Ask any question you want about Physics

a reply to: KrzYma

Refraction does not always involve a prismatic effect. White light can be transmitted through fiber optic cable and still come out as white. And what I was specifically referring to is your reference of light moving through a medium. If I interpreted it correctly, please let me know, but I thought you meant something like a jar of water for instance, since you mentioned it slowing down.

a reply to: pfishy

yes, I mean Eather, or Ether or God's soul... however you like it

please visit my other thread
www.abovetopsecret.com...

a reply to: KrzYma

Ah.
Could you go into a bit more depth on Sagittarius A* being the source of energy for the galaxy?

originally posted by: KrzYma
a reply to: Arbitrageur

When we try to model gravitation on quantum scales we can't discard the infinities through renormalization like we can for the other interactions, so this is a problem when trying to model what happens inside a black hole for example.

is it because gravity is seen as a one way force ?
attraction only and no repulsion ?

Well not entirely true because gravity isn't considered a force according to special relativity. There the bending of space creates gravity waves. In QM it's not even clear its a force and I'm not sure it's useful to think of gravitational "forces," such as the one that sticks you to the earth's surface, as mediated by virtual gravitons. The notion of virtual particles mediating static forces comes from perturbation theory, and if there is one thing we know about quantum gravity, it's that the usual way of doing perturbation theory doesn't work.

So in other words your trying to say science believes it's a force and only works in one direction that's just not true. The closest theory we have to reproducing gravity is string theory and that allows for gravity to repel as well depending on the vibrations. So seems you made a very wrong assumption about what science believes.

Ok, so if we have been able to unify electromagnetic force, the weak nuclear force, and the strong nuclear force, could it be that the reason we can't unify gravity as well is because it has no counter? It is merely a single polarity, so to speak?. And if that's the case, could vacuum or dark energy be the counter force, so that a GUT must properly unify 6 forces to work?

a reply to: dragonridr

OK, than it's not the one way force but the one way bending.
No mass ---> flat
mass ---> not flat, curved

nothing as opposite to it

originally posted by: pfishy
...a single polarity...

I think that's the problem...

originally posted by: KrzYma
a reply to: dragonridr

OK, than it's not the one way force but the one way bending.
No mass ---> flat
mass ---> not flat, curved

nothing as opposite to it

Opisit of gravity would be no gravity. Think of a photon they exist we know they do yet seem to not have any gravity. At least that we can detect

a reply to: dragonridr

Opisit of gravity would be no gravity.

no.. no gravity is the start point for gravity
0.......1....2....3...4

there is no -1

a reply to: dragonridr

Think of a photon they exist we know they do yet seem to not have any gravity. At least that we can detect

a photon is a mathematical construct, useful but with no counterpart in reality

originally posted by: KrzYma
a reply to: dragonridr

Opisit of gravity would be no gravity.

no.. no gravity is the start point for gravity
0.......1....2....3...4

there is no -1

Can't have a starting point if it's not there. That's like going to a horse race without a horse. Not much is going to happen but a lot of disappointed spectators.

originally posted by: KrzYma
a reply to: dragonridr

Think of a photon they exist we know they do yet seem to not have any gravity. At least that we can detect

a photon is a mathematical construct, useful but with no counterpart in reality

I think you mean virtual photons. However photons themselves do exist we can measure them and we can track them that makes them very real.

originally posted by: KrzYma
a reply to: Arbitrageur
Newtonian field of attraction ??
is this not Gravity ??

That's a bit of a misnomer, but that's how Einstein referred to it. It was actually a calculation done by Soldner, before Einstein, based on some incorrect assumptions such as the photon having mass, but Einstein was unaware that Soldner had already done them. So it's a little confusing in words, but the nice thing about the math is that it's pretty clear below and not subject to such ambiguities, which I guess is why physicists prefer math in many cases as a better language to describe what they want to communicate.

...and the other half... ???
how comes a half and not 1/3 or 2/3 or something in between??

The math was apparently a little tricky even for Einstein because he was off by a factor of 2 the first time he tried to calculate the deflection in 1911, but that was 4 years before he published the Theory of General Relativity in 1915, at which time he reviewed his math and found his error and this math shows where the factor of 2 comes from, see the two terms in equation 7, each of which contributes half:

articles.adsabs.harvard.edu...

gravity is the curvature of space in Einstein's world
Newton never even suggested what causes gravity, he only describes "the action" and not "the cause"

Well he did suggest corpuscles of light, and people after him like Soldner tried to calculate how such corpuscles might behave if they had mass, but we now know they have no significant mass so those Soldner calculations were flawed.

originally posted by: KrzYma
is it because gravity is seen as a one way force ?
attraction only and no repulsion ?

No. See section 2.3 on nonrenormalizability of gravity.

a reply to: KrzYma
I don't know what kind of waves you're talking about or what physical term you're calling "magnitude". For light, or EM radiation in general, shorter wavelength (higher frequency) means higher energy per photon, per the formula E=hf where E is energy, h is the Planck constant, and f is the frequency.

originally posted by: dragonridr

originally posted by: KrzYma
a reply to: dragonridr

OK, than it's not the one way force but the one way bending.
No mass ---> flat
mass ---> not flat, curved

nothing as opposite to it

Opisit of gravity would be no gravity. Think of a photon they exist we know they do yet seem to not have any gravity. At least that we can detect

Because they have no rest mass. However, they do have a stress-energy tensor that can cause a similar effect.

originally posted by: Arbitrageur

originally posted by: John333
i have a couple questions.

what is the speed of light?
how large is the ovservable universe?
how old is our universe?

