Question Photons

[Bruce B]

How can a lowly photon travel from 13.8 billion light years and reach out telescopes without "dying" in space, since there are atoms and molecules in every cubic meter of space?

 

[billslugg]

There are very few atoms in interstellar space, almost all of them are ionized hydrogen, thus only protons floating around. No photon can be absorbed by a free proton.

 

[Bruce B]

There are very few atoms in interstellar space, almost all of them are ionized hydrogen, thus only protons floating around. No photon can be absorbed by a free proton.

Hi Bill. Thank you for the answer. If that is the case, are there different energies that photons possess from the time they were released, that enables them to travel the vast distances across the universe?

 

[billslugg]

The ability of a photon to travel across the universe is independent of its energy, all photons travel in a vacuum at the speed of light. It is possible for two photons to join together to produce an electron and a positron but their energies must total more than 1.02 MeV and it must occur in the presence of a strong electric field such as a heavy atom such as uranium or lead in order to conserve momentum. It cannot occur in free space.

 

[Jzz]

The ability of a photon to travel across the universe is independent of its energy, all photons travel in a vacuum at the speed of light. It is possible for two photons to join together to produce an electron and a positron but their energies must total more than 1.02 MeV and it must occur in the presence of a strong electric field such as a heavy atom such as uranium or lead in order to conserve momentum. It cannot occur in free space.

Taken in a practical sense the theory that photons travel as independent particles, is too full of unexplained theories that clash with well observed phenomena. Yet amazingly these anomalies are brushed over. Where would we be if this theory of how photons travel, were true? We are already isolated in the Universe, if the quantum mechanics theory of photons and photon travel were true it would mean that it would be impossible to receive radio or light signals from distant sources. There would be no wonderful interstellar transmissions from the Voyager space craft. If it is felt that it necessary to argue about this, get real, given the extreme weakness of the power available for the signal (about 25 W) the photons resulting from such a signal would diverge to such an extent that it would miss earth, if not the solar system by a wide margin. A far more plausible solution is that the signal is travelling through a medium (call it the aether if you like) and spreading out in accordance with the inverse square law. This means every point in the solar system would be covered by the signal.

If you want to learn about how this works. Read my paper; The Electromagnetic Universe :

https://www.academia.edu/37258409/The_Electromagnetic_Universe_docx

If you would like to learn about the theory inn greater depth read the book:

https://www.amazon.com/Electromagnetic-Universe-New-Physics/dp/1695304888/ref=sr_1_2?crid=2XIAOCCYB0DIY&keywords=The+Electromagnetic+Universe&qid=1649488751&sprefix=the+electromagnetic+universe,aps,327&sr=8-2

 

[billslugg]

"...get real, given the extreme weakness of the power available for the signal (about 25 W) the photons resulting from such a signal would diverge to such an extent that it would miss earth, if not the solar system by a wide margin." - Jzz

Here are the facts:
- Distance of Voyager spacecraft - 155.6 AU
- Transmitter strength - 25 watts
- Transmitter frequency - 8 GHz
- Voyager dish antenna beam width - .5°
- Planck's constant = 6.62607015×10−34 J⋅Hz−1
- Signal received by VLA comprised of 27 antennae each 25 m in dia

A 25 watt transmitter emits 25 joules per second.
Each photon at 8 GHz is equal to 8e9 x 6.6e-34 or 5.3e-24 joule
A 25 watt signal thus emits 4.7e24 photons per second
A distance of 155.6 AU is 2.3e13 meters
A .5° beam at that distance has a width of 2e11 meters
At our end, a circle of that width has an area of 3.14e22 m^2

Each square meter of antenna surface, at the distance of Earth thus receives
(4.7e24 s^-1/ 3e22 m^2) = 150 photons per second. A circle of radius 1.8 inches would be required in order to intercept one photon per second.

The signal is received by the VLA with a total area of 13,200 m^2 for a signal strength of 2 million photons per second.

Not only would the signal not miss the Solar System, it would not miss a coffee cup.

 

[Jzz]

Not only would the signal not miss the Solar System, it would not miss a coffee cup.

