Does a shadow have mass?

Originally posted by Nygdan

Originally posted by SpittinCobra
I think if light has mass the a shadow has mass.

Doode, a shadow is not a thing. Its just a zone where there is less light, usually that which is blocked by some object. The surface its on has mass, the shadow does not have mass. A shadow is not a thing, you can't hold a shadow, its not made up of anything, not even the light that is there. Saying a shadow has mass is the same as saying a room becomes heavier when the lights are turned off.

Ok, but does light have mass?

Are you saing night is the same as a shadow? Not saing I agree or disagree just wondering your view.

Shai

Isn't it conceivable that what we identify as sub-atomic particles possessing no mass but still exerting influence on our reality are nothing more than the 'shadows' from another dimension.

that was a very good point, out of convetional shadow conceps, yes maybe your right, its about virtual particles and the "universe" below quantum limits, actually the uncertanly concepts find some explanation under that "multidimensional universe"

Originally posted by Seapeople
No where will you find conclusive proof that light has mass, therefore, a shadow has no mass being it is a shade of light.

I've read somewhere in a science publication that sunlight is exerting pressure (the photons themselves) on the surface of the Earth at a rate of 6 lbs./mi.^2.

The sunlit side of Earth experiences weight from the sun equal to that of a modern, luxury cruise ship.

If anyone else have heard this or read it, please post.

EDIT; Also, light has been observed as both, waves and particles. If anything larger than a quark exists, then it has mass.

In other words, if it's larger than nothing, then it exists.

A shadow on the other hand is the absence of light, therefore being mass-less itself!





[edit on 25/1/05 by Intelearthling]

light, visible light, visible radiation -- ((physics) electromagnetic radiation that can produce a visual sensation; "the light was filtered through a soft glass window")
=> actinic radiation, actinic ray -- (electromagnetic radiation that can produce photochemical reactions)
www.cogsci.princeton.edu...

So, if light is just a visual sensation created in your brain as a result of electromagnetic radiation, which contains no mass, we can assume that a shadow, which is the absence of light (electromagnetic radiation) can also contain no mass.

.
Solar Sails work on the principle that light striking an object and bouncing off pushes the object.
Some theorize that a perfectly mirrored surface would not be pushed, others disagree.
To push an object, energy must be being released into the struck object.
Can a photon lose enough of its energy to transform into something else? Or would it just be consumed by the Universe and maybe turn into space or something?

A shadow is an area that is not being struck by this photon energy. So it is an absence of something [like zero is an absence of quantity].
Comparitively though a patch of shadow surrounded by a lit region would be an unpushed region in the midst of something(s) being pushed.

I had an odd thought, isn't the Universe made of things that are slower than or equal to light? Perhaps there are a whole set [or at least one] of other realms which are made up of all the things that go faster than light.


Odder thought: Think there might be something called anti-light? That instead of pushing an object pulls an object to it and gains a bit of energy. If you have anti-matter why not anti-forces?
.

Originally posted by WyrdeOne
If a beam of light hits you from behind, some of the light is reflected, some is absorbed, and some passes through you. The same is true of our aptmosphere, and the same is true of our moon, and just about everything else that has mass. If a photonic light packet hits something, it breaks up in accordance with the wavelength that it strikes. Blue light is reflected off of blue cloth in greater quantity, therefore, less blue light gets through blue cloth. As I understand it, this has to do with vibratory sympathy (the commonality in the pattern of atomic movement shared by light waves and any given reflector).

I think the bottom line is, all light is energy, but not all energy is light.

They call gravity the weak force, but I don't think they've accounted for some of the properties of gravity possibly existant in inter-galactic systems. Larger bodies, like galaxies, neutron stars, etc. may trump so called 'strong' forces when it comes to influence, but we don't know. Most scientists will say that galaxies don't come close enough to each other to exert any force, but I can't see how that's possible, unless their field is so repellant that they can't touch.

