We don't know, all we know it provides the majority of the mass of galaxies making them spin faster than the visible matter present would indicate and doesn't interact electromagnetically with normal matter.


Dark energy is something entirely different from dark matter and makes up an even larger part of the universe. Dark matter is why the expansion of the universe is accelerating instead of slowing down or going at a constant speed and we know even less about it than about dark matter.

Well that's gonna get sigged now

Why do people have coloured urine?

And pizza boxes are square.

The wizard likes geometry.

Did you know that, on average, the human intestine is 480 miles long and the food has to travel through it at an average speed of 60 mph in order to get converted into poo in a timely manner?

Some pizzas come in rectangles or squares and some slices come in circular sectors, rectangles, squares or even kites! Madness I say! Madness!

you needed science to figure that out? When we can be bullied into submission by the slightest glimpse of some cleavage and leg?
Geez.., are you simple, or what?

:P

So it isn't mistaken for mouthwash?


My bowls were given a ticket the other day, for speeding

I call that sacrilege, but religious talk isn't allowed, and the church of pizza is still considered heretic by Rome.. -something about who was there first..


Why do bumble bees continue to fly, despite the entire physics community saying that they shouldn't be able to..

Why does buttered toast always fall with the butter down, regardless of height fallen?

Why is it that no matter what the weather forecast, if I wash the car and hang my laundry out to dry, then leave the house without an umbrella, it'll rain?

Why is the initial progress with any given project inverse proportional to the amount of time allocated to the project? Ergo, why does everything always happen in the last minute?

Why was Murphy right?

I did read that men can lactate under the right circumstances. :blink:


Urine is the colour it is because of the chemicals in it.


1. I always assumed it was because the buttered side was heavier than the unbuttered side, creating a very slight imbalance that would tip it downwards, i.e. buttered side down. When you put margarine onto hot toast and it melts right in, the chances of it falling either side are apparently equal.

2. It depends on your local climate. Here in the UK, it is overcast 50% of the time. I kept a weather diary once for a full year and almost every single day the weather was sunshine and showers: it would be cloudy for a few hours, then there would be a brief spell of sun and then later it would rain (or start off raining and then cheer up into sunshine). With all those factors being equal, my perception of the weather was dependent solely on when I was outside. A "good summer" was when the rain fell mostly at night and was sunny when I was walking to work. A "bad summer" was when it rained around lunchtime - the moment I was going outside.

3. The only way to plan a project is to always allocate three times as much to everything as you think you'll need.

4. Yes.

"It is well known that in the males of all mammals, including man, rudimentary mammae exist. These in several instances have become well developed, and have yielded a copious supply of milk. Their essential identity in the two sixes is likewise shewn by their occasional sympathetic enlargement in both during an attack of the measles."
-Charles Darwin in The Descent of Man, and Selection in Relation to six (1871): :grad:


there's actually a http://www.urinecolors.com/ for that



Great.. but what about the bumble bees?!? :mellow:

I just saw *another* one fly past the window!! :ahhh:

That has to do with the relatively large moment of inertia of the toast and table height not being enough for it to make a full revolution, given a reasonable table and initial torque. Try cutting the toast in smaller pieces or use a taller table and you'll see a difference.

What do you all think about black holes and the theory of them actually being "black, imploded suns"? The theory basically says that huge suns have the possibility of exploding and imploding themselves into very small things with incredible gravity. That gravity pulls the light into it, creating the blackness effect. I've got to say, regular black hole theory is quite difficult for me to accept, we are basically talking about an infinitely small and infinitely heavy rip in the universe that is sort of a teleport.. or something. So what do you think?

We did, in highschool (and yes, again it was me who asked), so we dropped butted toast from incremental heights starting at one meter up to four flights of stairs in the central staircase in school.

buttered side face down at all measured heights more than 80% of the time. My teacher at the time put it down to the buttered side being more aerodynamic.. in other words, he didn't know either




And still, bumble bees fly in the face of modren physics, huh?

http://en.wikipedia.org/wiki/Bumble_bee#Myths

thanks

I knew about the effects of dynamic stall, just not that it was in every oscillation cycle.

