Didymus

I think people here are getting a bit carried away with the correlation between time and space. Yes, matter is moving outward through space... But to state that time is expanding as space expands... Seems to suggest that the direction of space affects the direction of time. I.e. if, by any means, the universe were to begin retracting back in on itself, time would stop moving forward. Of course, I doubt that's your intention... But it's an implication of that statement. Note, or we're to accept the idea that time is a perpendicular dimension of spacetime, as one point in space experiences a sequence of moments in time, likewise, the result would be each moment would be defined by a universal coordinant in time.

Since the moderation staff keeps bringing the topic up: The overarching question is "Why does light (behave a certain way)." The answer of "it doesn't always" is a completely on topic response. The topic of the forum is not different mediums... yet, count how many people specified that light only moves at C in a vacuum. Although black hole's ability to alter light's course was brought up, the event horizon wasn't specifically mentioned. It's equally applicable to mention that the mainstream perspective is that light can be trapped at the event horizon of a black hole, neither escaping, nor being drawn in. So, the OP's "Why does light move at C" can be given the response of "it doesn't... if it's trapped in an event horizon." To the same extent, no... universal expansion itself isn't the topic of this thread. But "Why does light move at C?" ... in the case of universal expansion, according to mainstream understanding, it doesn't (relative to objects far enough away that the light can never reach it). Point was made a couple days ago... you could respond to it or ignore it. If you'd like the thread to go in a different direction... common sense says to start talking about the direction you'd like the thread to go. But if the moderation staff feels the need to address me, I will respond in the method they chose to address me. Send me a message in private if you'd like a private response. But if -you- address me in-thread, my response to your address can not be considered off-topic. You're the one driving the 'off-topic' topic. Were it up to me, this whole tangent you guys keep sticking to would be dropped, and we can get back to physics instead of politics.

My post was entirely on topic and very polite. Perhaps you could have a private discussion with me if you'd like clarification instead of publically calling my questions on the topic at hand "speculative trash." Rule 2.8. This is a -discussion- forum. Not a place for one viewpoint to be preached from A soap box and valid questions to be rejected. Of course, I'd prefer to have this conversation of what we think of each other personally in private.

Swon. We are discussing mainstream theories, including important questions tosk shen considering those theories. The forum rules specifically disallow the suppression of open discussion and different considerations of mainstream theories. considering the speed of light in "all inertial frames" includes inertial frames within an expanding universe. If you have an explanation consistant with the popular theory as to how celestial bodies (with valid inertial frames) can be moving at a speed greater than C relative to other bodies due to an observably expanding universe to the point where light from one body can't make it to the other because of their relative motion.... I would love to see it. I'm sure I'm far from the first person to think of such an example, therefore, many people may benefit from having the question answered. If you haven't considered it... Perhaps you should. By considering examples of situations where a theory -appears- to be weak, we test it. Either we will find an explanation and gain a better understanding of a correct theory, or we can find a weakness in a theory and learn from it. Note I am not offering an alternative theory or personal viewpoint. Only contributing to the conversation at hand to ask how you believe the popular theory applies to a valid circumstance.

I don't mean to insinuate that "you have misunderstood" anything. Only that that topic of this thread is "Why does light travel at 299,792,458 meters per second" and in the situation you brought up, light traveling from object A to B is not traveling at 299,792,458 meters per second relative to B when A is moving away at a speed faster than 299,792,458 meters per second. If you explain it as neither object moving at all, but space growing (or shrinking) between two objects, it's an interesting perspective. But whatever frame of reference you define as moving... if light can never reach a certain object, then that light in your example can not be approaching that object at the constant of C as suggested in the original post. The question this begs would be at what point this breaks down.

While I would love to go into the psychology of your response, I'll simply point out that strange made a valid point, for which I asked clarifications on -his- viewpoint. So, the topic of this thread is why the speed of light is exactly what it is. This inherently calls into question whether its immutable common to all frames of reference (SR) or only it's source. If it does not offend out empress, strange has pointed out that distant celestial bodies move away from us at speeds exceeding the speed of light and therefore their light can never reach us. In the spirit of this thread's topic, if object A and B are "X" lightyears apart when the light is emitted, and the speed of light is constant, how can light take more than "X" years to travel from A to B? (note, there are no scary "unpopular opinions" posted above. I'm challenging strange's suggestion, which goes against popular opinion.)