As far as the human shadow being a reflector of the passage of sub atomic particles, I don't think so. As far as the human shadow being a trail of recently broken light, that's more accurate I think. If you've ever shot a film, you'll know all about diffusion - it's what gets hung over the lights, in varying thicknesses, to soften and spread the illumination. The human body, indeed the human energy field, is a kind of diffusion. We absorb a great deal of light, which gets processed by our mitochondria (I believe) and trapped in our melanin.

Also, I'm not sure our universe is expanding faster. I know the red(?) shift would tend to indicate that, but I don't yet have full confidence in scientific understanding of the properties of the outer edges of the universe. I also don't think we can infer anything about the outer edge of the known universe, certainly not using observable phenomenon to understand the laws in effect. In my mind that's equivalent to observing a tidal pool and formulating theories on the pressure variances at 5000 feet below the sea. Most scientists are confident in their ability to extrapolate successfully, I'm not so positive.

If you want to understand the properties of gravity, the best place to start in my opinion is in fluid dynamics. The similarities are many. I don't think gravity acts on us from another dimension, at least I haven't read anything to indicate that. I think gravity acts in this dimension, perhaps upon other dimensions, but not from them. If you have any links to the contrary I'd love to read them.

Most helpful, thank you..but still not exactly what I'm on about. Perhaps this site will help us get on the same page:
www.bbc.co.uk...

And use this as a background for whatever else we discuss..:
www.science-spirit.org...

Thanking you in advance
-Sincerely
-shai

what about a really fat guys shadow? still no mass?

Originally posted by radagast
a shadow is really more of a perception, imo, caused by a reduction in light by a material object in the path of a light source. I would argue a shadow exists on the back of our retina's and therefore does not have mass.


perhaps you could weigh one ?

I agree with this theory! A shadow only exists in our perception of what we see. There isnt a shadow physically on a wall, that we are looking through to see the darker bricks, the bricks look darker because we are blocking the light to that section of the wall, altering the image. Everything we physically see is reflections of light in different quantities, that are translated to our brains in images. Colors are the amount of light that is diffused by (something- I cant really think of what I am trying to say at this time, but I think you know what I am aiming for) So I think basically by blocking the amount of light an object recieves, we are merely changing its image- which might be why shadows cant be seen through certain types of lenses.

Originally posted by Nygdan
Great babbling baby jesus! What the hell was any of that supposed to mean? I think anyone who has a real concern that shadows might have mass need stay away from superstring theories and m-brane theory and why it requires 11 dimensions.

My take on it is very simple...if other dimensions exist then they are intersecting with us all the time and must have a bearing on our 'reality', an influence.
But how can objects with no mass be subject to gravity?

I posit that [for lack of a better word] what we are defining as subatomic particles or quantum effects could best be understood as the tell-tale shadows of objects or processes occurring in dimensions next to and intersecting ours.
That if we could begin to fathom what dynamics and rules [if any] would apply in other dimensions, that in turn would lead to us understand and predict such results as we are observing in our dimension..
That in fact while we go about discussing the theoretical implications of mass-less photons we should start understanding them as being the outlines in our dimension of what exists in an another..in other words shadows.

It is all a question of light and shadow.

-Sincerely
-shai

Originally posted by SpittinCobra
Ok, but does light have mass?

Its irrelevant to the discussion. But from what I understand, light can impart force, but doesn't have mass, even tho it can be affected by gravity. Eitherway, its irrelevant. If light was as heavy as leady, a shadow wouldn't have any mass.

Are you saing night is the same as a shadow?

Night, darkness, shadow, all the same thing, just to different degrees. When I turn off a light, there is no light. When the sun goes down, there's only a little moonlight. When I block sunlight at, say, sunset, I cast a shadow, that shadow has no substance, its not composed of anything, its just an area on which there is less light than the immeadiately surrounding area, we are seeing a darkened area.

on solar sails, i had thought that they were sailing the solar wind. Apparenlty they arent

solarsails.jpl.nasa.gov...
a solar sail is a giant mirror that reflects sunlight in order to transfer the momentum from light particles (photons) to the object one is interested in propelling.

