The speed of light

[Crazyhole]

Just kind of a fun intellectual exercise here. Einstein kind of proved his theory of relativity wrong when he figured out that light is affected by gravity. Now that we can actually observe this, how is it possible to calculate the speed of light? Does the speed of light accelerate when getting closer to a source of gravity? Does a larger source of light slow down its speed from the get-go due to a larger force of gravity pulling it back? Can it accelerate after breaking away from that gravitational pull and begin to be influenced by other sources of gravity?

 

[Boosted87]

One of my favorite thought experiments to understand the very basics of this stuff is a photon clock.
Basically two plates with a single photon bouncing up and down between them. If the observer is stationary relative to the clock, then the photon has travels the distance between the plates. But if the photon clock is moving relative to the observer, then the path of the photon is not purely vertical since it's moving horizontally to the observer. So just imagine something like a 45 degree triangular wave pattern as the motion observed by the stationary person.

So an observer moving with the clock sees the distance traveled as x, the stationary observer sees the distance traveled as 1.4x - basically the hypotenuse of the triangle wave. Remember that the unique property of light is that it's speed is measured the same in all reference frames. Well if the velocity of the photon is measured the same by both observers, but the distance traveled is different, then the amount of time elapsed has to be different also.

Thus time dilation. I know this didn't answer your question but it's the simplest way to understand the basics of this stuff that I know of.

 

[Boosted87]

Just kind of a fun intellectual exercise here. Einstein kind of proved his theory of relativity wrong when he figured out that light is affected by gravity. Now that we can actually observe this, how is it possible to calculate the speed of light? Does the speed of light accelerate when getting closer to a source of gravity? Does a larger source of light slow down its speed from the get-go due to a larger force of gravity pulling it back? Can it accelerate after breaking away from that gravitational pull and begin to be influenced by other sources of gravity?

I think you're initial premise here is wrong? Proving that light was effected by gravity as predicted by Einstein proved General Relativity correct and proved Newtonian gravity flawed.

This Is How, 100 Years Ago, A Solar Eclipse Proved Einstein Right And Newton Wrong

The solar eclipse of May 29, 1919, was the nail in the coffin of a Newtonian Universe.

www.forbes.com

 

[Crazyhole]

I think you're initial premise here is wrong? Proving that light was effected by gravity as predicted by Einstein proved General Relativity correct and proved Newtonian gravity flawed.

This Is How, 100 Years Ago, A Solar Eclipse Proved Einstein Right And Newton Wrong

The solar eclipse of May 29, 1919, was the nail in the coffin of a Newtonian Universe.

www.forbes.com

How can that be? If light is affected by gravity, I would have to believe that it can be slowed down or even reversed. Like with a black hole where spaghettification supposed occurs, it would mean light is increasing in velocity the closer it comes to the event horizon. Or, for that matter, scientists believe that there are galaxies moving away from ours, accelerating to point of breaking the speed of light, at which point they disappear. What is causing those galaxies to accelerate?

 

[Boosted87]

How can that be? If light is affected by gravity, I would have to believe that it can be slowed down or even reversed. Like with a black hole where spaghettification supposed occurs, it would mean light is increasing in velocity the closer it comes to the event horizon. Or, for that matter, scientists believe that there are galaxies moving away from ours, accelerating to point of breaking the speed of light, at which point they disappear. What is causing those galaxies to accelerate?

I love this topic so I'll split up my reply into 2 or 3 posts cause it's nuts. And yea none of this makes any sense on it's face. Which is why the dudes that figure it out are geniuses.

First key thing to understand - the speed of light is the same in all reference frames. So imagine Nolan Ryan is pitching fastballs at 100mph on train moving at 50mph. If you're on the train with him, you're measuring the 100mph velocity.

But if you're off the train and you're staring at it from the side, the velocity you measure of the baseball will be the pitch speed + the speed of the train. Depending on direction of the throw, you'll clock it at either 150mph or 50mph.

Light doesn't work that way. If Nolan Ryan is on a space ship traveling at near the speed of light turning on a laser instead of throwing fastballs, logic would suggest you would measure the speed of the laser light at C + Speed of Ship. But you won't. It will still measure at C from your reference frame. No matter what.

This is what makes light unique. It doesn't ever speed up or slow down, but the length of the path it travels changes, which makes time appear to speed/up slow down depending on reference frame (time dilation).

