How Does the Light Barrier Differ from the Doppler Effect?

Maybe it would help if you would lay out the parts of relativity that do make sense to you, so that this one tiny part that you don't understand can be put in context.

When you did your experiment putting the flashlight in the pitcher's hand, what measurements did you do that indicate that you get the same behavior for light as for sound? Where did you physically put the measuring devices?

I'm just telling a story. What differences would you suppose there would be between the flashlight and the air horn?

Just telling a story is kind of weak evidence. If you want me to believe you instead of a century of research, then show me your data. Ifd you can even find a web site that says there is no difference I'll look at that. It is already clear what you think of what I suppose is the difference, so there is no point in me saying it again.

Here is your claim:

The speed of sound is not relative to the person hearing it, but completely independent of the person hearing it.

Light is exactly the opposite. Its speed is not relative to the medium it passes through, but relative to the person seeing it. If you see the light coming from a distant star, it approaches at the speed of light, c. If you travel toward the star at half the speed of light, you might expect to see the light approaching you at 1.5 times the speed of light. But instead the light still approaches you at the speed of light, c. However, the Doppler effect shortens the wavelength, so that it looks bluer than it did before.

Yes the speed of sound is unchanged by the motion of observer or source. It does differ for each medium. The speed of light differs for each medium. In fact, particles can exceed the speed of light in a medium and leave a light boom. This is Cherenkov radiation. But you say light is the opposite. If you travel towards a sound source at half the speed of sound, you'd expect to see the sound approaching you at 1.5 times the speed of sound. But instead the sound still approaches you at the speed of sound. However, the Doppler effect shortens the wavelength. How is sound different than light in this respect? I'm using your own words.

I've already posted the link http://hyperphysics.phy-astr.gsu.edu/hbase/sound/dopp.html but if you google speed of sound and doppler effect you'll see mountains of evidence.

This is for sound only! Did you look at post number one links for the Redshift of light?

Its been there before you even posted your link!

As you know I dont know nothing and lengthy answers are mostly good answers but try again to read what is written there!

Light is behaving a little bit like a wave and therefore the Doppler effect can be applied to light. But light is more. Light is a electromagnetic wave which also behaves like a particle - you heard of Photons, right? This is where there is a huge difference between a Light "wave" and Sound. This is what you need to dig into and understand.

OMG it's like your wandering off onto a completely different topic.

My question was never about what are the differences between light and sound. It was very specific about a particular difference that applied to the Doppler effect and relativity.

Sorry but you are trying to explain relativity on hand of the wave behaviour of light. But nature of light will prevent this unless you consider the the whole thing.

For me this as as if you want to understand turbulent flow from looking at Ohms law.

My last word on this: What you try to understand is RELATIVLY easy.

In response to post #100 by IdeaSmith

Really IdeaSmith, first you heckle me for not accepting the answer, now you're heckling Canary for having the wrong answer I didn't accept. The problem here is not who's right or who's wrong or how sure one is of his position. Everyone has the right to do that without fear that a dsiagreement may offend someone. The problem is the attitude of many of the people on this forum that authoritative opinion should be blindly accepted and that no one has the right to question it. If they do, they should be attacked on a personal level. I'm looking at you IdeaSmith, Canary, usbPort, SolarEagle, Lyn, PassingtoGreeen, HiTekRedNek, StandardsGuy, Kim2012 and NButt. You don't owe me an apology because I can handle trolls but you do owe the forum an apology for turning it into a very closed minded place to post.

The attitude you show here is what is at fault.

Lets start from the beginning:

I just have one question and if it can be answered, I'll understand relativity.

This is a very arrogant way of putting the blame on the forum before you even post the question! It is us, that if we can not explain it to you, that are at fault, if you do not understand relativity. - Get lost!

You come to a Engineering Forum and ask for Physicists #25
But then you ask if there is any Engineers #31

Which one is it?

You repeatedly dismissed arguments that are against your idea without providing any information in favour of your ideas. #27 #40 #30 #35 and more.

You are presumptuous and indeed very stupid to ask a question you already know the answer too! Why did you really come here?

You went as far as in post #26 to simply disregard an answer that was put forward with a lot of effort by brandishing it as it is from somebody who does not understand relativity. While in fact it was you, that did not even try to understand what was being said there! Where was your argument at the time? Why not show us what you know when you have something you know!

I can go on showing you were you failed us but in reality its even worse: you failed yourself!

