# Thread: Physics of Solar Sails

1. ## Physics of Solar Sails

https://en.wikipedia.org/wiki/Solar_sail

Solar sails (also called light sails or photon sails) are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large mirrors. A number of spaceflight missions to test solar propulsion and navigation have been proposed since the 1980s. The first spacecraft to make use of the technology was IKAROS, launched in 2010.
The momentum of a photon or an entire flux is given by Einstein's relation:[14][15]

p = E/c
where p is the momentum, E is the energy (of the photon or flux), and c is the speed of light. Specifically the momentum of a photon depends on its wavelength p = h/λ

Radiation pressure is the mechanical pressure exerted upon any surface due to the exchange of momentum between the object and the electromagnetic field. This includes the momentum of light or electromagnetic radiation of any wavelength which is absorbed, reflected, or otherwise emitted (e.g. black-body radiation) by matter on any scale (from macroscopic objects to dust particles to gas molecules).[1][2][3] The associated force is called the radiation pressure force, or sometimes just the force of light.

Here is where things don't seem to add up

Basically, a photon has momentum. If it is reflected by a mirror, then its momentum is reversed. (See diagram above) As momentum must be conserved, the mirror has absorbed twice the momentum of the photon (Photon incident-ed normal i.e. perpendicular to the mirror in my explanation)

But how can it gain momentum when energy must be conserved.

Imagine a perfect reflective mirror. When light is reflected, no photons are loss. And we have never observed a red shifted mirrored image. That is, you look the same color as your reflection. Thus for ideal case, no energy is loss by the photons, so the mirror should never gain energy. However, I do agree that momentum is conserved. I do not know how to explain this phenomena. Perhaps a type of mass-less momentum artifact is passed through the mirror. Perhaps the mirror does move slightly, and in such a slight red shift in the reflected image occurs (for a free mirror). In any case, the current math to explain this does not completely add up

The radiation pressure phenomena does exist though. Einstein has done some work on it (Photo-electric effect) Also in e=mc˛, he used a though experiment where the photon was fully emitted from one side of a box and fully absorbed by the other. I think a greater momentum transfer occurs when the photon is completely absorbed by a dark material as opposed to a reflective material. And when light passes though something "thick" permittivity-wise like glass or even diamond, the diamond gets the momentum of the photons that are inside the diamond and then the diamond "allow out" the photon, and looses it kinetic energy and momentum and passes it to the photon when it emerges from the diamond.

The Optical Tweezers uses bent light rays

Also, experiments have shown that the direction of the momentum component of Light is in the same direction as the direction that the light is travelling. See Compton scattering

https://en.wikipedia.org/wiki/Compton_scattering

(Basically the reflected light was red shifted, and the angle of reflection was correlated with the amount of red shift or momentum loss)

(Einstein's Photoelectric effect)
https://en.wikipedia.org/wiki/Photoelectric_effect

Let's look at some classical momentum physics using billiard balls of different masses.

Two balls collide with perfect elasticity. Or rather one ball is stationary and another ball collide into it. As you vary the mass of the balls, you will observed that perfect transfer of momentum, and energy, occurs when both balls have equal mass. This is actual a form of impedance matching which Tesla was brilliant at (Electrical circuits have sometime similar to mass). Recall Newton's cradle

https://en.wikipedia.org/wiki/Newton%27s_cradle There is perfect momentum transfer and energy transfer. It does not matter the velocities of the balls. If they travel at different speeds and collided then the momentum would behave as if the balls pass through each other. Ball A would give all its momentum to Ball B, and Ball B would give all its momentum to Ball A. They exchange momentum. This would look cool on newtons cradle (Lift both ends at same time but with different heights).

Now let one of the ball be the size and mass of the earth and the other ball be the size and mass of a tennis ball. (Ignoring gravity) If an astronaut tosses the ball at the earth, you would expect the tennis ball to just bounce back at the astronaut without displacing the earth much. The energy transfer (efficiency) is extremely low. The tennis ball still has virtually all of its initial kinetic energy. This is bad impedance matching. Now there are ways to have better matching. Suppose you could have a billion tennis balls. And together they have the mass equal to that of the earth. And it was possible to toss all the balls simultaneously. This is similar to Tesla's resonance. It must be simultaneous. During a collision, there is a time when kinetic goes to potential. Deceleration occurs, then acceleration occurs. These changes must occur simultaneously like they are in phase to have a maximum in the superposition. Then the energy transfer will be ideal. And the tennis balls will move the earth by passing all of its kinetic and momentum. In this case energy is important.