My dad's answer when I was younger: "No one told the bees this."

:laugh: :laugh: The posts in this threads are very scientific indeed

There is no infinity in nature. That's one of the most important aspects you have to consider in physics.
Infinity is a construct in mathematics to help us to approximate reality.
That's why even Albert Einstein said that the theory of relativity cannot tell what happens in black holes, since the theory says that there is a infinitesimally small singularity inside and that's not possible.
So in a singularity the theory of relativity breaks down, here the effects of quantum theory are relevant.
But unfortunately, until today, there is no proven theory that combines quantum theory and gravity. And therefor, we don't know what really happens in black holes.

We know that gravity is so strong in there, that light is pulled in. We also know that black holes emits thermal radtion, the hawking radiation.
That means it looses energy, shrinks and collapses after some (actually a lot of) time if no energy is absorbed by the black hole.
That's why the 'black holes' that are created in our atmosphere every day and the ones that are created at the collision of lead particles at the LHC in CERN aren't dangerous. They emit hawking radiation and collapse within a veeeeery short time (I don't know how fast, but something about 10^-20 seconds).

It's important to add that we cannot prove black holes until now. We can't see them and the Hawking Radiation they emit is to weak to detect. There are possible ways (radiation bursts) to find them but we haven't yet. The strongest prove of black holes is that they work as gravitational lenses, so they affect the path light takes outside of the event horizon. And that we can see.

It is theoretically possible, that a black hole at two points of the universe twist the space in a way that they connect. That's called a worm hole then. That's a pretty famous topic for science fiction. Unfortunately, you'd be crushed long before you enter the wormhole and the propability that two black holes connect by accident is very low.

This is where quantum Teleportation ties in and creates the idea that 2 items can be seperated by any amount of space, but if one were to enter it, the inside of the black hole would have a constant length between the two, even if the physical length is changed, the inside length does not, which i think is a pretty cool theory.

Someone explained, either on this forum or some other, that time and space work like this. Time 'moves' at the speed of light, and any speed you go in space is borrowed from the speed of time. So, if you were to go 50 miles per hour in your car, you're now traveling 50 miles per hour slower in time. Is this accurate?
If so, then if you were to move a negative speed ( which is impossible, I know ) you would then move forward in time, correct? To move back in time you'd obviously need to move faster than light in space. Does this also mean - again, assuming it's true - that if you were to drive/walk/move more often than somebody else, you would inadvertently become younger than them whilst having seemingly been alive the same amount of time? A final question, building upon the last. Does that mean the parts of your body that move the most, for us PC gamers our hands/arms/etc., are therefore 'younger' than the rest of our body? Since the individual cells that allow us to flex certain parts of our body would be moving more often than the rest.
I'm sure the amount of movement ( specifically the speed ) would be so minuscule it'd hardly have any effect on time, but it'd have an effect nonetheless.

Nice .
Fun fact to teleportation: quantum teleportation isn't 'real' teleportation. You create a perfect clone of yourself and destroy the original. Of course, every atom of the clone is in exactly the same state as the original and so it can be called teleportation. It's just interesting for those who are faithful and believe in the soul: is it transportated too?



That's called the twin paradoxon.

E.g. you have two systems: One is the earth the other is a spaceship that can travel at 66% of light speed somehow.
The destinaton of the space ship is a planet 2.67 light years away.
If you are on earth and calculate the time needed to get to the planet and return to earth you'll get 8 years.
If you are on the space ship due to the relativistic time dilation you only need 6 years for the whole flight.
So when you stay on earth, 8 years pass while for the people on the space ship only 6 years passed.

So generally:
Time slows down when you speed up. But you will not realize it.
The people in the space ship are all aging at the same speed, they don't realize that they live 'longer'. They still live a normal human lifespan in their system.
When people on earth look at you they'd see you living much longer. But when the space ship slows down to enter the intertial system of earth they start to age at the speed of the people of earth.


Twin paradoxon source where I borrowed the example above: http://www.phys.unsw.edu.au/einsteinlight/jw/module4_twin_paradox.htm