What Is Light?

reply to post by ErosA433


To get back to the question you asked me "why cant there be nothing?"

going off the big bang model of the creation of the universe.... space is ignored before the beginning of the universe...I think, its thought to be impossible to know whats outside the universe so its ignored in the theory..
with that being said, its thought that anything outside of the universe, did not have anything to do with the infinitely dense pre bigbang (all the energy of the current universe) state of the universe... it is thought all points in the universe (quanta of energy/matter and space-time) were contained in the single point... so when inflation and expansion began.. the space-time we see now between galaxies and solar systems, and the space-time that began existing then, is a direct result of the dense state of all energy/matter separating from itself (decompressing).. I think its thought nothingness does not exist in the universe, because the universe is thought to be a closed system, in the big bang theory at least with spatial expansion.. its not thought that objects flow through a nothing ness of background space,, but when they move ( im not that well versed but maybe its called stress energy tensor... like einsteins space-time fabric) they are moving space with it.... Its pretty much describing the universe in a way that the space we know of, is an extension of the matter/energy/quanta we know of and vice versa ( i think)... also this is how einstein explained gravity at all,, by suggesting the notion that space is not nothing, but a something, which can be affected by mass... I think this is potentially the right way to look at the universe (meaning potentially the way the universe actually is) and may help us better comprehend what dark matter may be, and dark energy... Also do you know much about the cosmological constant? I think it is a relatively small factor, but does it refer to non baryonic energy stored in the vacuum? or just accounts for random loose atoms and particles that are not associated with galaxies in intergalactic space?

It is as you all know the opposite of dark. Thought you all knew that.

reply to post by ImaFungi


Got me on that one, though I was really kind of thinking, fields aside, there can exist nothing. And you are on the numbers in that at least in theory the universe is an expansion OF space rather than an expansion IN space. This is something that people get rather confused about normally as they imagine that all of space existed and the big bang was some kind of explosion in the middle.

What is on the outside is one of those big question marks that is quite abstract.

Back at that time what would have first existed as you point out is essentially an extreme density of states, the universe went from energy dominated to matter dominated as it expanded and cooled. All the energy as you say compressed into a singularity, this is a pretty amazing concept and one that is not without its problems. That said, there are examples of how such compressed states exist in the universe today. These objects are difficult to really imagine also. White dwarfs and neutron stars being examples of objects held up by degeneracy pressure. Back in the early universe the energy would mostly be in the form of electromagnetic radiation which would then begin to pair produce heavy quarks/gluons etc which subsequently decay down to form the bottom stable generations. It is why sometimes in the media we say we are trying to recreate the big bang at particle accelerators, because what we are trying to do is recreate that high energy environment.

Not sure if that provides any answers, just thought id ramble a little bit, sorry

[edit]
The cosmological constant is a little bit of a mystery, it seems to represent an energy density of empty space. So my understanding would be an energy inherent within the fields that exist in free space. I aways kind of emagine space as being fields, a mix of EM and G, that the gravitational field is only directly coupled to mass, and electromagnetic coupled to charge, and that the fields may fluctuate in density locally based on the uncertainty principle.

It is probably exactly where a lot of the 'zero point energy' -ers come from. Saying Oh there is alot of stored energy in empty space, we can harness it. Well I agree that the actual zero energy configuration... ground state of space itself is unknown, there are many good reasons why it cant really be harnessed... though as my udnerstanding of the cosmological constant is, it to me is a measure of this.

reply to post by ErosA433


Hmm.. Well I wonder if gravity can be used to harness energy in some way... Also I wonder if dark energy is fluctuations in gravity fields... or is dark energy thought to be the relativistic mass or kinetic energy of galaxies? We take a snap shot of a galaxy and say, hey there should be more mass there, so dark energy is invented, but really that galaxy is progressing through space and time and the material mass we view in the snapshot also has the relative mass (from mass energy equivalent) from its momentum... or do you think the kinetic energy of a galaxy is considered when viewing its material mass, and there is still need for 'dark energy' to explain things about it?

