My problem with einstein

[phillip1882]

everyone's heard of the famous thought experiment.

a car traveling near the speed of light tward a distant wall turns on its head lights.

it takes the light the same amount of time to hit the wall as if the car were standing still, or even going in reverse. thus it must be time that's being minpulated somehow.

here's my problem with that idea.

a car traveling near the spead of sound tward a distant wall honks its horn.

it takes the sound the same amount of time to hit that distant wall as if the car were standing still or even going in reverse. yet we cannot conclude the same thing, that time is being minpulated somehow.

so... can anyone explain to me the flaw with this logic?

[Tormod]

so... can anyone explain to me the flaw with this logic?

 

I'll take three guesses...

 

1) It's not about relativity (sound is the motion of air waves, not the motion of electromagnetic waves like light)

2) A car traveling at (or even near) the speed of light would have to be in vacuum - thus the horn would not make a sound and thus the sound cannot travel at all

3) Einstein didn't have a car back before he published his theory of relativity :shrug:

 

By the way: It's not time as such that gives. It's space.

[phillip1882]

1) It's not about relativity (sound is the motion of air waves, not the motion of electromagnetic waves like light)

that's certainly true but i don't see how it helps your point. for example, just as with light. no matter how much energy you put behind a sound wave, the sound wave still travels at the speed of sound.

2) A car traveling at (or even near) the speed of light would have to be in vacuum - thus the horn would not make a sound and thus the sound cannot travel at all.

once agian i don't see how this helps your point. visable light can't travel through a solid wall, but a sound wave can do so to some degree.

3) Einstein didn't have a car back before he published his theory of relativity.

but there wereplenty of cars around and eistein must have known about sound having a similar property.

[Tormod]

You miss my point.

 

Let me explain:

 

1) Your problem is not with Einstein, because you are not discussing relativity. You can't compare light waves and sound waves in your example. You are correct in that the speed of sound can't be "pushed", but there is no set limit to the speed of sound. You can travel at many times the speed of sound. The speed of sound varies greatly depending on what it travels through. Light has a set limit and it is (as far as we know) impossible to break that barrier.

 

2) My point is again that you can't compare the two. Sound needs a medium to travel through, or more correctly sound is basically a medium in motion - air, earth, rock etc). Sound is not energy but the representation of energy. Light is however pure energy and thus does not need a medium to travel through. In fact, any medium will slow or stop light.

 

3) The third guess was a joke, thus the laughing smilie ( :shrug: ).

 

My final note about *space* and not *time* yielding was not a joke, however. Einstein realized that for the speed of light to be finite to all observers in all reference frames, then obviously *something* had to give. It's not time that gives. It is space. Since space and time are interlinked, this is a bit convoluted.

 

I highly recommend reading some popularized accounts of relativity, for example these:

 

Amazon.com: E=mc2: A Biography of the World's Most Famous Equation: David Bodanis, Simon Singh: Books http://www.amazon.com/mc2-Biography-Worlds-Famous-Equation/dp/B001FWXRAC/

 

Amazon.com: Einstein's Cosmos: How Albert Einstein's Vision Transformed Our Understanding of Space and Time (Great Discoveries): Michio Kaku: Books http://www.amazon.com/Einsteins-Cosmos-Transformed-Understanding-Discoveries/dp/0393327000/

 

Or get it straight from the horse's mouth (not too easy to read):

 

Amazon.com: Relativity: The Special and the General Theory (Penguin Classics): Albert Einstein, Nigel Calder: Books http://www.amazon.com/Relativity-Special-General-Penguin-Classics/dp/0143039822/

[Janus]

everyone's heard of the famous thought experiment.

a car traveling near the speed of light tward a distant wall turns on its head lights.

it takes the light the same amount of time to hit the wall as if the car were standing still, or even going in reverse. thus it must be time that's being minpulated somehow.

here's my problem with that idea.

a car traveling near the spead of sound tward a distant wall honks its horn.

it takes the sound the same amount of time to hit that distant wall as if the car were standing still or even going in reverse. yet we cannot conclude the same thing, that time is being minpulated somehow.

so... can anyone explain to me the flaw with this logic?

 

Okay, here's the thing with light, the time it takes for light to hit the wall doesn't change for different velocities of the car, as measured by someone who's motionless with respect to the wall. However, to someone in the car, the amount of time does change with a change in relative velocity with respect to the wall.

 

Here's why: The speed of light is the same for everyone. Meaning as measured relative to themselves, everyone measures light traveling at the same speed. So if I'm sitting in the car and turn on my lights, I see the light traveling away from me at c. At the same time, I see the wall coming towards me at near c. The wall and light meet at near the half the distance that the wall was when I turned the lights on. If I am heading away from the wall, the light leaves me at c, and the wall is receding from me at near c. The light has to "chase down" the wall and doesn't reach it until the wall is some much greater distance away from me than it was when I turned on my lights.