 

[Crazyhole]

I love this topic so I'll split up my reply into 2 or 3 posts cause it's nuts. And yea none of this makes any sense on it's face. Which is why the dudes that figure it out are geniuses.

First key thing to understand - the speed of light is the same in all reference frames. So imagine Nolan Ryan is pitching fastballs at 100mph on train moving at 50mph. If you're on the train with him, you're measuring the 100mph velocity.

But if you're off the train and you're staring at it from the side, the velocity you measure of the baseball will be the pitch speed + the speed of the train. Depending on direction of the throw, you'll clock it at either 150mph or 50mph.

Light doesn't work that way. If Nolan Ryan is on a space ship traveling at near the speed of light turning on a laser instead of throwing fastballs, logic would suggest you would measure the speed of the laser light at C + Speed of Ship. But you won't. It will still measure at C from your reference frame. No matter what.

This is what makes light unique. It doesn't ever speed up or slow down, but the length of the path it travels changes, which makes time appear to speed/up slow down depending on reference frame (time dilation).

What if you're on a ship traveling at the speed of light and you shine a flashlight in the opposite direction? Does that light stand still, or do they move away from one another at twice the speed of light?

 

[Boosted87]

How can that be? If light is affected by gravity, I would have to believe that it can be slowed down or even reversed. Like with a black hole where spaghettification supposed occurs, it would mean light is increasing in velocity the closer it comes to the event horizon. Or, for that matter, scientists believe that there are galaxies moving away from ours, accelerating to point of breaking the speed of light, at which point they disappear. What is causing those galaxies to accelerate?

Einstein's big break through with relativity is that what we observe as gravity is actually curvature in space-time. If you can get your brain to re-map to this perspective, everything makes more sense. Imagine you're in a space ship and you're going to fly by earth close enough to be significantly impacted by our gravity. As you fly by earth, our gravity will change your trajectory.

Now, you can think about this like Newton did - two masses exert a force on each other - pulling your spaceship towards earth. Or think like Einstein, and imagine that earth's mass was physically bending the space around it. Your space ship is simply traversing the bent space - like going over a hill on a landscape. So if you imagine space as a 3D wireframe where the grid gets deformed by massive object, you can imagine the paths that objects (including photons) would take through this curved space.

Thus a massless object (photon) is still effected by gravity - because the physical space is deformed. Hence Einstein's eclipse experiment.

 

[Crazyhole]

This is the first photo of a black hole

In April 2017, scientists used a global network of telescopes to see and capture the first-ever picture of a black hole, according to an announcement by researchers at the National Science Foundation Wednesday morning. This is the first direct visual evidence that black holes exist.

www.cnn.com

I've had a problem with this picture since it came out last year. Why would we see a corona around a black hole? Shouldn't light be sucked into it from every direction, thus leading to either no light being seen at all, or just a total ball of light? How can we be in a point of view to see it as a cross section?

 

[Crazyhole]

Einstein's big break through with relativity is that what we observe as gravity is actually curvature in space-time. If you can get your brain to re-map to this perspective, everything makes more sense. Imagine you're in a space ship and you're going to fly by earth close enough to be significantly impacted by our gravity. As you fly by earth, our gravity will change your trajectory.

Now, you can think about this like Newton did - two masses exert a force on each other - pulling your spaceship towards earth. Or think like Einstein, and imagine that earth's mass was physically bending the space around it. Your space ship is simply traversing the bent space - like going over a hill on a landscape. So if you imagine space as a 3D wireframe where the grid gets deformed by massive object, you can imagine the paths that objects (including photons) would take through this curved space.

Thus a massless object (photon) is still effected by gravity - because the physical space is deformed. Hence Einstein's eclipse experiment.

This is cool. So basically what you are saying is that light is actually taking a straight path, but its the universe that is actually curved?

 

[THX_UCF2]

This is cool. So basically what you are saying is that light is actually taking a straight path, but its the universe that is actually curved?

I think that is some of the theories around how everything is moving away from us knowing we're not the center.

 

[Crazyhole]

I think that is some of the theories around how everything is moving away from us knowing we're not the center.

Can there even be a center? If so, and everything is moving away from it that would mean there is a humongous void in space that is growing exponentially. It would also mean, if things are linear, we aren't moving away from everything because we would necessarily be taking the same trajectory as something else, be it in front of us or behind us.

 

[Crazyhole]

What would cause a nebula, being round, evolve into a galaxy that is flat?

 

[Boosted87]

What if you're on a ship traveling at the speed of light and you shine a flashlight in the opposite direction? Does that light stand still, or do they move away from one another at twice the speed of light?

