[neutralino]

Originally Posted by MJA Thanks again RP, I find this line of thought wonderful! I am somewhat well read in the thought processes of A Einstein, but have never grasped with simplicity the purpose of squared in the equations of physics. Would you do me a great favor and try to explain C squared. I know you know. Thanks, = MJA

A simple answer is that c^2 is a conversion factor. The equation E=mc^2 says that energy is directly proportional to mass, the constant of proportionality being c^2. That is, the c^2 converts from units of mass to units of energy. As I've said here before, one can select units in which c=1 (in fact, these units are utilised quite frequently in relativity and are called geometric units), then the equation reads E=m.

The statement that RascallPuff makes above, in discussing the area of a circle as pi r^2 is not the same; namely in this case, r is a variable: the size of the circle, whereas above, c is a fundamental constant.

[RascalPuff]

Thank you, neutralino. I think I just learned something about pi r squared (in a static context).

Best regards,
- RP

[MJA]

OK physics boys; I sincerely appreciate your help with this question of squared,but must query further as usual.
Light from a star is just like an expanding sphere of energy, isn't it?
Star light is not a narrow beam like a laser as it appears to us, but rather is the same as our sun. Light is emitted from infinite points in infinite directions.
I believe the speed of a light beam can be denoted as C, but should the speed of light from a star be measured like an expanding sphere instead?
Should star light be measure pi r C squared instead?
And while we are on the subject of star light, how is it that the sun emits star light, yet at the same time gravitationally attracts (as has been measured) the star light passing by from a distant star?
If C is C then how can the sun expel and attract light of equal energy or inertia at the same time?
And furthermore, I can understand the potential of bending a beam of light, but can not fathom bending light if it were a sphere of energy as the light of a star is.
If the sun's gravity changes the direction of a photon of light coming from a star, it would have an equal effect on the rest.
It would be observationally impossible to measure a change of direction of a sphere of light, when at the same time surrounded by it.
Even though it appears to us as a beam of light being attracted by the sun during a solar eclipse, it’s really is not, is it?
The stuff we mess with!

Thanks,
=
MJA

[RascalPuff]

OK physics boys; I sincerely appreciate your help with this question of squared,but must query further as usual.
Light from a star is just like an expanding sphere of energy, isn't it?

Not only is it 'like' an expanding sphere of energy, it is that.


Star light is not a narrow beam like a laser as it appears to us, but rather is the same as our sun. Light is emitted from infinite points in infinite directions.
I believe the speed of a light beam can be denoted as C, but should the speed of light from a star be measured like an expanding sphere instead?

Certainly it can be appropriately measured that way. The sun's 'surface', (translatable as an 'event horizon') 'begins', at the parameter of the first light it omnidirectionally projected...


Should star light be measure pi r C squared instead?

No mathematician here, but that may be an alternative standard. I don't see why not.


And while we are on the subject of star light, how is it that the sun emits star light, yet at the same time gravitationally attracts (as has been measured) the star light passing by from a distant star?
If C is C then how can the sun expel and attract light of equal energy or inertia at the same time?

That seems to be one of the cardinal mysteries of gravity, MJA.

And furthermore, I can understand the potential of bending a beam of light, but can not fathom bending light if it were a sphere of energy as the light of a star is.
If the sun's gravity changes the direction of a photon of light coming from a star, it would have an equal effect on the rest.
It would be observationally impossible to measure a change of direction of a sphere of light, when at the same time surrounded by it.
Even though it appears to us as a beam of light being attracted by the sun during a solar eclipse, it’s really is not, is it?
The stuff we mess with!

Well, MJA, there's extant controversy orbiting these issues as you interestingly and cogently present them. Maybe neutralino or someone else can further *field these subjections (*Hee haw) - thought stimulating stuff (A can of wormholes?).



Best regards,
- RP

[r.p.bibra]

Very interesting MJA!regards.ls

[Graybeard]

Originally Posted by MJA Light from a star is just like an expanding sphere of energy, isn't it? Star light is not a narrow beam like a laser as it appears to us, but rather is the same as our sun. Light is emitted from infinite points in infinite directions.

Our Sun is a Star

Originally Posted by MJA I believe the speed of a light beam can be denoted as C, but should the speed of light from a star be measured like an expanding sphere instead. Should star light be measure pi r C squared instead?

What you are trying to measure here is a quantity of light, not the speed.

Originally Posted by MJA And while we are on the subject of star light, how is it that the sun emits star light, yet at the same time gravitationally attracts (as has been measured) the star light passing by from a distant star. If C is C then how can the sun expel and attract light of equal energy or inertia at the same time?

It simply appears that the light from the distant star takes longer to reach us, the observers. When you say 'as has been measured' this is what it means. You are not thinking in terms of SpaceTime .. only of space. Light that takes 'longer' to reach us appears to have come from a different location in the past!

Originally Posted by MJA And furthermore, I can understand the potential of bending a beam of light, but can not fathom bending light if it were a sphere of energy as the light of a star is. If the sun's gravity changes the direction of a photon of light coming from a star, it would have an equal effect on the rest. It would be observationally impossible to measure a change of direction of a sphere of light, when at the same time surrounded by it. Even though it appears to us as a beam of light being attracted by the sun during a solar eclipse, it’s really is not, is it? The stuff we mess with!

MJA ... This doesn't really make a lot of sense ... especially the solar eclipse bit ? If you give yourself a basic understanding of relativity, independent of whether you choose to accept it or not, we would be able to converse a lot easier. I have a really good link for relativity, but not on this computer ... If you think you are interested reply and I will look it up and post it.