Thank you for your polite response, strange. So, if: "There are galaxies receding so fast that light from them will never reach us." (I agree with this) Yet the speed of light relative to all frames of reference is immutable, according to SR, that light must get to us at some point. If object A and B are X lightyears away, if light is emitted from either object toward the other, light should reach the opposite object in exactly X years, regardless of the direction or rate either object is traveling during those X years. Agree or disagree?

My point exactly. One can observe a minimum of 10 pounds of force being constantly applied if a 10 pound magnet sticks to the underside of a table. Obviously to do any work either the magnet has to move across wires or wires have to move across a magnetic field. Just like uranium doesn't just generate electricity sitting on a table. You have to harness it by putting it close enough to water to boil, pushing turbines, rotating wires around a magnetic field and pushing those electrons. Likewise, with magnets. Create a magnetic pressure differential so that an array of magnets on a shaft constantly goes toward poles it can never reach to yield rotation. Then convert axial kinetic energy to electricity and win.

Define local. Most people I've seen touch on this topic always brush it off with a tangent as shown below. Conveniently denying an aether when it goes against relativity, then mandating the existence of an aether when they need it to exist. Exactly what I meant when I pointed out how unscientific relativity is. It becomes unfalsifiable when you see objects moving away from eachother at speeds greater than C, and we just turn around and say "it isn't really the objects moving that fast, but time and space expanding between those objects." Which inherently goes back to necessitating an aether... Even though SR is based upon the lack of evidence of such an aether. So, assume these two objects are traveling away from eachother at a speed greater than C. These two objects emit light toward eachother... Alan, do you believe light from the two objects can reach the opposite objects?

It's a matter of definition. A helicopter sitting on the ground without moving experiences the constant force of gravity and isn't moving because it's already at rest on the ground. That same helicopter hovering in one spot above the ground has a velocity of zero. The rotors and engine is doing quite a lot, but there is no net motion (relative to the ground), yet there is quite a bit of energy needed to overcome the constant force of gravity. Likewise, magnetic and radioactive materials have quite a bit of energy stored within them. Not perpetual, but quite a lot. A bit of uranium sitting on a shelf still has harvestable energy, even if the uranium is stationary. No one suggested that gravitational or magnetic energy is "used up" when it's utilized.

Indeedy. Thermodynamics will probably be pretty hard to turn into a game. What specific principle are you trying to demonstrate in the game? Conservation of energy could be shown by some kind of race involving energy being stored in different states? The light maze idea is great though. Laser pointers can be pretty cheap, then you just need a peg board and some mirrors to put on the pegs. Get some boards on pegs to make a customizable obstical coarse and you're good to go without spending too much money or time.

Indeedy. No machine can be perpetual... Even without thermodynamics, the machine will rust and degrade eventually. Perpetual motion is all around us... For an example, see any object moving through space. Without a resistance, it will travel forever, without slowing. On to the more theoretical stuff: while perpetual machines are impossible, there are great sources of energy not currently in use that have fabulous potential. Stick a 10 pound magnet on the bottom of a table and you can observe it actively applying at least 10 pounds of pressure for as long as it remains magnetized. The challenge is finding a way to generate electricity using the energy already stored in that magnet. For truly perpetual energy: see gravity.

It only becomes impossible if you define it as such. Note that with an expanding universe, objects are moving apart faster and faster. This inherently means that when the universe reaches a certain size, objects on the edge will be traveling beyond the speed of light relative to other objects. Of course, certain people will redefine time to give the illusion of this not being the case via time dilation. No matter what evidence a person presents, reality is simply redefined by altering the definition of time and space in order to protect the omnipotence of C.

Change the subject all you want. Fact is, the speed of light being constant relative to anything other than its source has never been measured. To skew so much of science to protect a theory that has never been adequitely supported... Yet is so obviously falsified (by the Doppler effect) is not science. That's religon. Don't try to shift blame as though we are the ones "abandoning science" by requesting direct evidence before we put faith in a thing that defies logic. Swans, math is a language that quantifies what we observe. If you observe a thing, completely misrepresent it, but quantify that misrepresentation with accurate numbers.... We're left with nothing more than a very well articulated bit of foolishness. Numbers are right, but you're looking at it entirely upside down.

