Ask a physicist anything. (2)

Chesterton · Nov 30, 2009

A single photon can't be divided or weakened, can it? If you shine a light at an opaque object, most of the light bounces off, but some is absorbed, right? Does that mean some of the photons are fully absorbed, or all of the photons are partially absorbed?

Also, imagine a hypothetical spherical room, the inside of which is completely made of one mirror (no seams). If you could flick a light on and off once inside the room, how long would the light bounce around in there?

Nabobalis · Nov 30, 2009

Wiccan_Child said:
Nope, that's pretty much bang on! That's why a photon appears to travel slower when passing through a medium: there is a small delay between absorption and emission, which means the photon takes every so slightly longer. Between emission and absorption, it's travelling at full light-speed.

Of course, this relies on the atom emitting the photon in the same direction as it was coming. The odds of this happening depends on the material in question: glass lets light 'through' more easily that a steel girder, though the former can become opaque if thick enough, and the latter is transparent if thin enough.

And then there's mirrors and even exotic materials with negative refractive index, which muck everything right up.

If I remember what I was told in my lecture, the reason why light from the sun is about 30-40,000 years old.

Cabal · Nov 30, 2009

Chesterton said:
A single photon can't be divided or weakened, can it? If you shine a light at an opaque object, most of the light bounces off, but some is absorbed, right? Does that mean some of the photons are fully absorbed, or all of the photons are partially absorbed?

Attenuation of light is due to full absorption/scattering of some of the photons.

Also, imagine a hypothetical spherical room, the inside of which is completely made of one mirror (no seams). If you could flick a light on and off once inside the room, how long would the light bounce around in there?[/QUOTE]

Depends on how the reflecting surfaces absorb the energy from the light.

There are reflecting devices one can make that can support indefinite reflection; I know there's a research group in France that has an optical cavity that can contain one photon bouncing around in it indefinitely.

Wiccan_Child · Nov 30, 2009

Chesterton said:
A single photon can't be divided or weakened, can it? If you shine a light at an opaque object, most of the light bounces off, but some is absorbed, right? Does that mean some of the photons are fully absorbed, or all of the photons are partially absorbed?

All of them are absorbed. Some are then re-emitted, which gives an object it's colour. The direction and cohesion of the emitted photons (are they emitted in the same way they were absorbed, or are they emitted in random directions?) determines whether it's a shiny metal, a transparent glass, an opaque wall, etc.

Chesterton said:
Also, imagine a hypothetical spherical room, the inside of which is completely made of one mirror (no seams). If you could flick a light on and off once inside the room, how long would the light bounce around in there?

It would depend on the efficiency with which the walls reflect light, the spectrum of emitted light, the number of photons, the size of the sphere, and even where the the photons were created.

It would boil down to 'how many times could the photons bounce back and forth before the wall has absorbed them all?', so the main feature is how reflective (or absorbing) the mirror is.

Nabobalis said:
If I remember what I was told in my lecture, the reason why light from the sun is about 30-40,000 years old.

It's actually in the order of several million years old. Though this is how long it takes the energy from fusion to escape the Sun; technically, the individual photons are irrevocably destroyed when they're absorbed, and a new one is created when the energy is emitted.

Wiccan_Child · Nov 30, 2009

Cabal said:
There are reflecting devices one can make that can support indefinite reflection; I know there's a research group in France that has an optical cavity that can contain one photon bouncing around in it indefinitely.

Indefinitely? I find that... unlikely .

Cabal · Nov 30, 2009

Wiccan_Child said:
Indefinitely? I find that... unlikely .

*reviews lecture notes*

Yowzer, I remembered that one incorrectly.

I think it's Laboratoire Kastler Brossel, and their microwave superconducting cavity can confine a single photon for 130 ms. Tiny bit different there *cough*

1.4 billion bounces on the mirrors, equivalent to a distance of 39000 km.

Wiccan_Child · Nov 30, 2009

Cabal said:
*reviews lecture notes*

Yowzer, I remembered that one incorrectly.

I think it's Laboratoire Kastler Brossel, and their microwave superconducting cavity can confine a single photon for 130 ms. Tiny bit different there *cough*

1.4 billion bounces on the mirrors, equivalent to a distance of 39000 km.

I recall someone 'freezing' a photon in place. This goes against my religious beliefs regarding how photons move. Though it does reinforce my idea that there are no such things as waves or wave-particle duality: it's particles, all the way down.