 

Now for sound. Sound travels at the same speed relative to the medium through which it is traveling. Thus when I, in my car honk my horn while driving towards the wall at near the speed of sound, I see the sound travel at a fixed speed relative to the air through which I am driving. Thus the speed of the sound relative to me is equal to the difference between the speed I am driving and the speed of sound through air. The combination of the slower relative to me speed of sound and the near the speed of sound velocity of the wall toward me combine to make the time I measure for the sound to hit the wall to be the same as someone measured by someone standing at the wall, or as measured by me if standing still or moving away from the wall.

 

Thus for light, the observer by the wall will always measure the same time regardless of the velocity of the car, but the person in the car will measure different times for different velocities, While for sound, both the person by the wall and the one in the car measure the same time regardless of the velocity of the car.

[phillip1882]

tormod

 

"You can't compare light waves and sound waves in your example."

there seems to be a fairly strong correlation so i don't see why not.

You are correct in that the speed of sound can't be "pushed", but there is no set limit to the speed of sound.

yes there is, else it could be pushed faster.

"The speed of sound varies greatly depending on what it travels through."

thats true with light as well, as you point out in your second paragraph.

 

"Light is however pure energy and thus does not need a medium to travel through."

i assure light is not pure energy, if it were we wouldn't be able to detect it in any way, that is there is a physical part to light that we call the photon.

 

janus

"The speed of light is the same for everyone. Meaning as measured relative to themselves, everyone measures light traveling at the same speed. So if I'm sitting in the car and turn on my lights, I see the light traveling away from me at c. At the same time, I see the wall coming towards me at near c. The wall and light meet at near the half the distance that the wall was when I turned the lights on. If I am heading away from the wall, the light leaves me at c, and the wall is receding from me at near c. The light has to "chase down" the wall and doesn't reach it until the wall is some much greater distance away from me than it was when I turned on my lights."

this is all true with sound as well. if i was traveling near the speed of sound and honked my horn, by the time the sound wave hit the wall i would be very close to the wall. if i were stoped and honked my horn, then i would be a different distance from the wall. and if i were going in reverse, once agian i would be a different distance.

 

"Now for sound. Sound travels at the same speed relative to the medium through which it is traveling. Thus when I, in my car honk my horn while driving towards the wall at near the speed of sound, I see the sound travel at a fixed speed relative to the air through which I am driving. Thus the speed of the sound relative to me is equal to the difference between the speed I am driving and the speed of sound through air. The combination of the slower relative to me speed of sound and the near the speed of sound velocity of the wall toward me combine to make the time I measure for the sound to hit the wall to be the same as someone measured by someone standing at the wall, or as measured by me if standing still or moving away from the wall. "

once again this is all true for light as well. for example inamge an astronaut in a space station that's orditing the earth many times the speed of sound. do you think he would have to scream to be heard to his buddy next to him? of course not. would the light inside the space ship be traveling any faster? of course not. once again i dont see how oyur argument proves time dilation.

[belovelife]

you know light needs a medium (space-time) to travel through also

(so theoretically light would travel at different speeds in different instances of space-time)

 

 

also have you heard of the cloaking technology being developed, it conciels about a few millimeters of mater by supposedy bending light

hence creating the effect of light being on either side of the object

looking like the object is not there

now the situation is

 

it takes alot of energy

you cannot see the object

 

now are we bending light

or shrinking space time on a minimal level to

give the illusion of light bending?

[belovelife]

tormod

 

 

"Light is however pure energy and thus does not need a medium to travel through."

i assure light is not pure energy, if it were we wouldn't be able to detect it in any way, that is there is a physical part to light that we call the photon.

 

 

light would need space time to tracel through

 

a photon can be transduced to an electron depending on the efficiency of the transducer

 

now i ponder, in different mean levels of space time density on a multiverse level, would light be similar to sound, in which case it would interact differently on different levels of the concept we call space-time?

