Photons (or, como doesn't understand quantum science)

[Ellie]

A star is shooting out photons.

They go in lots of random directions.

There are many of them, millions, billions, basically a lot.

There may well be enough to create a seemingly unbroken screen of light:

But if we zoom in, or go far, far away down the lines, we see there are gaps between them which get exponentially wider.

If a planet was far enough away it could at any one moment get no light at all, or perhaps one or two photons, from this star.

Is this assumption correct?

I assume there cannot be an infinite number of protons emitted, because infinity isn't a concept science generally likes. But then this is particle physics verging on the quantum and things get a bit different.

No matter how many photons, unless infinite, there have to be gaps. Unless the photons are not particles, of course. (If we placed a particle collector on this far away planet in fig. 3, we would presumably see a lot of areas where no photons hit, however. Is this right?).

 

[Necrile]

To add to this question, since photons should keep moving until it hits something, shouldn't every area of space be lit, except for black holes?

Also how is it a sine wave and a packet of light?

 

[Ellie]

Also how is it a sine wave and a packet of light?

From my understanding it is neither, it just responds as a wave or particle would to their respective tests.

 

[dadevvtsvre]

Okay we just learned about photonstuff in chemistry last week! Going with a basic high school understanding here but here goes.

Photons are interesting. They're classified as elementary particles (meaning they can't be broken up into smaller bits like atoms or protons) yet have no mass, and have been shown to act both like particles and like waves. (double-slit experiment) This is pretty much unlike anything else ever, and we still don't really know why this happens. So yeah, they're technically particles, but they have properties of waves as well.

Here's a basic rundown of how photons work: Light is emitted by light-emitting things (stars, fire, light bulbs, etc) in 'pulses'. It's not a continuous stream of photons and energy being released; rather, it's like a strobe light in the way these things emit light. Except the strobe light is blinking so incredibly fast that our eyes perceive it as a continuous stream of light.

There aren't really straight beams of light being emitted from stars and light bulbs and stuff. You can't *really* zoom in and pick apart one stream of photons, another one here, etc. (really is in asterisks because this is purely theoretical, i'm assuming nobody's ever done this) Light is radiated equally from every direction possible. The black lines on your drawings would not exist, a better drawing would be one continuous sheet of black extending in all directions forever and ever. But if you were standing 10 feet in front of a light bulb it would be noticeably brighter than if you stood 100 feet away. Why?

Imagine yourself inflating a balloon. When you first start the balloon is very small and the skin is fairly thick. Imagine the skin of the balloon is all light, being emitted from a source in the center. As the balloon grows bigger and bigger the surface area of the balloon expands. There is still a uniform covering here - there are no gaps or holes on the balloon - but the skin is getting tighter and thinner. Light does the same thing - its concentration gets less and less as it travels farther and farther from its source. It's important to remember that no energy is being lost here, just like how no rubber goes away when you blow up the balloon, it's just that the concentration of energy is less.

Same goes for planets. Pluto receives less light from the sun than Earth, and Xyrbilljky 1 000 000 light years away receives so little light it's negligible. But basically what's happening here isn't that there aren't photons hitting Xyrbilljky, it's just that the light from our sun has been stretched so thin you can't tell it's there. If light worked the way your drawings depict it then how could we see anything in the sky at night?

Somebody more qualified could probably give a better answer but that's all I got. Sorry if it's a little confusing vOv

 

[Anski]

In theory, they could continue on and a planet could avoid it altogether. This is the case with many stars in foreign galaxies in which they are emitting the same amount of photons but they aren't touching earth, or even our system, due to the sheer space and, as you said, exponential growth. Also, to answer the second question, most of space is theoretically 'lit' in the sense that there are photons of light moving through it, but they are so thin from the distance and bouncing off of others that we can't visibly perceive it. It goes on to say that nobody's really sure what happens to the photons in the end were they to not hit anything. However, a lot of them hit OTHER photons and end up going their own way.

(photons)

 

[Toams]

(photons)

 

[Juan J. Sánchez]

Photons do have mass.

 

[Necrile]

Photons travel at lightspeed. Mass at lightspeed = infinite density. Photons do not have infinite density. Therefore, photons do NOT have mass.

 

[dadevvtsvre]

Photons do have mass.

since when? :p

 

[Juan J. Sánchez]

Well, think of the following: if a photon has energy, which it does, and energy is equivalent to mass, which it is, then a photon has mass. It has been theorized to have no mass because of stupid quantum mechanics and electromagnetic theory (we hate you, Einstein). This has never been proven. Who the heck knows.

 

[Necrile]

Ahem...nothing with mass can travel the speed light. Idk who gave you that bogus education but I'd go get your money back. And energy is only equivalent to mass in the fact that energy is the building blocks to mass (string theory and the such). In the same way, bricks make a house but AREN'T a house. Mass can never travel the speed of light because the speed of light has no mass, and any mass reaching the speed of light becomes more dense. The speed of light is the fastest thing that travels for a reason. It HAS no mass, so it experiences no distortions of velocity and thus never slows (except for some bullshit about space jumps, where in some instances space actually creates a "hole" if you will to jump great distances while retaining the same speed). That being said, this is all theoritical and could prove to be total bullshit in the future.

 

[Juan J. Sánchez]

I believe this link validates my point.

http://www.physlink.com/education/askexperts/ae180.cfm

Also, I'd suggest Como reads it, because it also answers his/her question.

 

[Juan J. Sánchez]

The mass of a particle which travels with a velocity v is given by the following equation:

where m0 is the rest mass of the particle, v its velocity and c the speed of light. It may appear that because photons have zero rest mass (m0=0), their mass is zero too. A closer look at the equation will show that this is not the case because photons travel with the velocity c and the equation collapses to an undefined form (m=0/0) The conclusion is that this equation applies only to sub-lightspeed particles and NOT to photons. But relativity also tells us that every particle with mass m is equal to an energy E given by the famous equation:

E=mc2

where m the mass of the particle, c the speed of light and E the energy that equals to the mass m. This equation also works backwards.An amount of energy E equals to a mass m. Photons however may not have rest mass, but they DO have energy. The energy of a photon is given by the equation:

E=hf

where h is a constant (Planck's constant) and f the frequency of the photon (don't forget that the photon is an electromagnetic WAVE and has a frequency). If we combine these two equations, we come up with the following,which gives us the mass of a photon

mc2 = hf => m=hf/c2

which means that though photons don't have rest mass, they do have energy and thus they have mass. The photons are wave particles. This means that they act as waves and as particles as well. This is the duality of the nature of light (and of every particles). And so as particles they have mass, and as waves they have frequency. The pressure they exert is due to the particle nature of light. It's easy now to understand the mechanism that causes this pressure.

 

[Juan J. Sánchez]

You know what, this is exactly why I'm not studying to be an engineer anymore. I'll just stick with medicine. I hate math.

 

[Necrile]

Figuring out circuits is fun as shit. Medicine is too much studying and situational bullshit.