Science questions not worth a thread I: I'm a moron!

uppi · Dec 30, 2011

Blue Emu said:
Or, even if possible, whether it would be useful for anything.

It might give us exact equations for solving any conceivable situation... but the equations themselves might be too complex for us to solve.

Oh, we're well beyond that point already. In quantum mechanics, for example, we will never be able to solve a 200 particle system exactly (on a classical computer). We will always need to go for simplifications and effective theories for larger systems.

A more general theory will most likely have to be more complex, as it has to replicate the behavior of quantum mechanics, that we see. So finding a universal theory and then calculating everything with it is never going to happen.

Narz · Dec 31, 2011

Thanks contre, Yeekim. I've read about those Soviet foxes before. The article on wiki on neoteny was interesting too (though it sounds like a hard concept to measure as it's somewhat subjective). I feel a little neotenous (word?) myself, in spirit anyway, not in looks & it's nice to know it's mostly a positive & correlated with intelligence (generally).

Blue Emu · Dec 31, 2011

Stupid question:

What acceleration (in g's) is required in order to accelerate from zero to 2,000 kilometers per second within 200 meters?

Narnia · Dec 31, 2011

Blue Emu said:
Stupid question:

What acceleration (in g's) is required in order to accelerate from zero to 2,000 kilometers per second within 200 meters?

Assuming that acceleration is constant, the formula you need is:
v_f^2=v_i^2+2a∆d
Also, we need to convert km to m, so 2,000km/s becomes 2,000,000m/s
therefore:

((2*〖10〗^6 )*m/s)^2=(0m/s)^2+2*a*200m
4*〖10〗^12*m^2/s^2 =a*4*〖10〗^2*m
(4*〖10〗^12*m^2/s^2 )/(4*〖10〗^2*m)=a
1*〖10〗^10*m/s^2 =a
a=〖10〗^10*m/s^2
a=〖10〗^7*km/s^2
a=10,000,000*km/s^2

Gravity is ~9.8m/s^2. For simplicity's sake, 10m/s. I think that this means that it is about 10^9 times the strength of gravity. (that's a 1 with 9 zeros after it)
Btw, this figure seems a little high, I may have made a mistake. However, I'm not used to working with high figures so...

sanabas · Jan 1, 2012

No mistake, it is 1 billion g.

peter grimes · Jan 2, 2012

Narz said:
I feel a little neotenous (word?) myself, in spirit anyway, not in looks & it's nice to know it's mostly a positive & correlated with intelligence (generally).

As apes go, we are definitely neotenous.

Dawkins has a wonderful chapter on Neoteny in Ancestor's Tale. As he says, once you know what to look for you start seeing it all over the place.

EDIT: just tracked it down - it's the Axolotl's Tale. I really can't recommend this book enough. I've read it 4 or 5 times now, and it's always still informative. It might be my favorite book on evolution.

emzie · Jan 2, 2012

peter grimes said:
As apes go, we are definitely neotenous.

Dawkins has a wonderful chapter on Neoteny in Ancestor's Tale. As he says, once you know what to look for you start seeing it all over the place.

EDIT: just tracked it down - it's the Axolotl's Tale. I really can't recommend this book enough. I've read it 4 or 5 times now, and it's always still informative. It might be my favorite book on evolution.

It really is an awesome book.

Narz · Jan 2, 2012

I'll check it out, I find evolution & it's implications fascinating.

Phrossack · Jan 9, 2012

Sorry to sound stupid, but suppose you have a magnetic piece of metal. Then you melt said piece down and pour it into a mold. Will it still be magnetic when hardened (I'm pretty sure it wouldn't)? If not, would it be possible to re-magnetize it?

madviking · Jan 9, 2012

Magnetism is about the electric dipoles lining up. So when you melt something the dipoles get scrambled, making the material lose magnetism.

If you wanted to remagnitize it, it depends on the material. For iron, I think if you let it cool in an external magnetic field you'll get it back to magnetic.

uppi · Jan 9, 2012

Phrossack said:
Sorry to sound stupid, but suppose you have a magnetic piece of metal. Then you melt said piece down and pour it into a mold. Will it still be magnetic when hardened (I'm pretty sure it wouldn't)? If not, would it be possible to re-magnetize it?

There is a temperature above which the metal loses its magnetization. This is called the Cuire temperature. For all ferromagnetic metals, this is below the melting temperature, so for all metals the melt is not (ferro-)magnetic anymore.

If you then slowly cool down the metal to a temperature lower than the Curie temperature and apply an homogeneous external magnetic field (the magnetic field of the earth can suffice), it will become magnetized again.

edit:

Magnetism is about the electric dipoles lining up.

No, it is about the magnetic dipoles lining up

Narnia · Jan 9, 2012

Speaking of magnetism, can you make a permanent magnet with an electromagnet?

uppi · Jan 10, 2012

Narnia said:
Speaking of magnetism, can you make a permanent magnet with an electromagnet?

Yes, you can use an electromagnet to magnetize a ferromagnetic material so that it becomes a permanent magnet.

emzie · Jan 12, 2012

What would happen if a hypervelocity star smacked into another star? Ignore that such an event would be exceedingly rare

Quackers · Jan 12, 2012

I got a hypothetical.

Me and Uppi are in deep space far away from any strong gravitiational pull and we are alive in our space suits. Suddenly I get an urge to kill Uppi, so in my murderous rage I push Uppi with all my strength. What the hell happens?

peter grimes · Jan 12, 2012

you move away from the point of contact with speeds proportionate to your masses. If you are both 75kg then you'll both have equal both opposite velocity

Quackers · Jan 12, 2012

Does the velocity last forever or untill we reach some gravity?

madviking · Jan 12, 2012

Or acted upon by an outside force; first law of Newton's.

Cutlass · Jan 12, 2012

contre said:
What would happen if a hypervelocity star smacked into another star? Ignore that such an event would be exceedingly rare

Something sorta like a supernova, depending on the masses involved. The collision would compress the plasma of each star far beyond what normal gravity would accomplish, and that would kick off a huge flurry of increased fusion.

Loppan Torkel · Jan 12, 2012

If we, against all sense, did manage to create a spaceship that could travel at the speed of light and planned to send it toward a planet 50 light years away - How large ship would that be? How many people would we send? Would we send several ships at once to the same planet? If they listened to radio from earth - what would they hear?

Science questions not worth a thread I: I'm a moron!

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