Unless you need to do precise calculations, 300,000,000 meters per second is easy to remember and pretty close to the speed of light in a vacuum.
The observable universe might be something like 93 billion light years in diameter today but of course we can't see all of it today...the further away we look the further back in time we see.
The big bang is thought to have happened about 13.8 billion years ago.

ok

so the big bang happened in the center of the universe correct? and matter spread out in all directions creating a diameter of 93billion light years so far observed. so we've got planets and star systems that are at least 47billion light years from the center(radius).

my main question is this.

how did matter travel 47billion light years in all directions, in just 13.8 billion years?

originally posted by: John333

how did matter travel 47billion light years in all directions, in just 13.8 billion years?

The space between the matter expanded as well. It's not just matter on a ballistic course. From the matter's POV, it's moving in Einsteinian space, but the metric is expanding as well.

The question you SHOULD ask is, if all the matter was in one relatively small volume to begin with, why didn't the Universe fizzle into a black hole?

originally posted by: Bedlam

originally posted by: John333

how did matter travel 47billion light years in all directions, in just 13.8 billion years?

The space between the matter expanded as well. It's not just matter on a ballistic course. From the matter's POV, it's moving in Einsteinian space, but the metric is expanding as well.

The question you SHOULD ask is, if all the matter was in one relatively small volume to begin with, why didn't the Universe fizzle into a black hole?

is this scientifically recognized or is it your explanation?

to summarize. you're saying that while matter was travelling.. empty space itself is expanding from empty space behind it? so the empty space that is here today is not the same empty space that will be there tomorrow because it was replaced and added to by additional empty space that came from nowhere. causing matter to travel 3x faster than the speed of light to reach it's current position on the outer fringes of the observable universe?

if so can you explain how it was deduced that empty space is expanding/multiplying itself as it were? is it because the longer you look the more you see?

a reply to: John333

Couple of misconceptions here first being there is no center of the iniverse. Realize space is expanding everywhere. So when new space is created that space creates more space and so on. But now because space is getting bigger the distance between objects increase. So in your example we could look at a galaxy 13.3 billion (think this is the oldest we've found if I remember correctly) meaning the light traveled that distance to get here. By now that same galaxy is probably closer to 30 billion. If we continue to observe it we will see it move further and further away. But we can never truly see its current position because the time it takes light to get here.

originally posted by: dragonridr
a reply to: John333

Couple of misconceptions here first being there is no center of the iniverse. Realize space is expanding everywhere. So when new space is created that space creates more space and so on. But now because space is getting bigger the distance between objects increase. So in your example we could look at a galaxy 13.3 billion (think this is the oldest we've found if I remember correctly) meaning the light traveled that distance to get here. By now that same galaxy is probably closer to 30 billion. If we continue to observe it we will see it move further and further away. But we can never truly see its current position because the time it takes light to get here.

please clarify?

there was a big bang in a vaccuum but matter didnt travel in all direction like in an explosion from the center of that explosion? so it is incorrect for me to visualize the creation of an expanding sphere of matter whose, center and starting point was the point where the big bang occurred? are you referring to the pennies stuck on a balloon while its being filled with air explanation?

isnt it more sensible to visualize that after an explosion in a vaccuum, all the matter simply kept on travelling away from the center and so this the space between objects is constantly increasing here in an infinite void of empty space?

originally posted by: John333
so the big bang happened in the center of the universe correct?

incorrect. We are not aware that the universe has any "center" and there doesn't appear to be any place in the universe we can point to and say "That's where the big bang happened.

and matter spread out in all directions creating a diameter of 93billion light years so far observed. so we've got planets and star systems that are at least 47billion light years from the center(radius).

Close, but the fact it's observABLE doesn't mean it's been observed. We will be observing more and more of it as we use better telescopes to do it.

my main question is this.

how did matter travel 47billion light years in all directions, in just 13.8 billion years?

That is a question many people arrive at sooner or later, where if you combine the logic that "nothing can go faster than light" with "the universe is 13.8 billion years old", then the radius shouldn't be any bigger than 13.8 billion light years. But, that's not the way it works. I can provide a good technical reference on this if you want to read more but it gets into math.

It didn't "travel" in any conventional sense, it couldn't as it would have to go faster than the speed of light and that's impossible. What happened was the space between galaxies expanded, and as it turns out metric expansion of space can result in apparent recessional velocities greater than the speed of light without breaking any laws of physics.

originally posted by: John333
causing matter to travel 3x faster than the speed of light to reach it's current position on the outer fringes of the observable universe?

Again displacement via the metric expansion of space is not the same as traveling THROUGH space. The latter is limited to the speed of light, the former is not.

if so can you explain how it was deduced that empty space is expanding/multiplying itself as it were? is it because the longer you look the more you see?

I think it's time to give you the technical reference, as it gets technical, but the answer to this question can only be simplified so much. If you really want to know, you need to read this:

Expanding Confusion: common misconceptions of cosmological horizons and the superluminal expansion of the universe

We use standard general relativity to illustrate and clarify several common misconceptions about the expansion of the Universe. To show the abundance of these misconceptions we cite numerous misleading, or easily misinterpreted, statements in the literature. In the context of the new standard Lambda-CDM cosmology we point out confusions regarding the particle horizon, the event horizon, the ``observable universe'' and the Hubble sphere (distance at which recession velocity = c). We show that we can observe galaxies that have, and always have had, recession velocities greater than the speed of light. We explain why this does not violate special relativity and we link these concepts to observational tests.