The Universe

[in5omniac]

That's the thing for me. The numbers involved are completely brain frying, and the idea that life only came about once in that huge pool of possibility is, to me, preposterous.

A wee numbers example. If you could drive to the moon in your car, ignoring all the obvious problems, just to drive that distance, at 60 mph, not stopping, not sleeping, not refuelling, it would take you six months.

The sun is 390 times as far away. so it would take you 145 years to drive that far.

It'd be 195 years, no?

Edited December 4, 2014 by in5omniac

[biffer]

It'd be 195 years, no?

Aye. Astrophysics I'm good with. Arithmetic not so much.

[Orraloon]

It'd be 195 years, no?

And to the next nearest star it would take about 416,000,000,000 years. Can you check my numbers? Nae point asking Biffer.

And that would just be a tiny fraction of the distance required to leave our own galaxy.

[Orraloon]

Keep it going chaps truly fascinating (fries ones brain though)

Heard that American / Japanese physicist on TV last night saying the vastness & numbers involved almost guarantees intelligent life out there in the cosmos, suppose we will find out one day in the future.

One of the problems is that even if they do exist the chances of us being able to communicate with them might be very small due to distances involved. A radio signal from our next nearest star would take about 4 years to get here then it would take 4 years for us to send a message back. And, the chances are, that our return message would be something like "Eh? Whit did you say?"

[glasgow jock]

And to the next nearest star it would take about 416,000,000,000 years. Can you check my numbers? Nae point asking Biffer.

And that would just be a tiny fraction of the distance required to leave our own galaxy.

FFS they better master traveling at the speed of light pretty soon if they want to find anything of interest in our lifetimes

[in5omniac]

And to the next nearest star it would take about 416,000,000,000 years. Can you check my numbers? Nae point asking Biffer.

And that would just be a tiny fraction of the distance required to leave our own galaxy.

I'll just take your word for that one

[thplinth]

I was just reading the wiki page on electric charge...

Electrification by friction

Further information: triboelectric effect

When a piece of glass and a piece of resin—neither of which exhibit any electrical properties—are rubbed together and left with the rubbed surfaces in contact, they still exhibit no electrical properties. When separated, they attract each other.

A second piece of glass rubbed with a second piece of resin, then separated and suspended near the former pieces of glass and resin causes these phenomena:

• The two pieces of glass repel each other.
• Each piece of glass attracts each piece of resin.
• The two pieces of resin repel each other.

This attraction and repulsion is an electrical phenomena, and the bodies that exhibit them are said to be electrified, orelectrically charged. Bodies may be electrified in many other ways, as well as by friction. The electrical properties of the two pieces of glass are similar to each other but opposite to those of the two pieces of resin: The glass attracts what the resin repels and repels what the resin attracts.

If a body electrified in any manner whatsoever behaves as the glass does, that is, if it repels the glass and attracts the resin, the body is said to be 'vitreously' electrified, and if it attracts the glass and repels the resin it is said to be 'resinously' electrified. All electrified bodies are found to be either vitreously or resinously electrified.

It is the established convention of the scientific community to define the vitreous electrification as positive, and the resinous electrification as negative. The exactly opposite properties of the two kinds of electrification justify our indicating them by opposite signs, but the application of the positive sign to one rather than to the other kind must be considered as a matter of arbitrary convention, just as it is a matter of convention in mathematical diagram to reckon positive distances towards the right hand.

No force, either of attraction or of repulsion, can be observed between an electrified body and a body not electrified.^[3]

Actually, all bodies are electrified, but may appear not to be so by the relative similar charge of neighboring objects in the environment. An object further electrified + or – creates an equivalent or opposite charge by default in neighboring objects, until those charges can equalize. The effects of attraction can be observed in high-voltage experiments, while lower voltage effects are merely weaker and therefore less obvious. The attraction and repulsion forces are codified by Coulomb's Law (attraction falls off at the square of the distance, which has a corollary for acceleration in a gravitational field, suggesting that gravitation may be merely electrostatic phenomenon between relatively weak charges in terms of scale).

Huh.

What is charge? why are some particles 'negative' while others positive?

[biffer]

I was just reading the wiki page on electric charge...

Huh.

What is charge? why are some particles 'negative' while others positive?

Now you're asking the hard questions.

I can't explain it properly, but its like mass in that it's a fundamental property of matter. I'm pretty sure it's explainable, as 'what is charge' doesn't seem to be as big a question as 'what is matter' - I think its probably explained in quantum electrodynamics but I know of no way whatsoever to put that into any kind of explanation.

[hunchy]

mu mu... which links to the Illuminatus! Trilogy and conspiracy theories

http://en.wikipedia.org/wiki/The_Illuminatus!_Trilogy

Was wondering who would respond first lol

[thplinth]

It is a fascinating thing about science. It first appears to know the universe... while not knowing it all.

E=Mc^2

So taking out the constant

Energy = Mass

Don't understand what Energy is.

Don't understand what Mass is.

Yet set one off against the other and suddenly we understand their inter-relationship quite well. And this is real advancement, not just talk. It is shadows on the cave wall stuff, but brilliant all the same.