The ship is no different than any other moving object. All motion is relative you can pick any point at fixed and measure from there. Earth is moving through space just like a space ship would be. Somewhere there's a star that we observe to be moving away from us at near the speed of light. If we were on that star, we would observe earth moving away at near the speed of light. In one reference frame, earth is not moving, in the other, earth is moving at near the speed of light. Neither reference frame is right or wrong.

From a far away observer, just imagine watching through a telescope, like filming a movie. If the light could move at 2C, then you'd observe the light source being on before observing the on-switch was flipped. Instead, the photons leaving the light source and the ones bouncing off the switch are traveling at the same speed so you see that happen in sync.

 

[Boosted87]

This is cool. So basically what you are saying is that light is actually taking a straight path, but its the universe that is actually curved?

Yup. The photons are just riding on the curved space. When you hear talk about the "curvature of space-time" that's basically what is meant. This is a pic representing Einstein's eclipse experiment. Einstein correctly predicted where we would observe the stars IF space was being bent. He was right.

 

[Crazyhole]

Lol, how about this one: you can't see anything in 3 dimensions. You know that something has height, width, and depth, but you can only see height and width. Only when you move around an object can you observe depth, but even then you are still seeing it in 2 dimensions.

 

[Boosted87]

This is the first photo of a black hole

In April 2017, scientists used a global network of telescopes to see and capture the first-ever picture of a black hole, according to an announcement by researchers at the National Science Foundation Wednesday morning. This is the first direct visual evidence that black holes exist.

www.cnn.com

I've had a problem with this picture since it came out last year. Why would we see a corona around a black hole? Shouldn't light be sucked into it from every direction, thus leading to either no light being seen at all, or just a total ball of light? How can we be in a point of view to see it as a cross section?

Think of like an asteroid that almost hits earth but doesn't. It didn't quite get close enough for our gravity sync to pull it in, but we did change it's trajectory. Or think about those marble tables at the science center where it slowly spins around the outside then faster and faster until it approaches the middle.

What you see emitting from the black hole is all the crap in a death spiral but not past the event horizon. While the marbles are still spinning around the table light is escaping. When they reach the point light can't escape (event horizon) it goes black.

 

[Crazyhole]

Yup. The photons are just riding on the curved space. When you hear talk about the "curvature of space-time" that's basically what is meant. This is a pic representing Einstein's eclipse experiment. Einstein correctly predicted where we would observe the stars IF space was being bent. He was right.

So on that picture, say you are standing on the left side of the object on the left. You can't see the light passing that object because it's traveling past you at the speed of light unless it bounces off of an object in the distance. The light is there, you just can't see it.

 

[Crazyhole]

Think of like an asteroid that almost hits earth but doesn't. It didn't quite get close enough for our gravity sync to pull it in, but we did change it's trajectory. Or think about those marble tables at the science center where it slowly spins around the outside then faster and faster until it approaches the middle.

What you see emitting from the black hole is all the crap in a death spiral but not past the event horizon. While the marbles are still spinning around the table light is escaping. When they reach the point light can't escape (event horizon) it goes black.

But why would we see it in 2 dimensions? Light should be traveling into it from 360 degrees, unless the light in front of it is accelerating beyond the speed of light.

 

[Boosted87]

Lol, how about this one: you can't see anything in 3 dimensions. You know that something has height, width, and depth, but you can only see height and width. Only when you move around an object can you observe depth, but even then you are still seeing it in 2 dimensions.

I always got a kick out of the Flatland thing and I think it's a great analogy for how completely unexplainable things might simply be our inability to fully observe them in all dimensions.

Basically, you can only see and experience an infinitely thin cross section of a 3D world. So you see a line 360 degrees around you. If a simple object like an orange passed through your plane of existence, it would start as a point that grew to the diameter of the orange then shrink away to nothing.

This unexplainable miracle might lead to a new religion, confirm someone's belief in aliens, or whatever. Yet from the perspective of a 3D dimensional universe, someone just dropped an orange. With modern theories of physics thinking there may be many more than 3 spatial dimensions - combined with "time" being considered the 4th dimension.

If time is not the linear construct we experience, then ghost stories might just be like the orange passing through flatland - completely unremarkable in the grand scheme of things, but unexplainable from our limited viewpoint.

 

[Crazyhole]

I always got a kick out of the Flatland thing and I think it's a great analogy for how completely unexplainable things might simply be our inability to fully observe them in all dimensions.