So that should clear that up.

shai
.if other dimensions exist then they are intersecting with us all the time and must have a bearing on our 'reality', an influence.
But how can objects with no mass be subject to gravity?

I've noticed that people for a while were using 'quantum mechanics' to explain any 'weird' theory they were entertaining, and that now string theory and m-brane theory are filling the same role.
If photons are an effect of an extradimensional phenomenon that has mass, how, in any way, does that mean that shadows could have mass?

I posit that [for lack of a better word] what we are defining as subatomic particles or quantum effects could best be understood as the tell-tale shadows of objects or processes occurring in dimensions next to and intersecting ours

This is kakugo (or some such)'s theory, that gravity is an effect of interacting 'membranes' at a fundamental level.

them as being the outlines in our dimension of what exists in an another..in other words shadows.

IOW you aren't talking about anything like actual real world shadows at all.

Originally posted by Nygdan

They're neither. They are a spot where there is less light, hence they look dark. They have no mass because they aren't anything.

This is enough information to end this discussion. If you missed it I suggest reading the quote above a couple of times. I was intrigued for a couple of seconds though.

Originally posted by slank
.

I had an odd thought, isn't the Universe made of things that are slower than or equal to light? Perhaps there are a whole set [or at least one] of other realms which are made up of all the things that go faster than light.


Odder thought: Think there might be something called anti-light? That instead of pushing an object pulls an object to it and gains a bit of energy. If you have anti-matter why not anti-forces?
.

Funny you should mention that...since anecdotal evidence from sources claiming to have been contacted by off-planet visitors relate that instead of ET's of one stripe or another pushing themselves here they focused on the point they wanted to reach in space and 'pulled it toward them'.

Also..it may go a long way to explaining the ever popular idea that there is a war going on being forces of light and forces of darkness and that, indeed, is the nature of the Universe..
But that is a discussion for a different thread.

So glad to be getting the feedback from all of you..most interesting perspectives in almost every post.

Thanks guys!

-Sincerely
-Shai

Originally posted by Shai
Here is why I pose the question...it seems to me that all this discussion of photons, and other sub-atomic particles possessing mass or negative mass is really a discussion about the mass of shadows.

No. A shadow is the absence of photons. So mass of shadow != mass of photons.

Let me explain...according to my understanding of current theory, we live in a multiverse..and the multiverse is comprised of 11 dimensions.

It is not proven yet.

We know that the basis of everything in the universe is 'light', whetehr visible or invisible..yes?

Absolutely not. What you are saying does not make any sense. The basis of everything is the quarks and the 4 basic forces.

And as I have said in recent posts..[as is born out in super-string theory and zero-point-field theory]

The ZPF is not proven yet. Although it might be something there, provided that the Cassimir effect is real and not an observational error.

that would mean we are constantly being interacted with by other dimensions.

It's only a far fetched theory.

Isn't it conceivable that what we identify as sub-atomic particles possessing no mass but still exerting influence on our reality are nothing more than the 'shadows' from another dimension.

The group of something can be greater than its sum.

In other words, mass may be the result of interaction of foundamental properties, rather a built-in attribute of sub-atomic particles.

it shoots particles into our space and time

Our universe is a closed system. Check out the laws of thermodynamics.

And of course, just like shadows, although we can see them, measure their movement and their area we will never be able to calculate their 'mass',..since they have none. So are shadows illusions or are they indicative of realities beyond our borders...

You did a quantum leap in your thought. You correlated the same word in different context; in other words, you did the following: light shadow = shadowy particles.

There are many logical inconsistencies in your thoughts.

Originally posted by masterp

Originally posted by Shai
Here is why I pose the question...it seems to me that all this discussion of photons, and other sub-atomic particles possessing mass or negative mass is really a discussion about the mass of shadows.

No. A shadow is the absence of photons. So mass of shadow != mass of photons.

Let me explain...according to my understanding of current theory, we live in a multiverse..and the multiverse is comprised of 11 dimensions.

It is not proven yet.