Chesterton · Nov 30, 2009

Wiccan_Child said:
I recall someone 'freezing' a photon in place.

Are you talking about the lady at Harvard? Some team there claimed they slowed light down to about 35 miles per hour, and then later they stopped it completely for a fraction of a second.

Doveaman · Nov 30, 2009

Wiccan_Child said:
An ionised gas is called a plasma.

Yes, a plasma that carries charged particles that form electric currents.

I can't believe I'm having to explain this.

Well, you did say “Ask a physicist anything”.

Doveaman said:
Doveaman said:

If it's an electric current then the earth and all the planets in our solar system are electrically connected to the sun, are they not?

Then we are living in an electric solar system, right?

Click to expand...

If you want to use such phraseology, sure.

I do.

Here are some additional observations about our Universe:

Since the sun generates electric currents then it is logical to conclude that the sun is an electrified body.
Since the electrified sun is also a star then it is logical to conclude that stars are electrified bodies.
Since galaxies are made up of electrified stars then it is logical to conclude that galaxies are electrified bodies.
Since the universe is made up of electrified galaxies then it is logical to conclude that we are living in an Electric Universe.

Planets are electrically connected to stars just as our earth is electrically connected to the sun, stars are electrically connected to galaxies, and galaxies are electrically connected by cosmic electrical power lines called Birkeland currents generated in cosmic plasma.

Stellar flares, novas, and super novas are visible evidence of a star’s electrical connection to its parent galaxy where the star receives its electrical charge input from the galaxy through Birkeland currents, sometimes resulting in stellar electrical surges that lead to stellar electrical discharges:

Eventually the star returns to its normal state just as the sun does after a solar flare discharge. No collapse.

Because galaxies are electrified bodies formed from cosmic plasma they generate electromagnetic fields. Electromagnetic fields generate a force 39 orders of magnitude (1000, trillion, trillion, trillion times) more powerful than gravity. It is the force of these electromagnetic fields that holds the galaxies together and drives them in the form of Electric Galaxies:

No dark matter or black holes are necessary.

I know you are the resident physicist here, but you and I both know you don’t have all the answers to every question, so I thought I would offer you some assistance. You don’t have to thank me. In fact, I know you won’t. Oh, well...

Cabal · Nov 30, 2009

^

*smell of burning martyr itt.....*

Wiccan_Child · Nov 30, 2009

Chesterton said:
Are you talking about the lady at Harvard? Some team there claimed they slowed light down to about 35 miles per hour, and then later they stopped it completely for a fraction of a second.

That might be it, actually. I read it in passing, I don't know exactly where.

Wiccan_Child · Nov 30, 2009

Doveaman said:
I know you are the resident physicist here, but you and I both know you dont have all the answers to every question, so I thought I would offer you some assistance. You dont have to thank me. In fact, I know you wont. Oh, well...

I appreciate the help of the other physicists here, particularly when I'm not around to make posts myself (Cabal, I'm looking at you ), but spouting second-rate pseudo-science does not constitute 'help'. We can debate EU by all means, but not in this thread. This is for people to ask questions on physics and science, not for you to espouse your own personal opinion, however much you may believe it.

Cabal · Nov 30, 2009

Wiccan_Child said:
I appreciate the help of the other physicists here, particularly when I'm not around to make posts myself (Cabal, I'm looking at you )

g'yawwww ya big lug

but spouting second-rate pseudo-science does not constitute 'help'. We can debate EU by all means, but not in this thread. This is for people to ask questions on physics and science, not for you to espouse your own personal opinion, however much you may believe it.

It's not so much the pseudo-science I mind so much as the melodramatics....

Doveaman · Dec 1, 2009

Wiccan_Child said:
I appreciate the help of the other physicists here, particularly when I'm not around to make posts myself (Cabal, I'm looking at you ), but spouting second-rate pseudo-science does not constitute 'help'. We can debate EU by all means, but not in this thread. This is for people to ask questions on physics and science, not for you to espouse your own personal opinion, however much you may believe it.

Cabal said:
It's not so much the pseudo-science I mind so much as the melodramatics....

Occam’s Razor Facts:

Occam's razor is the principle that "entities must not be multiplied beyond necessity" and the conclusion, thereof, that the simplest explanation or strategy tends to be the best one...

Occam's razor states that the explanation of any phenomenon should make as few assumptions as possible, eliminating those that make no difference in the observable predictions of the explanatory hypothesis or theory...

When competing hypotheses are equal in other respects, the principle recommends selection of the hypothesis that introduces the fewest assumptions and postulates the fewest entities while still sufficiently answering the question...