What on Earth did you do 5 years since you visited us last, announcing that you are not interested in particles and only the wave behaviour is of interest to you. What in heaven are you dreaming about to try to convince yourself and others that Einstein was wrong?

I am not heckling with Canary because I am sure I could have a hell of a nice discussion with him with actual responses containing arguments. If you really think Canary with his posts was offending you, then I can tell you that you have offended him. You do not owe this forum an apology but Canary. I envy all the others that looked through you so quick while I am still quarreling with you. But sometimes I am just slow! In your case I am done!

Bye!

I am sorry for one statement I made, though. I should have never been joking about proving Einstein wrong, I should have been dead serious. Trying to prove existing theories wrong is what science is all about, it tests them, it advances understanding for yourself and maybe, if you're good like Einstein, for the world. I'll never get there, I'm just a novice with a good BS detector.

I'd like to explain why I asked this question. I had been on an inventing forum and saw a call to explain time in 300 words or less. I didn't want to rehash all the cliche and superficial stuff on Wikipedia so I dug deeper. Of course people didn't like this, they said why not just accept what the experts say. Well, I got kicked off that forum after 4 weeks. Anyway, I was really getting stuck on understanding the relativity of simultaneity. I could understand how the ladder paradox worked but did not get the "lightning striking both ends of a train simultaneously" story. I was hung up on why it couldn't be explained by the plain old doppler effect. Now I understand the importance of the frame of reference and, with the help of Jorrie's book, understand the frame that has one observer at both the start and end events. There's still a long way for me to go. Perhaps you guys would like me to repost my posts about time on this forum. From what I've seen, they're bound to make y'all livid and get out the torches and pitchforks.

Thanks for the support. I'm sure I could have a great discussion with you and most everyone else here too (and I have, and I will), and I actually have a question of my own regarding relativity. (Another post.)

In spite of Ralf's insults and stubborn ignorance, I actually kind of feel for him. I want relativity and quantum physics to make sense too. Unlike him, I try to start with the data instead of with my own theories. The data says this is how things behave, and relativity is the mathematical description of that, but it doesn't provide an intuitive explanation of it. As I understand it, string theory may provide an elegant and as yet unprovable theory about how relativity and quantum physics may come together. Michio Kaku's book on hyperspace is a great intro to string theory.

You have put your opinions and ignorance on public display rather permanently. I suggest that if you are able to pick up the basics of relativity from Jorries's book, you come back here and look at what you posted, and see if it doesn't look like insults and stubborn ignorance. And look at what everyone else posted and see how accurate it is.

THEN maybe we can have a conversation without the childishness and self-indulgent pride.

I just wanted an answer to 1 specific question, not a general tutorial on relativity basics. Did you answer the question, no. Did anyone except Jorrie and Troy36, no. Were you even aware of the answer until they answered it? Did I resort to personal attacks (rejecting an opinion is not a personal attack) that others did, maybe eventually. Are these not the facts?

I don't think you understand Jorrie's answer about simultaneity. You certainly don't understand time dilation and space contraction, whether they are big parts or a small parts of relativity. You haven't even budged on the speed of light being constant relative to the observer. You still seem to think that your common sense without any data to use it on is better than Einstein's years of study and a hundred years of research. You said that understanding Jorrie's book could take years.

Why do you think your opinion is interesting to anyone except you?

You have the answer you wanted from Jorrie. Why are you still here? Go read the book and come back. I'll be happy to talk with you then.

Reply to #128

If Jorrie says I didn't understand the responses then I didn't understand the responses and I apologize to everyone for being an ass. I'm not sure if I even understand the Doppler effect if everyone gave me the right answers as they say; the answers seem so contradictory to me.

For me, in relativity, everything is only apparent to the observer, (in relation the observer). I don't think that space or time actually warp.

If the speed of sound would add to the speed of the source, then you could never reach Mach 1, it is the Doppler effect what you perceive as a frequency increase.

The speed of sound doesn't change either: I'm standing at 1000 feet from someone with my gong, he hits it and right after the sound is produced, runs away from me at 750 MPH; I will hear the sound in one second.

If he runs away at the moment when the gong will start vibrating, then I'll never hear it, and in both cases I most likely never get it back.

I wouldn't take the video that you mention as the light speed being captured, he didn't record a single beam but many, many diferent samples.

An amusing thought: If we sent a micro-astronaut on board of his tiny ship (light speed capable of course, instant accel/decel), exactly a the same time that we shoot a laser to a mirror 1 light-year of distance away, when they get back at the same time, two years later, how older will the space traveler find us?.