What do you know about the CMB? Why is it thought that is proof of big bang? Do celestial bodies and galaxies no longer emit microwaves? (couldnt it be evidence for lots of alien fast food chains?jk)

also back to the idea of nothing... its a very frustrating one... think about the air around you....every single point is tiny invisible ball like atoms, which you have depending on inhaling your whole life..is there any 'space' between them? so there are quadrillions of this air gas touching your body at all times ( akin to a fish in water) and you are displacing it... if you move fast enough, or just move your hand through the air can you ever touch 'nothing'? i guess this is the idea of a vacuum, but then i must ask, what the heck is a vacuum... is a vacuum like our bodies (in that they displace air)? or vacuum actually contains nothing? is this nothing then a tight stretching of space-time itself, like a vacuum is a large planck scale? idk...weird stuff if you ask me

The CMB is relic radiation from the big bang. The idea is that when the universe became transparent, it had expanded enough such that the radiation length in space became larger than the mean separation between matter particles (or something along those lines) some of these gammas just carry on traveling. In the subsiquent 13 or so billion years as space expands, the doppler effect red shifts these photons right down to the microwave region.

Part of the evidence that these are relics of a hot big bang is that they have a perfect black body spectrum.

en.wikipedia.org...:Cmbr.svg

Also, the anisotropy, ie the measure of how different parts of the sky look are extremely small, which suggests that all parts of the sky were once causally locked to each other. What parts of the CMB we do see in fluctuations would appear to be regions where the first galaxies started to form. It is difficult to think of a mechanism that will produce a perfect blackbody spectrum, all over the sky in any other way. There might be some ideas, but i don't think many of them hold up too well.


Yeah the whole idae of vacuum being different to there being nothing is quite a frustrating one i agree.

reply to post by ErosA433


cool thanks...

Are microwaves emitted from galaxies and stars at all?

Originally posted by wlasikiewicz
Light is something that can be seen but not felt, light has no heat properties what so ever unless you add them with some kind of filament.

Light is lighter than air (excuse the pun) and is the fastest element known to man. Without light humans wouldn't be able to exsist on this earth. Without light food would not grow, trees would not grow (no oxygen)

Even darkness is a form of light, its just black light.

I'm certain that light is just motion. Change. Time. If he proposes light as connection thats just another way of looking at it. Connect two points for a line. Line is perceived as motion or movement. Light is just moving at different scales of time and generating various levels and states of awareness individualized to the speed of its movement.

Originally posted by HumbleHelper
I'm certain that light is just motion. Change. Time.

Motion, change and time are three very different concepts. They maybe locked into another construct in a way that makes them related, but the way you present it here it's just word soup.

Connect two points for a line. Line is perceived as motion or movement.

Why and by whom?

Light is just moving at different scales of time

What specific scales?

and generating various levels and states of awareness

...in who?

individualized to the speed of its movement.

So is it variable?

Originally posted by HumbleHelper
I'm certain that light is just motion. Change. Time.

I'm not a scientist, but I found this thread interesting and have an own idea about that question:

Could it be that light is matter in motion or mass in motion (at the speed of light). When thinking about relativity, isn't it so that - theoretically - the mass of an object moving at the speed of light is indefinite? So it actually 'becomes' light itself. If so, wouldn't it perhaps be possible to reverse the process and extract certain amounts of mass from light by slowing it down in some way (don't ask me how, though)?

It's just a thought. If you think this is total nonsense, please feel free to ignore this post ...

Originally posted by jeep3r

Originally posted by HumbleHelper
I'm certain that light is just motion. Change. Time.

I'm not a scientist, but I found this thread interesting and have an own idea about that question:

Could it be that light is matter in motion or mass in motion (at the speed of light). When thinking about relativity, isn't it so that - theoretically - the mass of an object moving at the speed of light is indefinite? So it actually 'becomes' light itself. If so, wouldn't it perhaps be possible to reverse the process and extract certain amounts of mass from light by slowing it down in some way (don't ask me how, though)?

It's just a thought. If you think this is total nonsense, please feel free to ignore this post ...