We know that the basis of everything in the universe is 'light', whetehr visible or invisible..yes?

Absolutely not. What you are saying does not make any sense. The basis of everything is the quarks and the 4 basic forces.

And as I have said in recent posts..[as is born out in super-string theory and zero-point-field theory]

The ZPF is not proven yet. Although it might be something there, provided that the Cassimir effect is real and not an observational error.

that would mean we are constantly being interacted with by other dimensions.

It's only a far fetched theory.

Isn't it conceivable that what we identify as sub-atomic particles possessing no mass but still exerting influence on our reality are nothing more than the 'shadows' from another dimension.

The group of something can be greater than its sum.

In other words, mass may be the result of interaction of foundamental properties, rather a built-in attribute of sub-atomic particles.

it shoots particles into our space and time

Our universe is a closed system. Check out the laws of thermodynamics.

And of course, just like shadows, although we can see them, measure their movement and their area we will never be able to calculate their 'mass',..since they have none. So are shadows illusions or are they indicative of realities beyond our borders...

You did a quantum leap in your thought. You correlated the same word in different context; in other words, you did the following: light shadow = shadowy particles.

There are many logical inconsistencies in your thoughts.

I think before you start dismissing my illogical and incionsistent thoughts on the subject that you should catch up with some modern 'science'..Have you heard of Aumic Theory? Or have you not read about quantum physics theory regarding 'virtual particles'as opposed to real particles?
You came very close to supporting me with one point you made and that was your reference to some properties interacting on objects without mass that would cause them to behave as if they did have mass.
Isn't that exactly my point? That it is the properties inherent in a multi-dimensional world which cause the observed phenomena of 'mass-less particles' to be [seemingly] affected by gravity..
www.geocities.com...

I keep referring to the ZPF in posts related to theoretical physics and I sincerely hope you review this site ...
www.calphysics.org...
....before coming at me with your rebuttal.
As you can see, although I am a layman, i am aware of current theories and would like to engage in a 'serious' discussion, even if I can't do the 'math' to support my ideas on the subject.

I leave you with two summaries which should..um..'enlighten'you:
Cosmological ZPE

Recently, ZPE was mentioned in Science (Vol. 282, Dec. 18, 1998, p. 2157) in an article called the "Breakthrough of the Year." Two teams of astronomers have confirmed that distant galaxies are accelerating apart. Furthermore, 2/3 of all astronomers now acknowledge the data as valid. Thus the cosmological constant envisioned by Einstein is being reconsidered and an antigravity force being postulated. Physicists have also interpreted the force as "the evanescent particles that flicker in and out of existence in ‘empty’ space that gives space its springiness, shoving it apart." Scientific American seems to agree ("Cosmological Antigravity", January, 1999, p. 53): "The aggregate energy represented by these ‘virtual’ particles, like other forms of energy, could exert a gravitational force, which could be either attractive or repulsive depending on physical principles that are not yet understood." The cosmological constant represents energy inherent in space itself and coincidentally is almost exactly equal to the average density of ordinary matter in the universe (10-29 gm/cc), at this particular time in its evolution.
[www.zamandayolculuk.com...]

And this one..copied from a site about the new Aumic theory:

“Aumic” theory is not the only theory that states that every point in the Universe is filled with “virtual “ photons. Present day Quantum Field theory also holds that “virtual” photons permeate every part of the Universe . Quantum field theory , however , goes a step further and states that “virtual” photons themselves give rise to electron positron pairs , which since they represent matter and anti-matter collide and annihilate themselves giving rise in this process to a real photon which moves away at the speed of light to be eventually absorbed by an atom . “Aumic” theory states that the Universe is filled with “virtual photons but unlike Quantum Field Theory which states that “virtual” photons are the result of an all pervading electromagnetic radiation , and that these “virtual” photons originate in matter and hence exist throughout the Universe .]

And lastly..I didn't say we were dealing with 'shadowy' characters..i said that trying to measure these partic les is like measuring the mass of shadows.
Shadows are optical illusions..yes?
The observer influences the experiment..yes?
Now follow those to points to their logical extensions and you will arrive smack in the middle of ZPF and Aumic theory.

