was wondering about this.why does gravity have such a powerful hold over the universe if according to physicists it is actually very weak? (you can tell that i’m no physicist myself 😉

Newtons law of universal gravitation describes the force of attraction between two objects. which is proportional to their masses, and inversely proportional to the square of the distance between them:

see those m’s up there, they are the masses of two objects attracting each other. There is an enormous amount of m in the universe.

F is the force between the masses,
G is the gravitational constant,
m1 is the first mass,
m2 is the second mass, and
r is the distance between the centers of the masses.

PS I’m not sure I agreee that its a weak force but hopefully that goes some way to describing why its so powerful in the unverse.

The other fundamental forces are all much stronger than gravity BUT gravity is the only one that isn’t polarized. There’s no negative gravity, so it always just adds up resulting in huge forces. It can only pull, it can’t push.

Electromagnetism is very strong but the particles of opposite charge attract each other and tend to cancel out over time as charges flow, and with large collections of objects.

You can’t negotiate with it.

(Not a physicist)

I think “weak” is a relative term.

AS I understand it, it is weaker than the other fundamental forces of nature: electromagnetism, nuclear strong force and nuclear weak force.

e.g. gravity is strong enough to keep our moon in orbit but not strong enough to tear its atoms apart.

It really is very weak. Just stick two magnets together, see how strong it is. Then try two non-magnetic bits of metal and see how hard it is to pull them apart. They are attracted to each other by gravity, but not enough to notice.

Two tiny magnets can exert far more force than one magnet and the entire earth do through gravity, which is why you can pick one up with the other.

Molgrips has the answer I understand. Theoretically though gravity should be as strong as magnetism and electrical force so where is all the extra magnetic force going? ( I once read new scientist but did not understand it)

see those m’s up there, they are the masses of two ‘objects’ attracting each other. The universe is made up of nothing but m (of differing perceived densities).

F is slang for everything including the gaps,
G is perception,
m1 is the first ‘mass’,
m2 is the second ‘mass’, and
r is the perceived distance between the centers of the masses

(it’s all a trick of the light)

Molgrips has the answer I understand. Theoretically though gravity should be as strong as magnetism and electrical force so where is all the extra magnetic force going? ( I once read new scientist but did not understand it)

Trying to remember my A-levels here but IIRC:
There are 4 fundamental forces

Gravity – self explanatory

Weak Nuclear force – I cant remember, but t’s pretty weak and has something to do with radioacitve decay, it forms a field like a magnet.

Electromagnetism – magnets, electrics, light etc.

Strong nuclear force, this is 0 at arround 0.7 femtometer (7×10^16m, a gold nucleus whichis huge by nuclear stndards is about 8.5femtometer), and accounts for the size of a nucleus as it holds the nucleons a fixed distance appart, acting between 2 nucleons (protons or neutrons) it either attracts at longer distances, or repels at closer distances, it’s force decays rapidly with distance, at about 2.5 femtometers it’s effectively 0, hence there is no attaction between 2 nuclei as a result of this force so there’s no evidence of it in everyday life. This force is what gives you the energy and mass in E=mC2 (force*distance=energy, so split the nucleus up so that the force is overcome and energy is released)

So the reason gravity has an effect on a panetary scale is the rate at which it diminishes with distance. Gravity diminishes with the square of ditance, the others act within a field, outside of which the effect is so low as to be effectively zero. So the strong and weak nuclear forces don’t act beyond the nucleus of an atom, the electromagnetic forces are obviously dependant on the size of the source but still have a field (e.g. magnet or the earths magnetic field extending into space) but the earths magnetic field doesn’t affect the sun, unlike gravity which is enough to cause the sun to wobble slightly (which is how we detect palnets arorund other suns, we look for them wobbling).

Gravity is a weak force comparatively. If you look at magnetism two small objects can overcome the gravitational pull of the earth.

what molgrips said

So what’s the gravitational pull of the average STWer?

If a packet of crisps drifts towards me and crosses the event horizon of roughly 3 feet then it’s pretty much doomed.

If a packet of crisps drifts towards me and crosses the event horizon of roughly 3 feet then it’s pretty much doomed.

I suggest to you sir, that it is you who is drifting towards the crisps. 🙂

I love the way physicists get to spend humungous amounts of money trying to find out really quite irrelevant stuff about far away galaxies, tiny particles etc. when this fundamental force, gravity, goes unexplained.

I don’t think anybody has a good explanation for it, knows what fields or particles can cross the void of intergalactic space to keep it working, when, if harnessed, it would be a fantastic free means of propulsion. With a gravity shield, you could reach warp speed in seconds.

The same, more or less, applies to magnetism.

The same, more or less, applies to magnetism.

It’s funny, I had someone telling me how simple magnetism is at the weekend.

the gravitational pull of some forum topics towards some forum members egos is indeed irresistible.

I’ve got animal magentism. It works like humena-humena-humena..

Short video:
[video]http://www.youtube.com/watch?v=p_o4aY7xkXg[/video]

Longer video:
[video]http://www.youtube.com/watch?v=JHhoHmiiXdc[/video]

The same, more or less, applies to magnetism.

Miracles innit? 😉

Theoretically though gravity should be as strong as magnetism and electrical force so where is all the extra magnetic force going?

Theoretically? Under what theory? Got any more info?

I love the way physicists get to spend humungous amounts of money trying to find out really quite irrelevant stuff about far away galaxies, tiny particles etc. when this fundamental force, gravity, goes unexplained.

Absolutely tons of research going into gravity. Much of which is covered in TV documentaries too.

Depends what you mean by “weak” as it acts over much larger distances than magnetism [ TSY animal magnetism aside]

It can bend space and time , hold the moon in place and create tides – you try that with some magnets 😉

Cannot see the videos posted will check them out at home

It can bend space and time , hold the moon in place and create tides – you try that with some magnets

But if you had an electromagnet the size of the Earth (and enough power to run it) then I’m pretty sure you’d get some interesting effects too!!

Cannot see the videos posted will check them out at home

minutephysics and sixtysymbols – you’ve probably already seen them Junkyard.

Isnt it something to do with gravity possibly working in other dimensions? So in the 4 or however many we identify it’s pretty weak.

Is my lack of physicism showing?

Can we get some decent sized electro-magnets installed above the table tops on the White’s Descent at Afan?

I’ve got some serious gravity working on me. 🙁

But if you had an electromagnet the size of the Earth (and enough power to run it) then I’m pretty sure you’d get some interesting effects too!!

Yes i thought of that when posting and it is a fair point

I am just not sure we should describe it as weak [ i know why we do in the physicist sense]. Locally we can easily overcome it. Every time I cycle my bike uphill the power of my awesome legs overcomes the entire mass of the Earth etc

However I am not sure what gearing i would need for an event horizon so would that be “weak” ?

Why is it surprising that it’s weaker than others? It’s just how it is.

The Earth is an giant electromagnet guys, it’s just not very strong compared to your average fridge.

As for the ‘weak’ or ‘strong’ argument, it’s important to keep the distances in mind. It just depends what scale you want to work at.

As for the ‘weak’ or ‘strong’ argument, it’s important to keep the distances in mind. It just depends what scale you want to work at.

So it begins 😐

quantum 😀