Regards

We will be 2 years older and your hypothetical astronaut would not have aged, because he would be dead...

BTW, spacetime is not warped by speed, but by gravity. By "warped", we usually mean it has curvature.

-J

I think he meant the astronaut would be exempt from inertia also or in some other means by which he would survive the acceleration.

As I understand it as you approach the speed of light your time would slow to such an extent that you never actually could reach the speed of light. Just like an exponential equation approaches infinity but never quite gets there but in reality you get close enough that time slows enough that it might as well be forever. So for the astronaut's ride, if he instantly accelerated to the speed of light he would look out his window forever and wait to start because the instant he instantly accelerated to light speed time outside would seem to stop...forever.

I think the same thing would happen if you approached a singularity, if you could survive the tidal forces on approach as you get closer time for you would stop and you would never actually get there, but to an outide observer you would collapse into the singularity.

I think it was Hawking who said you could travel time into the future if you went into a close orbit around a singularity and escaped. The intense gravity would slow time and you would leave your orbit and return to where time had not slowed and catch up to a future time.

Drew K

"I think he meant the astronaut would be exempt from inertia also or in some other means by which he would survive the acceleration."

Yes, I suppose hypothetical 'warp drives' could almost do that. "Instant starts" is pushing it out of the realms of reality though.

"As I understand it as you approach the speed of light your time would slow to such an extent that you never actually could reach the speed of light."

To you, your time does not slow down and the acceleration just continuous normally, as long as your engine has fuel. I is just if you measure the speed relative to your starting point that it seems you never reach the speed of light.

"I think the same thing would happen if you approached a singularity, ..."

I don't think so. Only to "outside" observers, which can anyway not 'see' you going into a singularity.

I think you are pushing things a tad too far!

-J

I hate bothering you until I've read your book but this whole thing about acceleration and gravity curving space and how equivalent they are in general relativity; is gravity an actual force or is it just the curvature of space time causing acceleration? Also if light can't escape a black hole which means its speed is reduced to 0, can light speed be slowed by gravity?

"... is gravity an actual force or is it just the curvature of space time causing acceleration?"

In most cases it is a matter of taste whether you view gravity as a force in flat spacetime, causing an acceleration, or as spacetime curvature where there is no force, just movement along spacetime geodesics. I think you will understand it better once you have read through those chapters of the eBook, but to get a little ahead is not a bad thing.

"Also if light can't escape a black hole which means its speed is reduced to 0, can light speed be slowed by gravity?"

You should by now have picked up that the speed of light is 'c' in all inertial frames of reference (IFRs) and that IFRs are the only cases for which c is defined. Now, at the event horizon (EH) of a black hole, the only possible IFR is one that is falling in at c,* so if a photon is 'coming out' at c (relative to that IFR), it will go nowhere...

* Actually, there is no actual reference frame that can observe that IFR as passing the EH at c, because you need a frame that is stationary at the EH, which is not possible. On can get around it by postulating a tiny lab that is held static just above the EH by some super-force. Then a series of observations can be made and mathematically extrapolated to exactly at the EH.

Does this make sense?

-J

*Pushing farther!

Right, to the astronaut, time doesn't seem to change (because that is the observer) but if he were to look outside time would seem to speed up.

I said 'approach' the singularity not penetrate it. As you come in close proximity to a large gravity source time slows down. Einstein theorized this and we proved it by showing clocks move slower on earth than they do in orbit.

Drew K

That is the same thing than one object falling in a black hole look like freezing.

I originally got a bit concerned when you wrote in #134: "... if he instantly accelerated to the speed of light he would look out his window forever and wait to start because the instant he instantly accelerated to light speed time outside would seem to stop...forever."

Now that's pushing it! Since it is a completely unphysical scenario, it does not matter too much, but he would surely know that he has gone 'luminal' - behind him it will be blackness, redshifted out of contention and ahead of him it will be 'infinitely bright', blueshifted to impossibility.

Further, I've got a feeling that you have mixed the properties of the spherical event horizon with the hypothetical central singularity inside: "... if you could survive the tidal forces on approach as you get closer time for you would stop and you would never actually get there, but to an outside observer you would collapse into the singularity."

This sounds more like the event horizon, except that time would not stop for you there - only as viewed by some far-away observer. The central singularity may mean an end of time for the unlucky astronaut, but the outside world can never observe that tragedy - the horizon mercifully hides it all.