When you do, come on back and we'll discuss things...yes?

-Sincerely
-Shai

Whether or not light has mass depends on which of two definitions of 'mass' a particular physicist likes to use, and what type of light you're talking about.

One definition of mass says that anything which has some gravitational pull on other objects has mass. By that definition, light has mass. This definition of mass is the same as the definition you get if you ask what 'm' you have to multiply the velocity 'v' by to get the 'momentum' of an object. Momentum is a measure of how much stuff is moving which way. When things bump into each other, the total momentum doesn't change even though it might be traded between the objects. Think of when two balls bounce off each other. Light has momentum, which means we can actually measure the push it gives to objects it runs into. This is the definition used by Einstein, for example in the famous equation E=mc^2.

On the other hand, physicists often find it convenient to think of mass as something that doesn't depend on how an object is moving, also sometimes called the 'rest mass'. They call the mass of some object the mass that it would have according to somebody who says the object isn't moving. Light always is moving, so by this definition (or more careful versions of it) a light ray has no mass.

If you have a box of light, with the rays going every direction, the light does contribute to the total mass of the box, by any definition.

Originally posted by Jadette
One definition of mass says that anything which has some gravitational pull on other objects has mass. By that definition, light has mass.

I have never heard of light having gravitational pull. i've heard of it being affected by gravity, but not 'generating' gravity.

If you have a box of light, with the rays going every direction, the light does contribute to the total mass of the box, by any definition.

By this reasoning then the box is less massive after then lights have been on for a while and then turned off.

Originally posted by Nygdan

Originally posted by Jadette
One definition of mass says that anything which has some gravitational pull on other objects has mass. By that definition, light has mass.

I have never heard of light having gravitational pull. i've heard of it being affected by gravity, but not 'generating' gravity.

If you have a box of light, with the rays going every direction, the light does contribute to the total mass of the box, by any definition.

By this reasoning then the box is less massive after then lights have been on for a while and then turned off.

Yes, perhaps, but what is the mass of Schroedinger's Cat? Don't we have to figure that in somewhere?

Kidding..just kidding.

My point however is that theoreticians seem to talk past each other and are not as keen on melding theories as using one to cnacel out another.
To wit:..if the super-stringers 11 dimensional universe would be accepted..and we were to combine that with the quantum theorist observations of particles springing into being out of thin air [a microcosmic parallel to the original Big bang in which some undefined 'singularity' exploded in a ball of light which then condensed into matter..yad yada]..
well then perhaps we'd have a grander idea of the way things work...these subatomics would not be popping in and out of Existence..just dimensions.

The key, I believe is accounting for gravity..which as one poster put it, is the strongest and weakest of all the forces, one which pervades all dimensions and from outside the universe.
In order for gravity to work it would need a means , a method upon which it could affect óbjects ....a fabric within which these little bits of half-wave/half-particle are contained and can thus be affected.

To me the ZPF is the model which perfectly explains what we are observing..indeed in every dimension one would find gravity and a ZPF.

Einstein's famous equation is not just a one-way proposition..E=MC2 means not only can mass be converted into energy, but that energy can be converted BACK into mass.
And it also means that of light can be affected by gravity, that shadows are equally affected..despite the invisibility factor.
Thinking of dark matter as the shadow being cast by all the stars is an easy way for me to picture the universe as seen by human eyes.


;-)

-Shai

Originally posted by Nygdan

Its irrelevant to the discussion.

I disagree, without light you can not have a shadow. Period.

A shadow unequivocally does not have any mass. Not sure what else I can add to that.

Originally posted by Kriz_4
A shadow unequivocally does not have any mass. Not sure what else I can add to that.

And that sums up my feelings perfectly as well..so instead of measuring the mass of shadows we should be looking for whatever is casting the shadow to measure.
ATTN: all theeeoretical physicists...If it doesn't have mass its an illusion..get it?'

-Sincerely
-Shai