OK! Calm down. I was thinking more in terms of the geometry than the intensity at the start of the transmission. Given the tiny radius of the source transmission the spread of each individual photon trajectory would be massive at 21 trillion meters distant, and given that the planets are grouped at a maximum of 10 trillion meters around the sun, a miss is a definite possibility.

 

[billslugg]

Yes, a miss by any individual photon is likely. Good thing there are 10^24 per second of them.

 

[Jzz]

Billslugg, I know we have had this discussion before. Let me try a new tack. Imagine a loud speaker and a shot gun, both generate the same amount of power.The shot gun is fired cross the width of a football field. At the same time the speaker is turned on. If there is a crowd of people at the edge of the field a few may feel the impact of the pellets , most won't because the pellets would have lost a lot of their power, but everyone will hear the sound from the speakers.

 

[billslugg]

The air in a football stadium is comprised of something on the order of 10^30 molecules, each one which is shifted back and forth by a sound wave. Billions of them impact every eardrum, thus everyone hears the noise.
A shotgun shell might hold a couple of hundred pellets. By the time they reach the other side of the field they are each several feet apart, not every person will encounter one.
Both methods of energy transport diverge as the square of the distance they must travel, just as radio waves do. If there are not enough carriers then, yes, there is a good chance the receiver might not encounter one. But in the case of Voyager, there are 10^24 being sent towards Earth every second. We have no trouble in intercepting them.

 

[Jzz]

The air in a football stadium is comprised of something on the order of 10^30 molecules, each one which is shifted back and forth by a sound wave. Billions of them impact every eardrum, thus everyone hears the noise.
A shotgun shell might hold a couple of hundred pellets. By the time they reach the other side of the field they are each several feet apart, not every person will encounter one.

This post is not meant to be contentious in any way, it merely illustrates a wish to try to understand the problem better. Just checked your figures and they seem to be approximately accurate. The volume of a football field is approx. 21333.7 cubic yards to the height of the goal posts. 21333.7 cubic yards translates to 1.63 x 10^10 cm ^3. There are approx. 2.7 x 10^19 air molecules in one cm^3 of air so a total of 2.7 x 10^19 x 1.63 x 10^10 = 4.4 x 10^29 molecules of air in the football field (approx..) If the dia of the speaker is 30 cm (1 ft) it will have an area of is 707 cm ^2 approx. This area will impact 707 x 2.7 x 10^19 = 1.9 x 10^22 air molecules. Now take a hypothetical shot gun shell containing 1.9 x 10^22 pellets (approx.) each pellet will be separated from every other pellet by 4.4 x 10^29 / 1.9 x 10^22 = 2.3 x 10^7 cm . (203 km!) Exclamation mark mine. For all I know these figures might be completely off but it does serve to demonstrate the difference between how a wave and a solid object travel.

 

[billslugg]

You cannot take the number of pellets in a stadium (4.4x10^29), divide that by the number of pellets touching a speaker cone (1.9x10^22) and get a distance (210km). You get a dimensionless number which is the number of pellets that got moved by each pellet moved by the speaker cone.

 

[Jzz]

You cannot take the number of pellets in a stadium (4.4x10^29), divide that by the number of pellets touching a speaker cone (1.9x10^22) and get a distance (210km). You get a dimensionless number which is the number of pellets that got moved by each pellet moved by the speaker cone.

Now, surely, we enter the realm of humour. A stadium is not, and can never be filled with shotgun pellets. Although, I get where you are coming from. The fact is, shotgun pellets travel through air (filled with air molecules) and a sound wave also travels through air (filled with air molecules) but the sound wave interacts with all of the air molecules in the stadium while a shot gun pellet goes on its individual way. Therefore the pellet gets separated by a considerable distance from the other pellets it started off with, which were originally in close proximity to it. Therefore, even though the number of air molecules in contact with the speaker diaphragm and the number of pellets in the shotgun shell are the same, the manner in which they travel differs, the shotgun pellets diverge outwards and get separated from their companions while the sound wave manages to convey its energy to all of the air molecules in the stadium. The same would apply if photons were treated as individual particles.