Basically, you can only see and experience an infinitely thin cross section of a 3D world. So you see a line 360 degrees around you. If a simple object like an orange passed through your plane of existence, it would start as a point that grew to the diameter of the orange then shrink away to nothing.

This unexplainable miracle might lead to a new religion, confirm someone's belief in aliens, or whatever. Yet from the perspective of a 3D dimensional universe, someone just dropped an orange. With modern theories of physics thinking there may be many more than 3 spatial dimensions - combined with "time" being considered the 4th dimension.

If time is not the linear construct we experience, then ghost stories might just be like the orange passing through flatland - completely unremarkable in the grand scheme of things, but unexplainable from our limited viewpoint.

Lol, that's actually what made me start thinking about this again. What we know as time is really just a measure of motion that we can observe. Time may not be static. A simple analogy, which i think came from Einstein, is this: imagine a clock. You see the clock because light is reflecting off of it at the speed of light. If you moved away from the clock at the speed of light, time would appear to stand still. If you could travel towards the clock at the speed of light, you would be moving forward in time. If you traveled away from it at faster than the speed of light, you'd be going backwards in time.

 

[Boosted87]

Lol, that's actually what made me start thinking about this again. What we know as time is really just a measure of motion that we can observe. Time may not be static. A simple analogy, which i think came from Einstein, is this: imagine a clock. You see the clock because light is reflecting off of it at the speed of light. If you moved away from the clock at the speed of light, time would appear to stand still. If you could travel towards the clock at the speed of light, you would be moving forward in time. If you traveled away from it at faster than the speed of light, you'd be going backwards in time.

OK so logically we should jump to "spooky action at a distance." Someone smarter than me explaining:

One of the strangest aspects of quantum physics is entanglement: If you observe a particle in one place, another particle—even one light-years away—will instantly change its properties, as if the two are connected by a mysterious communication channel. Scientists have observed this phenomenon in tiny objects such as atoms and electrons. But in two new studies, researchers report seeing entanglement in devices nearly visible to the naked eye.

Einstein’s ‘spooky action at a distance’ spotted in objects almost big enough to see

Entangled electronic devices could help scientists make a quantum internet

www.sciencemag.org

This just shows us how much more we have to understand about the universe.

 

[Boosted87]

So on that picture, say you are standing on the left side of the object on the left. You can't see the light passing that object because it's traveling past you at the speed of light unless it bounces off of an object in the distance. The light is there, you just can't see it.

Yea I mean I'm way too dumb to understand all this. But the whole "light is both a wave and a particle" thing is fascinating. But everything you see is is the result of a photon reflecting off something and hitting the receptors in your eye. But to your point no different than trying to see around a corner. The photons are there but they're not hitting your eye.

I think it's crazy that some star millions of light years away is ejecting enough photos so that any eyeball in a 100 million light year sphere would be able to detect it is nuts.

 

[Crazyhole]

Yea I mean I'm way too dumb to understand all this. But the whole "light is both a wave and a particle" thing is fascinating. But everything you see is is the result of a photon reflecting off something and hitting the receptors in your eye. But to your point no different than trying to see around a corner. The photons are there but they're not hitting your eye.

I think it's crazy that some star millions of light years away is ejecting enough photos so that any eyeball in a 100 million light year sphere would be able to detect it is nuts.

I've thought about that as well. The vacuum of space isn't really a vacuum, there are particles everywhere that should be reflecting light back to the source. How any amount of light could pass through such large distances and actually get here without having been blocked or refracted seems almost impossible. It makes me wonder if our ability to measure the size of the universe is entirely flawed.

 

[Crazyhole]

OK so logically we should jump to "spooky action at a distance." Someone smarter than me explaining:

One of the strangest aspects of quantum physics is entanglement: If you observe a particle in one place, another particle—even one light-years away—will instantly change its properties, as if the two are connected by a mysterious communication channel. Scientists have observed this phenomenon in tiny objects such as atoms and electrons. But in two new studies, researchers report seeing entanglement in devices nearly visible to the naked eye.

Einstein’s ‘spooky action at a distance’ spotted in objects almost big enough to see

Entangled electronic devices could help scientists make a quantum internet

www.sciencemag.org

This just shows us how much more we have to understand about the universe.

Oh man, now you're getting into matrix mechanics, which makes my head spin. The whole schrodingers cat thing blows my mind. I mean it kind of makes sense, how you can't observe something without affecting it but that is so far from my ability to quantify its just a mind trip.