Sorry for being somewhat pedantic here, but my concern is that novices may get confused by the way it has developed... :-)

-J

This is beginning to sound like the Infinite Impossibility Drive.

Before-thennow but after-nowlater...

Milliways anyone? Been-there-done-that-tomorrow.

My confusion is quite probable. I am only going on some light reading on gravity, time and light speed.

As I (mis)understand it the closer you get to a deep gravity well time slows down. I don think you would notice because you are measuring that time against yourself. If you could see a clock outside your location it would seem to speed up? Just like if you sit on the earth at sea level and could see a clock in the space station that travels faster time than you do.

To bring our astronaut to a more physical scenario, lets say he has a reaction drive and an magic box that reduces the effect of inertia to near zero so he can accelerate without feeling acceleration. As he leaves the solar system, would he see the planets begin to appear to orbit faster as he approaches the speed of light?

Drew K

"If you could see a clock outside your location it would seem to speed up? Just like if you sit on the earth at sea level and could see a clock in the space station that travels faster time than you do."

Correct for the first part. Almost correct for the second part; the altitude of the ISS causes its clocks to gain time relative to us, but then its speed more than cancels that gain and the ISS crew actually ages slightly slower than we do.

"As he leaves the solar system, would he see the planets begin to appear to orbit faster as he approaches the speed of light?"

Not quite, because if you ignore the acceleration, he would see the planets fly away from him at near c and hence their clocks would appear to be very slow. It is only if he would make a u-turn and head back home that he will find, on arrival, that the Earthlings aged much more than himself.

One-way time dilation is a reciprocal effect - each observer observes the others clock to run slow - but this is not a real effect. It is only in a two-way trip, where one observer expends more energy than the other one, that you find a real difference in elapsed time.

I clapping for you Jorie you describe the twin paradox. Correct

wow...physics is cool and I have so much yet to learn.

Thanks

Drew K

Now I remember why I quit so many years ago, too much to learn. I'm trying to read Jorrie's book and catch up on his forum posts. An interesting coincidence happened today. A question on the science chat forum about Minkowski time asked why the speed of light is no faster or no slower than it is. Then on page 87 of his book he talks about how if the speed of light was infinite, we would live in a purely Newtonian universe with circular orbits and no relativistic effects. That implies the lower the speed of light, the more relativistic the universe would behave. Imagine driving to work and the traffic jam was being caused by speeding? Anyway, it kind of points to an answer of why the speed of light is set at its value. Some process in the universe would break down.

I've moved to torture the science chat forum http://www.sciencechatforum.com/viewtopic.php?f=2&t=24817

Ouch!

What a treatment:

Re: Time, what is it?

by owleye on June 21st, 2013, 9:33 am

...Interestingly, you seem to think you can explain advanced concepts of time and relativity theory to fifth graders. One may wonder whether you are equipped to do so. That sort of skill and talent, I would think, is very rare indeed. You seem to me to have more chutzpah than anything else. So far, you've given me no reason to take you seriously at all.

...

The way I see it you are neither a scientist, nor a philosopher -- merely someone who thinks highly of his own intellect.

James

Don't you like your intelectual spanking?!

Oh yeah the speed of light depends on the electric permittivity and magnetic permeability constants. Finding out why the values of those constants are so important to the functioning of the universe is where the answers lie.

"BTW, spacetime is not warped by speed, but by gravity. By "warped", we usually mean it has curvature."

This has bothered me for a long time because they look so much the same from some angles. If you pump energy into a rocket, it gains speed but it also appears to gain mass! More to the point, hours get longer and measuring rods become shorter with increased speed, just what happens if you enter a gravitational field.

At least, I think that is what happens.

I never understood if the increase in mass and the contraction of space were real phenomena or just a result of the mathematics. Does a particle become flatter and wider with more actual mass as it's accelerated in a collider? What is the nature of this mass that's added to an accelerated proton, is it the gluey condensed energy/mass of a gluon? Or is it strictly the equivalence of the energy pumped into the particle and not more particle? Doesn't the DeBroglie equivalent wavelength contract, thereby giving the particle a higher frequency energy signature and the mathematical appearance that the length of the particle has contracted and the mass itself has increased? Maybe like spacetime, there's a mass-energy behavior that the closer a particle is accelerated to the speed of light, it's mass behaves more like an energy wave with wavelength contraction (instead of space contraction) and greater equivalent energy (instead of more actual mass). This is all just conjecture on my part but maybe someone else says the same thing? Anyway the only real question here is whether mass increase and length contraction are real physical observable phenomena.

