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[ 17 posts ] |
The light has mass and weight......
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Space Station Commander ![]() ![]()
Joined: Wed Aug 18, 2004 8:47 am
Posts: 521 Location: Science Park, Cambridge, UK ![]() |
Look up light diffusion.
Look up electromagnetic wave (light) propagation. Buy a physics textbook. |
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Space Walker ![]() ![]()
Joined: Sun May 16, 2010 6:36 pm
Posts: 113 ![]() |
If it's attracted by gravity... where does it fall?
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Spaceflight Trainee ![]() ![]()
Joined: Mon Feb 28, 2011 10:27 am
Posts: 32 Location: Earth, Australia ![]() |
Light does not have mass, light is an electromagnetic wave.
Light does have momentum, which is what might be getting you here. E=mc^2 P=mv, where v=c, P=mc m=E/(c^2) sub m into P=mc P=E*c/(c^2)=E/c Momentum of a quanta of light is equal to the energy of the photon divided by its velocity. However, light still does not have mass, I used the equivalency principle that mass and energy are interchangeable, and light is energy. Hence, as an energy, can be entered into the momentum equation. Light can be bent by very large gravitational forces, hence gravitational lensing. But when I say very large, I'm talking stellar-mass-sized. Not Earth-sized (which is pathetically small). Quote: Why light produces waves, because it weighs. Let us remember that the waves produces a touch. You are confusing matter waves and energy waves. Pick up a physics text book and actually read it. Seriously. Light form some sources does not appear to reach the clouds because the light emmitted from the sources spreads out over the distance. The intensity of light form a source decreases over distance by the inverse square law. Do you actually read what anyone says? Quote: Buy a physics textbook Do it. Do it now. _________________ "Don't tell me that man doesn't belong out there. Man belongs wherever he wants to go--and he'll do plenty well when he gets there." Wernher von Braun, Time magazine, 1958 |
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Spaceflight Trainee ![]() ![]()
Joined: Mon Feb 28, 2011 10:27 am
Posts: 32 Location: Earth, Australia ![]() |
Photon has energy, it is energy. It is an electromagnetic wave composed of fluctuating electric fields orthogonal to fluctuating magnetic fields which perpetuate each other.
It does not say *anywhere* in that article that photons do not have energy. It says that the energy of the photon is related to it's frequency. If you actually read the page all the information is right there. Also: try to keep your scientific faux pas in one thread. You are confusing mechanical waves, matter waves and energy waves. Here is a fun website that will help you. http://library.thinkquest.org/10796/ch8/ch8.htm http://en.wikipedia.org/wiki/Mechanical_wave My advice is abandon whatever you currently think you know and start from scratch. Sounds hard, but you've clearly messed up something fundamental when you were attempting to learn, and now you can't grasp this physics. _________________ "Don't tell me that man doesn't belong out there. Man belongs wherever he wants to go--and he'll do plenty well when he gets there." Wernher von Braun, Time magazine, 1958 |
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Spaceflight Trainee ![]() ![]()
Joined: Mon Feb 28, 2011 10:27 am
Posts: 32 Location: Earth, Australia ![]() |
victorespinoza wrote: If "It is an electromagnetic wave composed of fluctuating electric fields orthogonal to fluctuating magnetic fields that perpetuate between Yes.", then it has weight. Let us remember that the waves are produced by a touch. There is no logical way that you can get from what I said to your conclusion. Electromagnetic waves have no mass, they have no weight. They are energy, not mass. _________________ "Don't tell me that man doesn't belong out there. Man belongs wherever he wants to go--and he'll do plenty well when he gets there." Wernher von Braun, Time magazine, 1958 |
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Spaceflight Trainee ![]() ![]()
Joined: Mon Feb 28, 2011 10:27 am
Posts: 32 Location: Earth, Australia ![]() |
...
You're a git, bro. _________________ "Don't tell me that man doesn't belong out there. Man belongs wherever he wants to go--and he'll do plenty well when he gets there." Wernher von Braun, Time magazine, 1958 |
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Space Station Member ![]() ![]()
Joined: Mon Feb 25, 2008 9:51 am
Posts: 455 Location: Vienna, Austria, Europe, Earth ![]() |
Maybe you should start discussing your ideas with people that speak your language first. Even if we disregard most of the logical problems, some of your statements still do not make any sense whatsoever...