To quote Isaac Newton, "we are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances. Therefore, to the same natural effects we must, so far as possible, assign the same causes."

Occam’s Razor Test:

Plasma Matter – Pass.
Dark Matter – Failed.

Electrical Energy– Pass.
Dark Energy – Failed.

Electromagnetic Fields – Pass.
Black Holes – Failed.

Electric Universe – Pass.
Big Bang Universe – Failed.

Cabal · Dec 1, 2009

Doveaman said:
Occams Razor Facts:

Occam's razor is the principle that "entities must not be multiplied beyond necessity" and the conclusion, thereof, that the simplest explanation or strategy tends to be the best one...

Occam's razor states that the explanation of any phenomenon should make as few assumptions as possible, eliminating those that make no difference in the observable predictions of the explanatory hypothesis or theory...

When competing hypotheses are equal in other respects, the principle recommends selection of the hypothesis that introduces the fewest assumptions and postulates the fewest entities while still sufficiently answering the question...

To quote Isaac Newton, "we are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances. Therefore, to the same natural effects we must, so far as possible, assign the same causes."

Occams Razor Test:

Plasma Matter Pass.
Dark Matter Failed.

Electrical Energy Pass.
Dark Energy Failed.

Electromagnetic Fields Pass.
Black Holes Failed.

Electric Universe Pass.
Big Bang Universe Failed.

Slightly better.

The point is we're going to disagree on this:

"sufficient to explain their appearances"

From when we discussed EU, what struck me most was not your tendency to rubbish the hypothesised explanations like dark matter, energy, etc. but your tendency to rubbish the most basic observations, like CMBR and redshift data. Trying to reduce this to an Occam's razor debate on explanations is, imo, putting your point of view on an equivalent position with Lambda-CDM. If you won't even accept the basic observations, then I think we're going to have much bigger problems to discuss than an Occam knife fight.

And apart from anything else, I'd rather not drag WC's topic off-track.

AV1611VET · Dec 1, 2009

Does England have a king?

If not, will it have one, and who will he be?

Wiccan_Child · Dec 1, 2009

AV1611VET said:
Does England have a king?

No. We have a Queen, and her husband is a Prince (specifically, the Prince Consort).

AV1611VET said:
If not, will it have one, and who will he be?

Well, Prince Charles is the Heir Apparent (i.e., next in line to the throne), so he'll probably be the next Monarch, and, thus, King of England (et al).

Wiccan_Child · Dec 1, 2009

Doveaman said:
Occams Razor Facts:

Occam's razor is the principle that "entities must not be multiplied beyond necessity" and the conclusion, thereof, that the simplest explanation or strategy tends to be the best one...

Occam's razor states that the explanation of any phenomenon should make as few assumptions as possible, eliminating those that make no difference in the observable predictions of the explanatory hypothesis or theory...

When competing hypotheses are equal in other respects, the principle recommends selection of the hypothesis that introduces the fewest assumptions and postulates the fewest entities while still sufficiently answering the question...

To quote Isaac Newton, "we are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances. Therefore, to the same natural effects we must, so far as possible, assign the same causes."

Agreed. But since the modern cosmological model is leaps and bounds ahead of your EU model, they are decidedly not equal, and thus Occam's Razor dose not apply.

Wiccan_Child · Dec 1, 2009

Image of the now:

'Einstein's Cross' is an image of a quasar duplicated around a central galaxy. In reality, the quasar lies behind the galaxy, but the light from the quasar is bent round the galaxy, causing these multiple images to form. This is an example of gravitational lensing.

These are 'Einstein's Rings', another optical phenomena where light from behind a massive object is warped around it due to gravity. Here, the images of galaxies are warped into rings by the galaxies in the foreground.

Cabal · Dec 1, 2009

AV1611VET said:
Does England have a king?

Nope. Queen Elizabeth II's husband is The Duke of Edinburgh, he's not given the title of King - that's only given to the direct male descendants.

I think the various spouses of the monarch take different titles fairly often - and while if the head of state is male he tends to be called King and his wife called Queen, it doesn't seem to be the case the other way round. Queen Victoria's husband was known as Albert, Prince Consort.

(I'm afraid if you're looking for some kind of logical order in events, British history is most definitely NOT the place to look for it )

If not, will it have one, and who will he be?

Next monarch should be Prince Charles, who will be Charles IV.

After that, it should be Prince William, who will be William V.

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