Normal collisions have loss in energy. Basically not simply billiard ball with one potential energy level. Normally the mechanism is complicated. And has many various energy levels. Energy is lost because it has more ways in which the energy can flow. (And its does not stay in the primary potential energy.)

See a attached xls file to play around with. It does the calculations of repeated hitting a 300 unit mass body m1 with another body m2 which has 1 unit of mass. The idea is to increase the velocity of m1 more and more be repeated collisions. And
https://www.omnicalculator.com/physi...on-of-momentum

Now back to a solar sail with mirrors that collect momentum but inefficient at energy.

If the sail has a dark area, energy and momentum is absorbed. It could be a solar panel. (Yes the mass is much greater that a foiled mirror) Photons would be absorbed (Analogous to collision when ball stops). Some goes to electromotive force and some to heating (vibration of atoms). The photons that heat contribute to a net momentum change. Then the electromotive force is pass to a laser booster. Still a work in progress. (As this is a more complicated energy path it may be more analogous to a type of elastic collision) The solar panels could be stowed like a real sail ship and all of that

LightSail 2
https://en.wikipedia.org/wiki/LightSail#LightSail_2

A laser beam from earth can be used to push a light sail that is in outer space.
https://en.wikipedia.org/wiki/Beam-powered_propulsion

Attached xls
https://anonymousfiles.io/waPLBRBY/

2. quite interesting - and should be more interesting if this is improved on to have high power thrust

3. See? We're moving at impulse speed. We need to start increasing that and then we can start thinking about warp technology after.

4. Originally Posted by khat17
See? We're moving at impulse speed. We need to start increasing that and then we can start thinking about warp technology after.
Now you talking.

I even think we can find a solution for the g force of rapid acceleration on the body. All we need is how to go faster.

G force is problematic because not all atoms are accelerated uniformly. The seat that the pilot sits in accelerates. And touches his back. And compresses his skin which then pushes a next layer, and so on. All the layers did not accelerate at the same time.

Einstein said "when you are free falling in a gravity, you would not know that you are falling if you were in a box and the box was falling as well" "You could not tell if you were not floating in outer space" Providing the gravity space time gradient across all the layers in your body is fairly the same, and said gravity in all layers increase together or decrease together. If such a field is created on the Pilot during acceleration of the craft, and he is in a bubble and allowed to free float, he would not know that he accelerating. Thus no g force problem. Let's say that there are heavy C shape masses around the bubble, and during acceleration, all the C shape masses rotate toward the front causing a strong gravitation attraction to the pilot in that direction. Pilot free falls forward. The craft then moves to match at gravity present. Still a work in progress. When the craft slows down, the C shape masses move to the back of the bubble

A Laser is a device that creates and resonates many photons
https://en.wikipedia.org/wiki/Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation.
A photon with the correct wavelength to be absorbed by a transition can also cause an electron to drop from the higher to the lower level, emitting a new photon. The emitted photon exactly matches the original photon in wavelength, phase, and direction. This process is called stimulated emission.
It is the frequency of the photon that defines the momentum that it has (Albert Einstein's Photo Electric effect). However if a surface has many absorption of in phase photons, then it may see a bigger hit by all the electrons that are involved the absorption (moving together). A giant laser built is space, and is solar powered (large area), could be used to provide external propulsion for the craft. (Beam powered propulsion) The laser would need to lock on and track the craft to the edge of solar system but I think our communication technology is kinda limited at some point.

Tesla's concept of superimpose and resonance can be seen with a transformer and LCR circuit. A transformer can change the momentum of "many slow" moving electrons to a "few fast" moving ones (with some energy loss). Just to expound on ways of balancing load. Tesla was also working on a defensive Teleforce weapon which people called a Death Ray
https://en.wikipedia.org/wiki/Death_ray

Nikola Tesla claimed to have invented a "death beam" which he called teleforce in the 1930s and continued the claims up until his death.[9][10][11] Tesla explained that "this invention of mine does not contemplate the use of any so-called 'death rays'. Rays are not applicable because they cannot be produced in requisite quantities and diminish rapidly in intensity with distance. All the energy of New York City (approximately two million horsepower) transformed into rays and projected twenty miles, could not kill a human being, because, according to a well known law of physics, it would disperse to such an extent as to be ineffectual. My apparatus projects particles which may be relatively large or of microscopic dimensions, enabling us to convey to a small area at a great distance trillions of times more energy than is possible with rays of any kind. Many thousands of horsepower can thus be transmitted by a stream thinner than a hair, so that nothing can resist
https://en.wikipedia.org/wiki/Teleforce
Tesla described Teleforce's operation in 1934, specifying its superiority to the death rays believed to exist at the time:

My apparatus projects particles which may be relatively large or of microscopic dimensions, enabling us to convey to a small area at a great distance trillions of times more energy than is possible with rays of any kind. Many thousands of horsepower can thus be transmitted by a stream thinner than a hair, so that nothing can resist."[5] The nozzle would send concentrated beams of particles through the free air, of such tremendous energy that they will bring down a fleet of 10,000 enemy airplanes at a distance of 200 miles from a defending nation's border and will cause armies to drop dead in their tracks.[3][4]

5. I am aware of the level of parasites that exists today.

I hope to elevated good people to a level where parasites can't reach because of their destructive mentality.

This is why I promote the Karma of peace.

It is a cycle where parasites are in a box and there is peace to progressive people, but if the progressive people created the parasites in prior times, there will be Karma-tic backlash for the treatment of parasites. The parasites will come out the box and put progressive people in another type of box and hell bus loose with parasites unleashed. Even worse when parasites have a strong inheritable bloodline. I want break that cycle in my Karma and just deal with good Karma. Help people. No interest digging a pit for any parasite. Just protect good people. Put good people in a box/level where parasites cannot reach, rather than focusing on putting parasites in a box. And if the parasites want sweetie/money, I may do want I can for them, after I see that good people are sorted out.

A giant laser in outer space in the hands of a parasitic leader is a very bad outcome for me.

Any invention, with a positive intent, a parasite will take it and turn it back ways. It is not the invention that prevent people from having better lives, but how the invention is used.

Karma will bring balance. Be good, and I bet good will follow spiritually.

6. Originally Posted by crosswire
Any invention, with a positive intent, a parasite will take it and turn it back ways. It is not the invention that prevents people from having better lives, but how the invention is used.
Peace to LGBTQ

I mean that a parasite only think of 'dem' self. There is no genuine empathy for others. This mentality is completely different, and opposite in direction from a progressive person. It is my strong opinion that long ago, we were an advanced civilization. It is my opinion that maybe progressive people had "Emps", people who had a big operational empathetic core is their brains, who were rulers. General progressive people had operational emphatic core, but less processing power than emps. Maybe parasites were genetically created with their empathetic core disable. At the time, they would not be considered as parasites but tools for some unknown task. There bloodline was strongly inheritable. They worked from a box because they would have cause destruction on the earth if they were unleashed/unchecked. However maybe again, people relied too much on Emps and did not do any spiritual growth on their own, so the Emps were taken. Individuals were then forced to grow spiritually. Eg Emps solely would have made all the caring decisions. Also maybe parasites did not choose to be parasites. They were born without knowing what love was, and were incapable of knowing. However they were good at pretending because they still had big operational logical cores (in most cases). They may not have liked their box. But in any case, Karma could look at the parasites as being "used". One or more great cataclysms hit the earth. And each time we degressed. Generations had to rebuild without established science teachers, and so on. Then Karmatically, the parasites came out their box and "used" back progressive people. Parasites slowly sweep the globe as they migrated. Each time it was tek tek tek. Everything belong to dem. Everything dem see they want and they don't care how they got. And they colonize and colonized. And pass their strong blood line to others. They don't stop until nothing no left that was not colonized. Visa, Country borders, all because of the mentality Parasites. BTW, it it my strong opinion that slave Backra masters were sociopaths aka high level parasites. Parasites stole technology and stuff. Also, they are good con artists to trick and lie to get same tech and stuff. And it is because of this selfish mentality of parasite why a lot of tech is used in wars. When a progressive scientist can think of a tech to help people, here comes the parasite to take it. Then as they only think of themselves, have no interest to use the tech as it was initially intended. They have no regard for others and use the tech in unimaginable heinous way to only benefit themselves.

Whether all of that above is true or not, it is our duty/purpose to love & protect one another. Do not focus on hate but on love and life.

7. Your last 2 posts seem to go on an entirely differently tangent than what this started out to be.

You're concerned parasites are going to misuse solar sails?

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