"What is the nature of this mass that's added to an accelerated proton, is it the gluey condensed energy/mass of a gluon? Or is it strictly the equivalence of the energy pumped into the particle and not more particle?"

Kinetic energy and momentum are observer dependent quantities and as such not properties of particles. Likewise for Lorentz contraction and 'relativistic mass' - rest-mass is a particle property.

Time dilation can be absolute in certain cases, normally requiring some form of two-way movement in space, e.g. the standard "twins paradox" (which is not a paradox). I will write a little about that in my next Blog post.

-J

So let me see if I've got this straight because I never got this understanding from reading Wikipedia. You're saying that not only time and space are relative to the observer but mass, energy and reality itself is dependent on the observer. An observer going at the same speed as a proton in a collider would see no increase in mass for the proton. So there are as many realities as there are reference frames. All these realities are translated from one to another by relativity to allow a common reality to all.

So in your muon example in the book and on Wiki. The common reality for the muons and the muon detectors on earth are that the muons are making it to the surface in numbers that would be impossible without time dilation. Also in the relativity of simultaneity train and lightning example on Wiki, if you rigged a bomb to an observer that would go off if the lightning strikes on both ends of the train were not detected simultaneously, there would be no reality where one observer would see the other blow up if that observer didn't actually blow up because relativity saved him.

I think you are getting there. Take note of some pointers though.

"You're saying that not only time and space are relative to the observer but mass, energy and reality itself is dependent on the observer."

Rest mass is not dependent on any observer and we are no longer talking about 'moving mass' or 'relativistic mass', but rather just about relativistic momentum or energy. When we say 'mass', we mean 'rest mass'. The old way of saying things have caused a lot of confusion.

You must also be careful to not confuse observers that 'see' events simultaneously and observers that measure events to be simultaneously. Relativistic simultaneity is determined by clocks synchronized in each inertial frame. Simultaneous means the events have the same time stamp in that frame.

The best way of determining the time-stamp for an event is by having an observer with a synchronized clock right where the event happens. However, when the observers is at some distance, the coordinate time of the event can be calculated if we know the distance to it...

-J

Nope I was wandering off again. I looked up relativistic mass on Wiki and it appears to be nothing. The best quote on there, it makes increase of energy of an object with velocity or momentum appear to be connected with some change in internal structure of the object. In reality, the increase of energy with velocity originates not in the object but in the geometric properties of spacetime itself.

So reality is not observer dependent. Reality is a series of events in time but how we perceive time differently from our frame of reference has no effect on the events themselves.

Even that Wiki quote is a little dubious, e.g. "In reality, the increase of energy with velocity originates not in the object but in the geometric properties of spacetime itself."

It is more "in the eye of the beholder" than in spacetime itself. Granted, it is a property of spacetime that makes observers measure a relativistic momentum which is larger than what Newton would have predicted, because it is multiplied by the relativistic gamma, i.e. momentum p = γm₀v = m₀v/√(1-v²/c²).

-J

I must be very careful of what I say because I still don't get the nuances and am brainwashed by by science journalists' interpretations of relativity. So no actual mass, as in matter, is added to a particle in a collider, it's just mass equivalent to the energy that's imparted on the particle according to E=mc2. Likewise the Lorentz transformation "is the length of the object contracting when measured by subtracting the simultaneously measured distances of both ends of the object" according to Wiki. So it's like the ladder paradox and has way more to do with relativity of simultaneity than with a real physical length contraction (unless it's space, from an observer's relatively stationary reference frame, that contracts and the object just follows along with that).

"So no actual mass, as in matter, is added to a particle in a collider, it's just mass equivalent to the energy that's imparted on the particle according to E=mc². "

Yes, but you don't need to think "mass equivalent to the energy" at all. It is just momentum and total energy that increase; in fact it is the De Broglie wavelength of the particle that is shortened by the addition of kinetic energy. The relativistic energy of a moving particle is given by

E = √[p² + m²₀] c² = √[(h/λ)² + m²₀] c²

where p is the momentum, m₀is the rest mass, λ the de Broglie wavelength of the particle and h is the Planck constant.