Yeah, that galaxy thats a trillion miles away exists there, but since I can observe it, its also exists here. So weird.

 

[Crazyhole]

What makes the earth rotate? Why does it rotate on a single axis?

 

[Crazyhole]

Are photons absorbed by the object they hit, or do they reflect off of it at the speed of light? If it was the latter, in theory you should be able to capture light in a container and keep it illuminated forever.

 

[Crazyhole]

If light contains no mass, its theoretically possible that you could collect all light in the universe at a singular point, meaning space and distance are independent of it. If that's the case, then two other things could operate in the same way, sound waves and our own thoughts. Sound waves are kind of boring in this, but thoughts are a totally different story. Thoughts aren't energy and contain no mass, so they shouldn't be restricted by distance or time. I'm kind of getting into quantum entanglement here, but its pretty fascinating to try to wrap your mind around

 

[Crazyhole]

If a black hole was right in front of you, you wouldn't know it was there.

 

[Crazyhole]

Sorry, I'm taking notes for myself here.

If the ultimate measure of time is the speed of light, time can be eliminated by a purely dark object. If I can't see it I have no idea how far away or close it is to me because there js no way to measure the distance. Does that make it anti-matter? How does physical perception and concept limit it? If i stretch my arm out in pure dark how do i know how far it actually reaches? Is it limited to what I experience when I can see it or is it an infinite distance? Does this have something to do with finding a dark quiet room to meditate in order to hear God?

 

[Crazyhole]

A person can expel energy. We see this every time we exhale in cold air. Are we limited to that ability of moving energy from one place to another? Can it be consolidated and controlled? Why do I need my hands to move a cup if my body has the ability to move particles in the air that equal its mass?

 

[Crazyhole]

Pure light and pure darkness are impossible to experience. Both always exist.

 

[Crazyhole]

God is light.

 

[Crazyhole]

When Noah opened his eyes, light filled the room

 

[Crazyhole]

Schrodinger was right but he ****ed up with the example. Opposites exist at the same time, and have to. It wasn't a dead cat or an alive cat, it was a cat or the opposite of a cat. 0=2. 0=1-(+1). 2 positive quantities equal 0.

 

[KnighttimeJoe]

SMH. 7 posts after 10:30pm on a Saturday night. During New Year's weekend. This is nothing short of pathetic.

In the New Year, I sincerely hope you get a life, find a girlfriend/boyfriend, and work on your social skills, which are clearly lacking. Stop drinking yourself to into a lonely stupor on Saturday nights on a freaking message board and seek human companionship.

 

[DaShuckster]

"It’s so hard to believe in anything anymore. I mean, it’s like, religion, you really can’t take it seriously, because it seems so mythological, it seems so arbitrary…but, on the other hand, science is just pure empiricism, and by virtue of its method, it excludes metaphysics.

I guess I wouldn’t believe in anything anymore if it weren’t for my lucky astrology mood watch."

Steve Martin

 

[Knight_Classes_begin_7pm]

Just kind of a fun intellectual exercise here. Einstein kind of proved his theory of relativity wrong when he figured out that light is affected by gravity. Now that we can actually observe this, how is it possible to calculate the speed of light? Does the speed of light accelerate when getting closer to a source of gravity? Does a larger source of light slow down its speed from the get-go due to a larger force of gravity pulling it back? Can it accelerate after breaking away from that gravitational pull and begin to be influenced by other sources of gravity?

GENERAL relativity.

 

[Crazyhole]

Light doesn't exist.

 

[Crazyhole]

For any equation to be correct, you have to be able to reverse the equation. That means that if energy=mass x the speed of light squared is true, it also means that mass= the speed of light squared divided by energy. Basically this means mass cannot be a constant, so how can it be a determinant factor in energy?

 

[Boosted87]

For any equation to be correct, you have to be able to reverse the equation. That means that if energy=mass x the speed of light squared is true, it also means that mass= the speed of light squared divided by energy. Basically this means mass cannot be a constant, so how can it be a determinant factor in energy?

This crap is weird. Basically, mass and energy are the same thing. The speed of light is the constant that connects them. So if you want to know how much energy is bound up in a mass, you can calculate that with c. If you converted a given mass into pure energy (electromagnetic radiation) this tells you how much energy you'd have.

Honestly, this crap is mostly above my head. I read a book and think I get it but then a few years later I'm lost again.