Alan... Might wanna bring it down a notch or two. Plenty of people outside of "primary school children" may have areas of interest outside of the physics of light. Besides, while I agree with your intent, that photons don't really "accelerate" in that they're massless and can not experience G-forces and that they're traveling at the speed of light upon emission... They can still be considered to accelerate in some senses of the word. Think of a coordinate system sth light teaveling directly along the Y axis. That light goes through a gravitational field and the direction changes to a few degrees into the x axis. While the photon is moving at the same speed, it's progress along the Y axis has slowed and it's progress along the X axis has increased. It has experienced both acceleration and deceleration... Relatively. A person holding a viewpoint different than your own should not immediately be assumed to be ignorant. As for Swanson: yes. Measurement is important. The calculations for a certain theory (such as relativity) MAY be spot-on... While the variables are still attributed improperly. For example, muons extended lifespan being predictable by relativity. I completely agree that they can be observed places they shouldn't be and the math for relativity explains the relationbetween their speed and their extended life. However, the fact that we observe them CAN mean that muons invariably only live a certain amount of time, and that their motion changes how they experience time, so what looks like more time has past to us seems like the same period of time to them... I.e. they tell time more accurately than time exists.... It's invariably fixed to a completely alterable state. OR, we can take the simple explanation that the high speeds physically change the rate of decay. And they live longer at high speeds because the physical object is affected by its motion rather than the matter being unaffected while some intangible, subjective concept of "time" is affected instead. I agree on the numbers. The explanation is observably bass-ackwards. The fact that equasions match make no difference. The equasions are fine. The explanation for those equasions are flawed.

Swan, the motion of a car is essentially irrelevant. The difference between frequency of a radio wave traveling at the speed of light vs. the speed of light +/- 60 MPH is pretty negligible. Does your car radio only work if there is a pure vacuum between the source of the signal and your car? How much does the speed of light vary due to the change in mediums between the tower and your car parked in your garage right now? Let me know when you can find a single source of the speed of light being reliably measured without re-emitting it from a stationary object before the measurement's taken.

this is similar to the explanation I was given (although this person is specifying atoms rather than packets of light. I've heard the same explanation for other wave-particles such as light, unless I'm just mixing things up): (it becomes relevant from about 5:30 for the next couple minutes) Unless this is a misrepresentation, it seems that the -suggestion- is that the observation itself changes the projectile from a wave to a particle. It seems more reasonable to attribute this change during the act of measurement to interference based on the measuring process... rather than what seems to be advertised as though measuring the item (observing it) inherently changes it. This variable could be isolated by leaving the camera on, but otherwise disabling it (turning it in a different direction) in order to maintain all variables except the act of measuring.

On my phone and I'm not downloading that pdf file right now.... But when you drop a stone, the force the stone pulls the earth is, in fact, equal to the force the earth pulls the stone. The weight of a pebble in earth's gravity is identicle to the weight of the earth in the pebble's gravity. You may be right about whatever is in the rest of the paper, but don't insult someone's Intelligence with your "go back to school" quip based on an example you object to.... That is definitively correct. You're right that the earth has more mass, thus more inertia, therefore the pebble will be displaced more than the earth will be displaced. I'm sure that was what you were trying to say. But when two objects fall into each other's gravity, they do, in fact, fall at equal speeds, depending on your frame of reference. For a better example, co sided the moon coliding with the earth. Those two bodies are of much more comparable size, so, while the earth pulls the moon at the same rate that the earth pulls all objects, based on its gravitational constant... The moon's gravity will also pull the earth, thus, the two will collide at a speed based on their combined gravity (faster than 32'/second). aaand iI downloaded it anyway. After skimming through it, I'd suggest to the OP to define his terms a bit more clearly... And definitely get a human translator over an online one. I'm seeing some leaps in logic that may just be a miscommunication as to what your formulas represent.

Please tell us he didn't just tell you how to make a cheap backyard stun gun.... Keep in mind, capacitors -can- kill people. Rapid release inherently implies a lot of amperage at once. That's instant death. Stun guns are made "safe" at very high voltage because they have extremely low amperage.