 

[billslugg]

Yes, photons are individual particles. As they travel outwards they get separated from each other. In the case of Voyager I, by the time the cloud of photons reaches the Earth, they are separated from each other by an average of about 2 inches. We are easily able to intercept enough of them to generate a signal in a radio receiver.

 

[Jzz]

Yes, photons are individual particles. As they travel outwards they get separated from each other. In the case of Voyager I, by the time the cloud of photons reaches the Earth, they are separated from each other by an average of about 2 inches. We are easily able to intercept enough of them to generate a signal in a radio receiver.

OK, just to put things in perspective the ray from a pocket laser would be about 13 Km across by the time it reached the moon! Although scientists have been trying to get a reflection back from mirrors placed on the moon, it is only now after 25 years of trying (2020) that they have managed to get a reflection back from a laser. This too is not from a reflector placed on the surface of the moon but from a reflector placed on the lunar orbiter. So¸ it is really a non sequitur to try to equate the manner in which a particle travels with the way in which a wave travels. There is a huge difference. Consider a grain sized particle For instance there about 10^19 molecules in a grain of sand, roughly the same number of molecules that a 30 cm dia speaker would interact with but you cannot expect that grain of sand to interact with all of the molecules in the air, it is not possible even though the number of molecules that the speaker interacts with and the molecules in the grain of sand are the same.

 

[Jzz]

You cannot take the number of pellets in a stadium (4.4x10^29), divide that by the number of pellets touching a speaker cone (1.9x10^22) and get a distance (210km). You get a dimensionless number which is the number of pellets that got moved by each pellet moved by the speaker cone.

In any case you were quite right, I made the mistake of taking the number of molecules of separation as centimetres, the difference would be much less than a centimetre, maybe a thousandth of a centimetre. But, that doesn't mean I am wrong, read the previous post (#15).

 

[billslugg]

The first laser ranging experiments of the Moon were done in 1962 by US scientists at MIT and again by Soviet scientists in the Crimea. In both cases they received photons bounced off the Moon's surface.
Three Apollo flights, 11,14 and 15 left retroreflectors, all of which returned photons. The Soviets left two of them up there, both of which worked. We did it again more recently with the orbiting satellite, LRO.
I am not sure what point you are trying to make, can you summarize it succinctly?

 

[Jzz]

The first laser ranging experiments of the Moon were done in 1962 by US scientists at MIT and again by Soviet scientists in the Crimea. In both cases they received photons bounced off the Moon's surface.

I am only quoting what I have read at multiple sources:

Laser Beams Reflected Between Earth and Moon Boost Science

After launching laser beams for years to NASA's Moon orbiter, scientists receive signal back for the first time.

www.nasa.gov

 

[billslugg]

They received a signal back for the first time from the tiny paperback sized retroreflector on the LRO satellite. They have been getting signals back from the suitcase sized Apollo retroreflectors since 1969. The article you are quoting refers to the Apollo retroreflectors saying that the signals are getting weaker. This is because of dust buildup.
I still don't understand what your problem is with photons.

Here is your theory as laid out in post #5:

"Taken in a practical sense the theory that photons travel as independent particles, is too full of unexplained theories that clash with well observed phenomena. Yet amazingly these anomalies are brushed over. Where would we be if this theory of how photons travel, were true? We are already isolated in the Universe, if the quantum mechanics theory of photons and photon travel were true it would mean that it would be impossible to receive radio or light signals from distant sources. There would be no wonderful interstellar transmissions from the Voyager space craft. If it is felt that it necessary to argue about this, get real, given the extreme weakness of the power available for the signal (about 25 W) the photons resulting from such a signal would diverge to such an extent that it would miss earth, if not the solar system by a wide margin. A far more plausible solution is that the signal is travelling through a medium (call it the aether if you like) and spreading out in accordance with the inverse square law. This means every point in the solar system would be covered by the signal."

I proved you wrong in post #6, showing that the sheer number of individual photons was sufficient to send a signal across the Solar System. There is no need for an aether with waves to cover our antennas at that distance. Why cannot you accept the quantum mechanical photon theory?

 

[Catastrophe]

Bruce B,

Now ask a difficult question . . . . . .

Cat