Hope I helped and didn't add to the confusion.

cool bananas ... greg

[MJA]

Hi Greg,

I think you miss understood my questions, so let me try to simplify my query for you.
In 1919 a scientist named Eddington went to a place called Principe to measure the passing star light deflection caused by the gravitation of the sun. Because of this measured defection seen during a solar eclipse, Einstein's General Relativity Theory was proved correct.
My questions are in regard to that experiment.
How can the sun radiate light from itself and at the same time gravitate light from a distant star when all light is of a constant energy or velocity of C?
Perhaps C is not so certain as we are lead to believe. And, perhaps the flaw is measure?
Does the energy of light = mass times the constant speed of light in a vacuum squared?
What is the mass or weight of light, of a photon, of a quanta?
And if you can't measure the mass of one photon, how much mass is in a room full of light?
Do you have to stop it to measure it, and will that change it?
Is that like Heisenberg’s Uncertainty Theory?
Conversely, how would you measure a photon at the speed of light?
What does a photon look like?
Can you draw one for me?
How big is a particle of light?
Are you sure we can measure the speed without knowing what light simply is?
How do you measure the speed of star light?
How do we know that all star light is the same, or of a constant propagation?
Have we measured every star in the universe?
The problem Greg, is I really don't believe that the before mentioned experiment has any validity at all, do you?
And I am having the same trouble with C.

Thanks Greg, I hope that helps,

=
MJA

Obviously, the sun is a star, but surely like planets, not all stars and perhaps not all light is the same.

[neutralino]

Originally Posted by MJA Hi Greg, I think you miss understood my questions, so let me try to simplify my query for you. In 1919 a scientist named Eddington went to a place called Principe to measure the passing star light deflection caused by the gravitation of the sun. Because of this measured defection seen during a solar eclipse, Einstein's General Relativity Theory was proved correct.

Well, I wouldn't say GR was proven but yes, GR predicted the gravitational bending of light.

My questions are in regard to that experiment. How can the sun radiate light from itself and at the same time gravitate light from a distant star when all light is of a constant energy or velocity of C?

Firstly, the sun can bend light, since it is not only made up of light; it is a massive body. Secondly, light does not have constant energy. It has energy that is proportional to its frequency. You may be confused and trying to use E=mc^2; but this equation does not hold for light.

Perhaps C is not so certain as we are lead to believe. And, perhaps the flaw is measure? Does the energy of light = mass times the constant speed of light in a vacuum squared?

No; see above.

What is the mass or weight of light, of a photon, of a quanta?

A photon has zero rest mass.

And if you can't measure the mass of one photon, how much mass is in a room full of light? Do you have to stop it to measure it, and will that change it?

This is impossible: a photon always travels at the speed of light.

[Graybeard]

Originally Posted by MJA Hi Greg, I think you miss understood my questions, so let me try to simplify my query for you. In 1919 a scientist named Eddington went to a place called Principe to measure the passing star light deflection caused by the gravitation of the sun. Because of this measured defection seen during a solar eclipse, Einstein's General Relativity Theory was proved correct. My questions are in regard to that experiment.

Yes .. this is correct ... but the reason he did it during the solar eclipse was so those stars would be visible while the sun was hidden ... the eclipse has nothing to do with the experiment

Originally Posted by MJA How can the sun radiate light from itself and at the same time gravitate light from a distant star when all light is of a constant energy or velocity of C? Perhaps C is not so certain as we are lead to believe. And, perhaps the flaw is measure?

In the centre of the sun or any other similar sized star is a massive nuclear fusion process going on. A particle/wave in the midst of this receives enough energy to work its way to the outer crust of the sun . This takes anywhere from 2 to 5 million years for the average particle depending on its energy, freed at last from the massive density it then zips across the solar system between the sun and earth in 9 minutes, strikes a grape vine leaf, and is absorbed in a photosynthetic reaction .. its energy is stored as sugar in the grape. The grape is fermented and the wine is matured for 25 years. When you drink wine you are drinking the energy that started out millions of years ago in the fusion of the suns engine.

But that energy already existed in another form before the sun was even born!

The sun is radiating matter, when the solar particle strikes the grape vine leaf a photon (in the green wavelength) is given off and strikes your eye. If you look at the sun the solar particles will fry the photo-electric cells in your eyes because they are so delicate ... your skin takes a little longer before also burning in the relentless bombardment.

Originally Posted by MJA Does the energy of light = mass times the constant speed of light in a vacuum squared?

I think you mean E=MC^2. This describes the amount of energy that can be contained/released in matter.

If you accept that energy can be converted to matter and matter can be converted to energy then this formula tells you the conversion rate ... just like changing yankee dollars to aussie dollars. You can very easily see that a small amount of matter is capable of a humungous energy release because to get the amount of energy you multiply your gram of matter by 300,000,000 metres per second squared.

Originally Posted by MJA What is the mass or weight of light, of a photon, of a quanta?

I don't know. But recent experiments suggest that photons when they strike an object apply pressure. Future space engines may come from this field.

Originally Posted by MJA And if you can't measure the mass of one photon, how much mass is in a room full of light? Do you have to stop it to measure it, and will that change it?

If you were a lighting engineer and you had to light the Gabba stadium or the Yankee Stadium the units of light you would have to achieve on the field would be quoted in the functional specification as Lux per square metre. If you have a camera with a light meter in it, its is measuring in Lux.

Originally Posted by MJA Is that like Heisenberg’s Uncertainty Theory? Conversely, how would you measure a photon at the speed of light? What does a photon look like? Can you draw one for me? How big is a particle of light? Are you sure we can measure the speed without knowing what light simply is?

MJA ... I think you are being deliberatly provocative here ... or else you have not appreciated the fundamental difference between Quantum Mechanics and Classical Physics ?

Originally Posted by MJA How do you measure the speed of star light?

All light from whatever cause is the same ???