A: they did an episode of this on myth busters. And you can.... If you bounce the bullet through a curved pipe. B:he motion they show on the movie isn't a twisting motion like a curveball... What you said about it coming off on a tangent is correct. As shown, the bullet would go straight. C: a bullet would fire straight in space. Doesn't "always" drop due to gravity. D: on earth, a bullet could curve if it were completely redesigned to be in the shape of a disk. If the bullet's angular momentum were significant enough relative to it's forward momentum, it could act as a frisbee or boomerang and curve. ...so yes. It's possible. Just not with "real bullets" and not like they show on the movie. It has to spin end over end. Airplane terms, think massive yaw rather than roll. Like throwing a playing card.

Light travels at a constant speed (in a vacuum) relative to it's source because that's the speed at which a photon is ejected. For the same reason that objects close to earth all fall at approximately the same speed. The idea of light moving at a constant speed relative to the observer rather than the source is one of those rumors that has been widely accepted with no legitimate proof. Yes, the speed of light coming from a moving object was measured at the predicted speed. This was done with an array of mirrors... Since light was absorbed and re-emitted by the first mirror it hit, they did nothing beyond proving the consistancy of the speed of light between those stationary mirrors. Anyone wishing to dispute this is welcome to provide an example upon which they base their understanding... Where the light measured is not absorbed and re-emitted by a stationary object.

You're on the right path to question time. Keep it up. Just remember, the definition of time has been debated for thousands of years, and people still don't really agree on it's definition. Many believe that time and space don't even exist, but are abstract ways to define what matter is doing. Others believe that time is part of space... A physical, alterable fabric, through which we could travel back and forth. Both have very interesting philosophical implications. A lot of people fall somewhere between those two extremes. As for your intellect... Just recognize that you're smart enough to ask! Anyone can memorize some books and regurgitate the answers their instructor wants to pass a test. Few people are smart enough to ask for the sake of the pursuit of knowledge. Feed your curiosity. Then you'll recognize your potential. And keep in mind that all men are fallible. Confirm things for yourself. Question everything. Just because it's published in a book, doesn't mean opposing viewpoints can't be better.

It's a matter of perspective. How did the sun turn into a black hole? As has been stated the sun's mass stayed the same, but it was compressed to a small enough area, then the gravitational field outside of the area where the surface of the sun currently is would be completely unchanged gravitationally. In that case, no change. Your opponent is right However, that's not the only variable. If, instead, the sun's size remained constant and mass was added to the poi t at which it be ame a black hole the size of the sun... Then you would be right. A black hole the size of the sun will have a -lot- more mass and thus a stronger gravitational field and we would be sucked in very quickly. Here's a way to picture it: X=the distance from the center of the earth to the surface of the earth where you are currently sitting. At the surface, you weigh what you weigh. If you get on a passenger jet, you'll weigh a bit less. At 1x from the surface (2x from the center of the earth), you'll way much less. If the earth were compressed to the size of a pea, it would be dense enough to become a black hole. Objects on the surface of that pea would stand no chance of escaping. But, you could be 1X away from that pea and still experience normal earth gravity as you experience it now. Easy? Btw, I didn't do the math on the pea thing. I just remember a discovery channel special a long time ago that stated that a pea with the mass of the earth would be dense enough. If that scale is wrong.... Find what the right dimension is, and pretend the pea is exactly that big. Don't mess with my illustration, darn it.

I haven't spent much time reading on this particular one, but the topic came up today. I recall hearing that the particle waves (such as light) behaved differently depending on whether or not it was observed by a camera. What I've always wondered is how they isolated that "observation" was the variable changing how the light behavior as opposed to anything else, such as the electromagnetic fields of the running equipment. It seems silly, but did they repeat the experiment with the detectors/cameras running, but facing away or with a blacked out lens? I know they ran the experiment with the camera present but on vs. Off... But "observation" seems a less likely variable than a physical effect of running electronics in the area. Was the experiment repeated with people looking in the direction vs. Looking away (with or without a blind covering the experiment)? It seems that all would be required to isolate the idea that observation was the key variable. I'm looking for specific facts, not an appeal to the concept that we should trust professionals not to overlook obvious holes. Edit to add: I believe it was originally explained to me pertaining to light, but I could very well be mixing up my particle waves.

First, define terms: Time dilation is said to take place due to relative motion. Not the actual forces of acceleration. Thus, two space craft floating by each other in space will each see the other's clock as moving slower, and assume their own clock is moving at the correct rate. Any objections so far?