[Freeedom]

It is a fascinating thing about science. It first appears to know the universe... while not knowing it all.

E=Mc^2

So taking out the constant

Energy = Mass

Don't understand what Energy is.

Don't understand what Mass is.

Yet set one off against the other and suddenly we understand their inter-relationship quite well. And this is real advancement, not just talk. It is shadows on the cave wall stuff, but brilliant all the same.

You can't just remove the constant that doesn't make any mathematical sense.

[Orraloon]

You can't just remove the constant that doesn't make any mathematical sense.

It's just a question of time before he starts dividing by zero.

Edited December 4, 2014 by Orraloon

[biffer]

You can't just remove the constant that doesn't make any mathematical sense.

Aye you can, you just change the units so it equals 1.

[Orraloon]

Aye you can, you just change the units so it equals 1.

Are you pished?

[biffer]

Are you pished?

Nope. Well a bit. But units are arbitrary, so you can just set them to be whatever you like so a particular constant is 1. That's the whole point of using the electron volt as a unit. It sets the speed of light = 1 so E = m and energy and mass have the same units, making a whack of quantum mechanics a wee bit less complex.

[Freeedom]

Nope. Well a bit. But units are arbitrary, so you can just set them to be whatever you like so a particular constant is 1. That's the whole point of using the electron volt as a unit. It sets the speed of light = 1 so E = m and energy and mass have the same units, making a whack of quantum mechanics a wee bit less complex.

The units have to be consistant on both sides so it doesn't make any sense. If you do a dimensional analysis for energy you'll find that the units are measured in eV for particles and kgm^2s^-2 for larger objects, the dimension for mass is kg. Or am i missing something here ?

[Orraloon]

Nope. Well a bit. But units are arbitrary, so you can just set them to be whatever you like so a particular constant is 1. That's the whole point of using the electron volt as a unit. It sets the speed of light = 1 so E = m and energy and mass have the same units, making a whack of quantum mechanics a wee bit less complex.

A measure of electron volts may have the "Equivalence" to a corresponding unit of mass but it is not "equal" to it. The constant has units as well, you can't just ignore that. Sure the use of electron volts makes the calculations easier for certain things, but it doesn't mean Energy = Mass.

[bajin]

Well it depends on how you define your units. It is very common is some fields of physics to use natural units to simplify equations and make everything more "elegant".

E=m is entirely correct, and dimensionally consistent, if you are using Planckian units of energy and Planckian units of mass.

[biffer]

Energy is in joules. A joule is a kg.m²/s².

So a joule is weight times distance (squared) divided by time (squared). So if instead of using joules, you redefine your standard measure of weight to be some thing else k and your standard measure of distance to be something else j, then as long as j times k(squared) is the same as weight times distance(squared) then you can use whatever units you like. So you tune those so that that your distance divided by time is one, and then Bob's your uncle.

[exile]

Was wondering who would respond first lol

yeah somehow ended up going off on a trivia / conspiracy theory tangent...

[thplinth]

You can't just remove the constant that doesn't make any mathematical sense.

You can if you want to reduce the equation to its variables.

E = M, one varies in constant proportion to the other, whether that constant proportion is 1 or 1 million or the speed of light squared it is just a detail, the point is it is a constant.

The way I read the equals sign is that energy and mass are two physical manifestations of the same thing. Mass appears to bound energy. Energy trapped in a standing wave...

[thplinth]

In the Dawkins Ted talk I posted earlier he describes the atom as mostly space and paints an analogy... The nucleus of the atom is the size of a fly sitting on the centre spot of an invisible football stadium. The electrons (the walls of the stadium) are incredibly tiny in comparison to the fly on the centre spot. The next atom is a similar invisible football stadium sitting next to it with another fly sized nucleus in the middle and so on...So matter is almost completely made of space. The only reason we perceive matter as solid is that we are mostly made of space.

It is some weird shit all right.

[thplinth]

The thing that has always troubled me about E = Mc² is the fact that the speed of light is squared. Surely if we exist in 3 dimensions it should be E=Mc³

edit: anyway is the equation not effectively... Energy = Mass x The speed of Energy² ?

edit: sooo...

Mass = Energy / The Speed of Energy²

So it takes a shit load of energy to make some mass.

Edited December 5, 2014 by thplinth

[Flure]

The thing that has always troubled me about E = Mc² is the fact that the speed of light is squared. Surely if we exist in 3 dimensions it should be E=Mc³

That's a ridiculous position to adopt.

[Orraloon]

Well it depends on how you define your units. It is very common is some fields of physics to use natural units to simplify equations and make everything more "elegant".

E=m is entirely correct, and dimensionally consistent, if you are using Planckian units of energy and Planckian units of mass.

Mathematically, it is an acceptable trick which saves labour. Physically it represents a loss of information and leads to confusion. The introduction of dimensionless units is a sleight of hand used by theoretical physicists who are often prone to assume (wrongly) that any algebraically correct equation can be made physically (ie dimensionally) correct merely by wishing suitable units into existence.

Just because the equation can be manipulated mathematically to make the calculations easier, does not mean that Energy equals Mass. This is an example of the loss of information which the mathematical manipulation brings into play.

Edited December 5, 2014 by Orraloon