-J

Hi Jorie mi name is Javier I have been following this almost from the beginning and I understand the theories of Albert. I was lately working with an idea that from my point of view look really interesting. The Idea is: If we see the universe using the Albert theories and we see the time like relative part of it. And we get the time like getting shorter from the past to the future it will give us a Doppler effect like the one they are looking right now and that will mean the universe is no expanding like Albert said. This means that the universe has no dark energy or matter and will show to an observer like spending that will be only and optical illusion. And the observable universe will be between 14.5 to 16.5 billion years old. If time is coming like waves in the future it will show like the universe is expanding in an accelerate maner and then it will be shrinking to restart the cycle. The problem right now is that the astronomers are using the single math to calculate thing happening In the universe and they are changed because we are looking at them back in the past and they are long distances and times that we see them with a relativity distortion. The only way to be sure were thing are to calculate them with relativity math. If all this is true the light coming from the past like is happening will keep the speed of C but the effect in the frequency will be of Doppler Effect that will explain why we are looking de red shift in our telescopes and will explain the dark energy and matter.

If I have some redactions problems is because English is my second language and I am lower than High School on English. My language is Spanish and I am like 4 year college on it. If you want to ask me question about my idea let me now. It was nice to tell hello to you Jorie.

Javier

If perplexity is the beginning of knowledge I'm still spinning my wheels trying to get out of the perplexity stage. So far we have 3 things that are waves: light, sound and matter (as in wave-particle duality). They all behave differently. Light speed is unchanged whether you're moving with the source or relative to the source. Sound speed is unchanged if you're moving relative to the source but not if you're moving with the source? (Still don't quite get that because if you're driving in a jet at mach 2 with the radio blasting, you can still hear the radio but the plane beside you wouldn't hear it.) The observed speed of matter (even though it has a characteristic wavelength) is dependent on the speed of the source and observer; no doppler effect. Even though matter and energy can be transmuted, what makes them so different. What is the significance of the disconnect between the wave frequency of matter and that of energy. I'm still lost.

Sorry, I keep forgetting about the speed of sound relative to its medium. The air inside jet 1 is not moving but between the planes the relative speed is mach 2.

Let say that we are in one place and we send something a the speed c that objet is going to be reduce in the direction of the movement the closes of the c speed de shorter it is that mean the amount of mass is going to be close to the infinite and at the same time it need more time to travel because the shorter it is it take longer to travel the same distance in our plane and that mean his clock in it speed is going to be slower. The amount of energy to speed that objet in our place is going to be infinite. It is little hard to visualize this but the other day I find a geometrical explanation of this and it is logical Albert visualize in a very nice way and that was hard because it was the first time

Javier, if you have read and understood (as a minimum) the exchanges between ralfcis and myself, you probably would not have had to ask this question. Feel free to ask more question related to those discussions. It is unnecessary to entertain an object that becomes "flattened" and hence more dense at relativistic relative speeds. It is just a length measurement issue (how clocks are synchronized) between frames and not a property of the object.

Please try to get that straight first...

-J

Yes I know that I am only trying to make him to understand that things don't change in your own frame but the thing moving look like it was change. In the other hand if you are in the moving object your frame is no going to change too because the observer see things no changing in its own frame and the speed of the other frame is going to be the one moving in the c speed and at the same time the other frame is going to look like infinite mass

"... the observer see things no changing in its own frame and the speed of the other frame is going to be the one moving in the c speed and at the same time the other frame is going to look like infinite mass"

I'm trying to get everyone off the notion of "increase in mass" or "relativistic mass" at relativistic speeds. Although not strictly wrong, it can be sooo confusing to beginners. Rather stick to mass as simply rest mass, because that is easily measurable by any scientific balancing scale. The rest is relative momentum due to the relative speed: p = γm₀v = m₀v/√(1-v²/c²), or total energy: E = √[p² + m²₀] c²

-J

"The observed speed of matter (even though it has a characteristic wavelength) is dependent on the speed of the source and observer; no doppler effect."

As you could infer from my prior reply, there is a connect between speed and de Broglie wavelength of the particle. But, we normally do not consider that as Doppler shift, except as redshift in certain cases when we do Cosmology, as you can check under the link. For this thread though, speed and momentum are observer dependent attributes of particles and rest mass is an absolute property.

I'm glad you have later noticed your error in thinking about sound waves. It is the medium-less versus the medium-dependent propagation issue ...

-J

That's the crux of the matter. I didn't understand the Michelson-Morley experiment because I had to unlearn all that was stuck in my head. It had nothing to do with incoming starlight or the resulting doppler effect. It had to do with my radio in a jet plane example.