Its thought that light is massless, because it is the quantity of energy that can travel with the highest velocity, a constant, the speed of light. Because E=mc^2 .... the energy of light, can be used to push a solar sail and make a space ship with one travel very high speeds. Because the sun emits a lot of light. This light has velocity and momentum, which it imparts as a force on whatever it comes in contact with. So traveling through a vacuum, light is massless, its not affected by gravity like a bowling ball is ( it is thought to be affected by gravity for another reason) but once the massless light touches something like a leaf of a tree it imparts its velocity and frequency, its energy content onto the atoms of that leaf, which the leaf can then qucikly use this EM vibration to store in its mechanisms to use for chemical energy (photosynthesis).

you say light is thought to be matter in motion. The word matter is a little weird, so im not sure, I have a lot of questions about this subject my self, and the words are weird... Because I suppose someone would say light is not matter it is energy. An atom is matter, and it has a total mass from its components, but an atom moving can be considered energy. I think maybe light is considered to be massless because it doesnt exist, or is not known as to where it exists in its rest state, maybe being a phenomenon only of velocity and momentum and interaction, that only exists in certain circumstances. Im not sure. So 5 atoms at absolute zero arent moving,and there for arent emitting light, there is matter there, but not kinetic energy. once we allow the temperature to rise a little (motion between atoms) this is more energy, now they are emitting this light energy and thermal radiation, and it is the same quantity of matter, just in a different circumstance in which they are able to interact in a way as to produce this massless energy we know as light or EM radiation.

You can look for experiments, I think scientists have slowed down light. light can also be slowed through certain mediums, because its said the speed of light is constant in a vacuum. So if we use anything other then a vacuum to slow the light down, we are slowing it down by having the energy interact with atoms, which would be minimizing the quantity of light over a time, which is equal to say the quantity of light that went in our experiment and medium to attempt to slow down is losing energy. and it is transferring its energy to the atoms, im pretty sure this occurs via electron excitation. and so those atoms that receive energy from the light perhaps are momentarily more massive, im not sure exactly.. because I dont know how long atoms which receive light , i dont know how long their electrons get excited, or if there is an extra electron. if the electron "jumps to a higher energy state" without increasing the quantity of electrons in an atom, im not sure if this is still increasing the mass of the atom, but it might be able to be looked at this way, because if the electron jumps to a higher energy state when it is excited with light, then I wonder if that truly means that the atoms total potential energy increases.. and if that is true that an atom has this potential energy... a light quantity hits the atom... now that atom has this higher amount of energy... the higher energy atom because of mass energy equivalence could, I think be said to be more massive. thus you would have turned light into mass, or matter..

Did anyone ever notice that pure energy creates light. Yes if you actually look at an electrical wave between 2 poles you will see a vibrating electrical current that is producing light and sound.

You can also observe this when creating sparks. Sparks create light. Light is nothing more then energy. A vibrating electrical current created by either artificial or biological magnetic poles.

Originally posted by Vicarious10000
Did anyone ever notice that pure energy creates light. Yes if you actually look at an electrical wave between 2 poles you will see a vibrating electrical current that is producing light and sound.

Ok, this is interesting. so there needs to be a source of energy which causes the electrical wave to exist right? What is this example you are describing with 2 poles? are you talking about some type of circuit through air between two poles, or static electricity or something? sorry i trying to think about what you said.

You can also observe this when creating sparks. Sparks create light. Light is nothing more then energy. A vibrating electrical current created by either artificial or biological magnetic poles.

Ok yes, now I see what you are saying. Because of the electric/magnetic (electromagnetic) nature of atoms, the movement of these atoms relative to one another is a form of energy. When these atoms are moved at a certain burst of accelerated rate they produce energetic waves of electromagnetic energy that our eyes are designed to detect, and this is light.

It is interested the wavelength of visible lights place.. do shadows objectively exist? is there such thing as brightness? Because there is a tremendously large scope of wavelengths that atomic EM interaction takes place on..


So why dont we see all the other forms of EM radiation as brightness on the earth, and is the visible light we do see as brightness, is that really "bright", or is it just a mind trick? thats a question id like to ask.

also maybe dark matter, is clumps of structures made of anti matter.. and maybe anti matter doesnt react with em radiation the same.. or maybe dark matter is made of structures of matter that does not contain electrons..
^ im pretty sure both those ideas are wrong, but just tryna think.


Ok well I think shadows do objectively exist, because that is matter, absorbing all visible light before it hits the ground (or something behind a material object)... and thats pretty much the nature of the different wavelengths in general I guess. different atoms and different molecules interact with each wavelength different ways.. I wonder if radio waves (for a radio station) are able to be sent such relatively large distances through the medium of air, because the way in which each atom responds to the intricate signal placed in a radio wave is to perfectly pass it on, like a game of telephone where each atom is completely honest?