And no, English isn't my first language either. _________________ pride comes before a fall |
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Space Station Member ![]() ![]()
Joined: Mon Dec 12, 2011 6:40 am
Posts: 476 Location: California and Michigan ![]() |
Are therw conditions where energy can be made into sub atomic particles?
_________________ Let not the bindings of society hold you back from improving it.... the masses follow where the bold explore. |
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Space Station Commander ![]() ![]()
Joined: Sun Jan 17, 2010 2:21 pm
Posts: 547 Location: B.O.A. UK ![]() |
Sigma wrote: Are therw conditions where energy can be made into sub atomic particles? Yes that is what a lot of those experiments at CERN are all about creating and studying subatomic particles created from the energy given off by collisions of bits of matter and antimatter accelerated to near light speed. _________________ Someone has to tilt at windmills. So that we know what to do when the real giants come!!!! |
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Space Station Member ![]() ![]()
Joined: Mon Dec 12, 2011 6:40 am
Posts: 476 Location: California and Michigan ![]() |
Could one maintain x atoms in loop and emit mass with no loss of origjnal atoms? Generation of mass to accelerate would make an energy dependent infinite thruster.
_________________ Let not the bindings of society hold you back from improving it.... the masses follow where the bold explore. |
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Moon Mission Member ![]() ![]()
Joined: Mon Dec 18, 2006 11:15 pm
Posts: 1050 Location: Columbus, GA USA ![]() |
No because the collisions that creates the particles destroys the original matter. They get "broken" into their constituent parts as part of the process of decay to energy.
It takes much MUCH more energy to break particles to their elementary sub-particles than could ever be retrieved. There is no free lunch to be had here. This thread makes even less sense without Adrino's posts in it. I miss him. ![]() |
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Space Station Member ![]() ![]()
Joined: Mon Dec 12, 2011 6:40 am
Posts: 476 Location: California and Michigan ![]() |
What about a means to amplify vacume fluctuations? Can one make a beam of gluons collide with a beam of bosons and mass be emited?
I wonder if through known means energy could be made into mass to use as relitivistic speed propellent? I will try and think of some tests. _________________ Let not the bindings of society hold you back from improving it.... the masses follow where the bold explore. |
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Space Station Member ![]() ![]()
Joined: Thu Mar 06, 2008 9:22 pm
Posts: 266 ![]() |
You could build a 'vehicle' that took in solar power and used it to create matter, then accelerated the matter as a thruster.
But it would be incredibly heavy and inefficient, and would create no perceptible thrust in comparison to the sail effect of the ginormous solar panels necessary. |
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Spaceflight Enthusiast ![]() ![]()
Joined: Sat Jan 07, 2012 1:59 am
Posts: 2 Location: The High Desert ![]() |
You don't need mass to propel something, you need momentum (mass times velocity). The law of momentum conservation says that if matter is thrown out the back of a rocket with some momentum, the rocket gains an equal amount of momentum in the opposite direction.
Light does have momentum,* so all you need to do is shine a laser beam in one direction, and you'll accelerate in the other direction. Of course, this doesn't work so well in practice. This is because you need a lot of energy to produce enough light to propel anything. The equation that relates energy and momentum for light is: E=pc where p is momentum and c is the speed of light. If you plug in numbers, you'll find that you need a lot of energy to produce a beam of light with any useful amount of momentum. That's why you don't fall over when you fire up your laser pointer. I'm certain that people have thought of doing propulsion using high intensity lasers, but I would suspect that it would be highly impractical with today's technology. -- *You might ask how light can have momentum, given that momentum is defined as mass times velocity. In the case of massless matter like light, we make an exception and define momentum (for a photon) as p=h/l, where h is Planck's constant, and l is the length (if you're skeptical, check the units). |
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Space Station Commander ![]() ![]()
Joined: Mon May 31, 2004 9:47 pm
Posts: 827 Location: Yerushalayim (Jerusalem) - capital of Israel! ![]() |
Solar sails work by being pushed by light. http://en.wikipedia.org/wiki/Solar_sail
_________________ “Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.” -Anonymous |
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