Math Is Fun Forum

lolcats2323

Guest

physics questios

I'm no physicist, but I just have some questions...

1) The universe is expanding, correct? This means that its centre of mass is constantly changing, and the centre of the universe is also constantly changing (well... if the universe is spherical, and was increasing in proportion to a sphere). Is this why our Solar System is moving?

2) Does the universe have a gravitational force?

3) Do we define the universe as a finite space?

4) What is at the edge of the universe?

5) Is nothingness possible to exist, or is it simply a phenomenon that cannot exist?

6) Is the universe moving? If yes, then would this imply that there would have to be an object with a greater mass than the universe, causing it to move due to gravitational pull?

7) Neutronium, found at the core of a neutron star, has a neutral charge. Does this mean that, if I touched it, it would be difficult to get it off of my hand? Bonds between atoms cause "stickyness" but what are these bonds made of, and what part do neutrons play in this "stickyness"?

8) Why can't neutronium exist on Earth? Why can't I hold it in my hand?

9) What happens when you split an electron? I heard that, if you took an electron ( say it had a charge of 1 ), and you split it (how would you do this, anyway?), would the two new electrons created (if that is what happens, if not what happens?) have charges of 1/2 and 1/2 respectively?

10) http://upload.wikimedia.org/math/e/1...3581cf9d0f.png
http://upload.wikimedia.org/math/7/c...0241d6023c.png

Is there a reason why there is a link between these two formulae (by that I mean -- they look rather similar).

Thanks.

*11) Extra question -- why is the lowest temperature possible -273 degrees celsius?

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: physics questios

Hi lolcats2323;

Welcome to the forum!

If someone were to drop a neutronium peach onto your outstreched hand it would crush it and  then hit the ground. To quote T. McNeil and J.Straight:

It would plunge through the 4,000 miles of rock, magma  and iron like a bullet fired through a light fog, barely slowing down at the center of the earth before heading back to the surface on the other side of the planet. It would zip up and down like a demented yo-yo on progressively shorter trips to and from the core before finally settling down, leaving the Earth riddled with peach sized holes. Earthquakes and volcanoes and a bad Micheal Bay movie would ensue.

You see it would weight several hundred million tons.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Devantè

Real Member

Registered: 2006-07-14

Posts: 6,400

Re: physics questios

9) What happens when you split an electron? I heard that, if you took an electron ( say it had a charge of 1 ), and you split it (how would you do this, anyway?), would the two new electrons created (if that is what happens, if not what happens?) have charges of 1/2 and 1/2 respectively?

To my knowledge, you cannot split an electron. At least, not according to the very well established quantum theory of electromagnetism and electrons. As far as current scientific knowledge, the electron is not divisible.

5) Is nothingness possible to exist, or is it simply a phenomenon that cannot exist?

By definition, nothingness can't exist. I'm pretty sure mathematics defines this well as the 'null set'.

1) The universe is expanding, correct? This means that its centre of mass is constantly changing, and the centre of the universe is also constantly changing (well... if the universe is spherical, and was increasing in proportion to a sphere). Is this why our Solar System is moving?

Think of the balloon analogy for a 2-dimensional universe. The universe is on the surface of the balloon, which is expanding. Points on the balloon move away from each other as it expands. Even though the universe is expanding, it doesn't make sense to talk about motion of a centre of mass.

8) Why can't neutronium exist on Earth? Why can't I hold it in my hand?

Neutrons by themselves are unstable and decay into a proton and electron with a half-life of about 15 min. Without protons in the right ratio, as in a nucleus, to stabilize the neutrons, your neutronium will decay away. It's only when there is enough pressure from gravity to prevent this decay that you can have stable neutronium.

Identity

Member

Registered: 2007-04-18

Posts: 934

Re: physics questios

4) What is at the edge of the universe?

If there were an 'edge' to our universe, that would imply that there was something outside of our universe. But our 'universe' IS space and time, so there isn't an 'outside'.
Some theories say that the universe is analogous to a 'curled' up sphere. Imagine walking on the surface of a sphere, there is no edge. No matter which way you walk you will still be on the sphere. However, if you go to a higher dimension (beyond the 4 space-time dimensions), you may be able to enter a parallel universe, which is 'layered' on top of our own.

6) Is the universe moving? If yes, then would this imply that there would have to be an object with a greater mass than the universe, causing it to move due to gravitational pull?

There is no evidence to show that the universe is moving. Even if it were moving, what would it be moving 'into'? (there is no space outside our universe)

11) Extra question -- why is the lowest temperature possible -273 degrees celsius?

Take a gas and put it in a container. Then heat the container, measuring the Pressure inside the container at specific temperatures.

If you draw a graph of Pressure vs. Temperature, you'll find that it's linear, and if you continue the graph to the T-axis intercept (where pressure is zero), the value you will get is -273 degrees celcius.

In other words, -273 degrees celcius is the temperature at which the molecules in a gas have no kinetic energy (thus exerting no pressure on the walls).

We aren't able to cool something down to absolute zero (it's very hard to keep a molecule absolutely still), but we have gotten very, very, very close.

By the way, the links to Q10 seem to be broken, I can't access them

Ricky

Moderator

Registered: 2005-12-04

Posts: 3,791

Re: physics questios

We aren't able to cool something down to absolute zero (it's very hard to keep a molecule absolutely still)

If you were able to get something down to absolute zero, then you would violate the laws of thermodynamics.  They can be summed up as:

1. You can't win.
2. You can't break even.
3. You can't stop playing the game.

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"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."