The inferometer had its own lightsource and it was designed to detect if movement through the aether medium would push the lightbeam sideways as movement through air would push a perpendicular sound beam sideways. A sound beam travelling sideways in the cockpit of a fast jet would bounce back and hit your ear without any deflection because the air in the cockpit is stationary in relation to the sound beam. But if you cut a hole in the jet so the soundbeam could reach the other jet, the fast moving air between the jets would just sweep the sound away.

Now if the aether clung to the surface of the earth like the atmosphere or the air in the jet cabin, then the Michelson-Morley experiment would have detected no movement of the earth with respect to the aether. But they somehow discounted that possibility and concluded there was no medium for light because the inferometer detected no sideways bending of the light beam that would have occurred if it had been moving through a medium.

This leads me back again to my original question. All that the Michelson -Morley experiment should have concluded was that light does not have a medium. I assume if you shone light through a glass rod, light could be moved by moving the rod but it could never reach the speed of light in a vacuum as a result of that extra movement. That would mean light behaves quite differently in a medium than sound does because the speed of the medium can be added to the speed of sound so that the sound can exceed the speed of sound to an outside observer.

The conclusion that Einstein drew seems like quite a jump to me. I read further that Lorentz length contraction explained the Michelson -Morley results by saying the light speed in the forward direction was equal to the lightspeed in the sideways direction because the length of the path it had to travel was shortened in the forward direction. After Lorentz said that, Einstein was able to come up with relativity. I'm missing some key dots that were connected here. He was somehow able to see the speed of light was inviolate and as a result, space and time were not.

"The conclusion that Einstein drew seems like quite a jump to me. I read further that Lorentz length contraction explained the Michelson -Morley results by saying the light speed in the forward direction was equal to the lightspeed in the sideways direction because the length of the path it had to travel was shortened in the forward direction. After Lorentz said that, Einstein was able to come up with relativity."

Yes, Einstein made a 'jump' that was based on his own insights on how inertial frames behave and according to his own 'testimony' was not directly influenced by Michelson-Morley or Lorentz. He surely knew about those results, but his abolishment of the aether was novel for his time. Note that he reportedly said (paraphrased) that if there is an aether, but nature conspires against us so that we cannot detect it, then we can just as well forget about it.

Einstein and Lorentz differed in that Lorentz retained the aether and postulated a physical contraction at atom level, while Einstein's Lorentz contraction is just an observer dependent effect, with each inertial observer having an own private aether, that does not exist anyway! (My own abstraction that some may disagree with - it is essentially the 'private simultaneity' of each observer). More technically, each inertial observer has her own "4-space", as I touched upon in this Blog reply.

-J

Wiki has conflicting testimony. At times they agree that Michelson did not directly influence Einstein but they do say, at times, that Michelson influenced Lorentz and that Lorentz influenced Einstein. I've also read the aberration of light is what influenced Einstein and also that nothing except his thought experiment of trying to catch up with a light beam to view it sideways was the only thing that influenced him. Hence, all my questions about the Raskal film of a light pulse which does not agree with Einstein's thought experiment. I'm just trying to understand Einstein's eureka moment which would maybe tie all these conflicting facts together in my own mind. What would possess a guy to conclude that light not having a medium and having constant speed in all reference frames meant that time and space was different for each observer in order to preserve a common translatable reality for all observers.

Wiki also can't agree whether Lorentz contraction is a real physical thing, (they quote actual experimental observations) or if it occurs as equivalent Debroglie wavelength contraction at the quantum level or that it's purely mathematical in nature.

Let me rephrase that last question. What would lead a guy to conclude that light not having a medium meant that light would have the same speed for all inertial frames of reference and that that meant time and space were different for each observer?

I think Einstein was largely influenced by Maxwell's equations governing electromagnetism and the constant c that appears in it. He realized that Galileo's relativity of 1632 (you cannot detect uniform motion inside a closed container or ship) must mean that you should not be able to detect a variance in the speed of light either. This meant that the Galilean/Newtonian aether should not be detectable. Through this and other thoughts, he came to the concept of the relativity of simultaneity and with it the realization that the Lorentz transformations must hold between observers in uniform relative motion.

Thanks.

Apology accepted. Now go read that book so we can have a decent conversation.

I cant decide if this is is the definition of you...

ig·no·rant

/ˈignərənt/

Or if this is better...I think at least most of the trolls actually know what they are talking about and just are hateful little people who like aggrivation...I don't know if I am ready to give you that kind of credit.

