elbow. For instance.

I was told that it's because you can jerk your elbow out of the water faster if it is too hot, but this seems a) wrong and b) to assume that you're a bad parent who cannot master the simple art of running a bath at a reasonable temperature.

Hope that helps, and isn't too rambly.

13:15 / 17.08.05

Might also be worth considering that 98.6 is the *body core* temperature, and that all the other foofawraw surrounding that body core (like arms, legs, shivering skin) is really there just to keep that core temperature the same.

21:50 / 17.08.05

I bet that means the rumour that London cab drivers use up to 25% of their brain from remembering the street names isn't true, either...

actually, no this probably based in some truth. the percentage might not be quite accurate, but we use a good portion of our brain in a way that maps reality in some form onto neural networks that incorporate different parts of the brain that play different roles in the overall cognitive or nonconcious effects. the effort of mapping huge intricate tracts of reality, like london, as opposed to the fairly easy task (comparitively) of mapping the much smaller landscapes of each our own realities probably means that they have prodigious extents of networks that we don't ever acquire.

this one to one mapping of reality in neural networks is a critical leap in understanding what our brains do and how consciousness manifests. all fascinating stuff and about as explored as the ocean floors. almost not.

01:53 / 18.08.05

Loomis

I read a fairly crappy book recently " A Brief History Of Tomorrow" which claims that modern fMRI and PET scanning seems to show that our brains are already being worked to full capacity and that there are already nueroplacticians working on expanding that capacity. No idea how respectable this evidence is.

01:37 / 21.08.05

this account of the evidence seems pretty much to be the case as accepted doctrine in neuroscience today. a glance at susan greenfield, antonio damasio, elkhonon goldberg will be good insights into just what we know about the brain and how it works.

the concept of 'we only use 10% of our brain' emanates, i suspect, from the early work that provided insights into the role of the frontal cortex lobe plays in how we form concepts; and how this acts as something of a conductor to the orchestra of areas of the brain involved in any given exercise, like making sense of words, finding food or raising your left foot. ten percent of the brain puts the other bits together for us (whoever 'we' are!) and we get 'consciousness', an endless conundrum left to explain just what 'consciousness' is, but that is another story altogether.

its lots of fun, this brain science, and there is so much to explore.

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