Drew K

Hmmm, I guess that's mission accomplished if that was indeed my mission.

Well, I missed the opportunity to answer earlier because of the time difference (I live in Europe) so I had to read first where the discussion arrived since yesterday.

I think I can best answer to your question by changing a bit the scenario: consider a fixed sound source (it can be a standing truck if you want) that is sending short horn warnings (sound pulses). And consider not just one observer but two, both moving with the same speed and in the same direction - belonging to the same inertial system. Consider first that they are moving towards the truck (the sound source), the second observer being behind the first one at a certain distance. The truck horn releases a sound pulse and both observers note the moment of time the pulse arrived at them. If they consider the distance between them and the time difference it took to the pulse to reach each of them they will say that the speed of the pulse was greater than if they didn't move. Of course, if they move away from the truck, the same experiment will give the result that the speed of the pulse is smaller. And if they move very close to the speed of sound (and if they have a way to see the sound waves) they can even see the pulse passing slowly by them. But if they replace the sound source with a light source and they try the same experiments as above the result will be the same speed of the light pulse ("c") regardless of their speed (even very close to "c")!! That's why relativity had to appear and explain how is this possible. But, as I told you before, the new set of formulas and the behaviour of anything moving very fast (close to "c") is contrary to our common sense and leads to an effort to understand what is happening "in fact" (as compared to Newton's physics) to have such strange results.

You don't want answers. You just want to argue.

Here's an idea.

START YOUR OWN FORUM and only let smart people, just like you, in.

1. How to Start Your Own Forum With Forumotion: 5 Steps - wikiHow
1. Yuku: Start your own free forum, social network, social community, or ...

1. 5 Great Sites To Create Your Own Forum - MakeUseOf

I anxiously look forward to the time when you start your own forum.

We've moved on lyn. Comedy is all about timing though.

But he is funny, you are not!

What's funny is the rating system here. Off-topic? That's pretty much a given for most posts and should not mean it's not a good answer. Even wrong answers are considered good here.

Good answer should be split into "I don't know but it sounds good", "I don't know but this guy's been here a long time", "I don't know but Wiki's been referenced", and "I like cheese."

The simplest answer I see to this question is The Doppler Effect and the Light Barrier are two different things, one is the fastest speed the light can travel and the other is the frequency of the light waves. One will have no effect in the other one. Simple like this

Javier Trejo

Could we say then that the Doppler effect is based on the behaviour of light as a wave?

While the speed is related to mass which is the property of particles!

Interesting thought!

I like it!

It's an interesting thought in that why should pitching a baseball off the back of a moving flatbed truck add forward velocity to the baseball while blaring an air horn not add any velocity to the speed of sound a stationary observer would hear. Other than that, your idea that speed is related to particles would contradict relativity in that the speed of the particles (baseballs) and hence the speed of light would increase as a result of the forward movement of the source of those particles ie a flashlight turned on on the back of that flatbed truck. However, writing way more than 3 lines to your idea would have given it some weight and therefore would have made it true on this forum.

I meant to write a post on this thread about a Nerd Troll...but I got distracted by something shiny (work and other less annoying threads). I should have made that comment and possibly saved some of us the frustration of dealing with this stupid troll.

Actually, I am kinda glad I didnt because I read the single best explanation I have seen on Einstein relativity. Thanks Canary!

Drew K

It's amazing how much one can learn when one loses the fear of looking stupid. The opposite is also true.

When I saw the direction this forum was headed,I ceased to contribute, and am surprised it has gone on this long.I just dropped in because of so many reply notices in my mailbox.

It is obvious to even the least initiated that Ralfis is a fool, and I do not suffer fools lightly.A sincere curiosity,when accompanied by genuine introspective thought and diligent study is never considered foolish, however when any knowledge contrary to pre formed ideas is ridiculed, and shot down, there is little hope of progress or learning.

You have my pity,Ralfis, but not my respect.Perhaps someday you will advance to the point of realizing your mistakes.If not, you will have learned nothing,and will remain ignorant for the rest of your life.

"When a wise man contends with a fool, it is impossible to tell them apart."

And with that I will bid you adieu.

May you live long, learn, and prosper.

Thanks for showing me what my potential future looks like. I will steer clear of the path you have taken. Maybe you just need some more coffee? I wish you a speedy recovery.

It is a little hard for somebody that doesn't know about something to ask very smart question. And there it is when the person that knows about should use very wise answers. The fault is not the one following. The fault is from the person that guide and know the road ahead.