 

now if so, then we have a dynamic accociated with sound, but light being the particle "waiving" medium. then if, according to m-theory, in the mutiverse, the resonace of what we deem a spectrum of particles moving at the speed of light, could actually resonate in different dimentions similar to sound traveling through different mediums

 

this would be able to be measured in the instance of the present cloaking teck being developed, by the amount of energy in relation to the amount of light being bent

 

or the amount of space-time being shrunk/expanded

 

basically, if light can be bent, or space-time can be manipulated, then it can be measured by the amount of this reaction occuring

 

if you take into consideration the actual reaction of light bend/ or space-time movement

then it would be obvious to realize that when space time is bent, then it would be its own unique version of space-time

 

if you bend space-time and create a different path (more dense in shrinking)

then it would be its own individual vecor on space-time

 

either that or, as you create a new vector for light in space-time you change the speed or the light, in which case you either sped it up or slow it down, either way you manipulate the actual vector of light in space-time thus allowing for a difference in the actual spped of light

 

unless you are bending space time, then you would just be creating a new vector

[belovelife]

also

 

taking into consideration the instance of a nutreno

 

it knoks off the nuetron from the nucleus of a heavy water molecule

(from the hydrogen)

 

then (if you look up belovelife's universal unification theory)

it would insinuate the the "nutreno" would be aeither in a stable state being able to travel through space time in a unique vecor, thus allowing for instant communication across the universe, but still interacting with space-time in the respect that it adds a cause to the reality that we observe

 

basically, if you have a unique vector in space-time, then you have a different path, now when the impetali process occurs, it could replace the current process at a different measured level in comparison the the current measured level of space-time impetali process, in which case, if you could

 

observe

record

transmit

 

on this philosophy

then you could desighn a dynamic process for intergalactic communication

throught the use of aeither

 

but this is totally based on belovelife's unification theorom

[Tormod]

belovelife,

 

your posts sound a bit like rambling. The neutrino has no mass and cannot know anything out of a nuclear core.

 

While we say that sound needs a medium to manifest itself (sound is just motion in that medium), spacetime cannot be considered a "medium through which light travels". Spacetime exists throughout the universe we live in - AFAIK it is the very definition of our universe - and is not a "medium" as such.

[Tormod]

You can't compare light waves and sound waves in your example.

there seems to be a fairly strong correlation so i don't see why not.

 

they are two completely different entities, like I have already pointed out. you can compare them for the cause of studying waves but that doesn't mean they behave similarly. Light has a particle-wave duality which in no way is present in sound. There is no "sound particle" (maybe we should invent it and call it the audion).

 

You are correct in that the speed of sound can't be "pushed", but there is no set limit to the speed of sound.

yes there is, else it could be pushed faster.

 

I think the basic problem here is that you are comparing apples and oranges. Light is produced in a completely different way than sound, they travel differently, they are absorbed in different ways and they are different kinds of energy.

 

I can produce sound by simply clapping my hands. That is nothing but air being set in motion. I can also create sound by hitting a rock. This creates two kinds of waves - a sound wave in air and a sound wave in rock. These are different. The speed of light depends on the medium it travels through.

 

Speed of sound - Wikipedia, the free encyclopedia

 

I cannot however produce a light wave without a device like a flashlight or led or some similar light emitting device. The speed of light in various mediums can be measured (water slows light slightly, observed as refraction if you're standing above the surface of a lake for example).

 

The speed of sound varies greatly depending on what it travels through.

thats true with light as well, as you point out in your second paragraph.

 

True. But my point, as built upon above, is that sound waves are motions in a medium, whereas light waves are not dependant on a medium. They can travel through vacuum (something sound can't, since it must have a medium). Light can also through air, glass, water etc, but not through, for example, rock unless it is transparent (like quartz).

 

Light is however pure energy and thus does not need a medium to travel through.

i assure light is not pure energy, if it were we wouldn't be able to detect it in any way, that is there is a physical part to light that we call the photon.

 

The photon is the carrier of the electromagnetic force and can easily be detected using (for example) solar panels. This is why I recommended you the books above - the particle/wave duality of light means that light is a particle when it interacts with something, but travels as a wave.

 

once again this is all true for light as well. for example inamge an astronaut in a space station that's orditing the earth many times the speed of sound. do you think he would have to scream to be heard to his buddy next to him? of course not. would the light inside the space ship be traveling any faster? of course not. once again i dont see how oyur argument proves time dilation.

 

There is no "speed of sound" around the space station since it is outside a medium through which sound can travel. The speed of sound in the air inside the space station is a result of the pressurised air and can be measured to be similar to that of the surface of the Earth (or slightly different).

 

Light inside the space station cannot move faster than other light since light always travel at a maximum of c regardless of where you see it from.

[Qfwfq]

Allow me to take a guess, too. From what you say:

it takes the light the same amount of time to hit the wall as if the car were standing still, or even going in reverse.

 

There isn't really a way to deduce:

thus it must be time that's being minpulated somehow.

 

Indeed, as Janus points out, the "same amount of time" only goes for those at rest with the wall (and certainly isn't a consequence of SR anyway).

 

The velocity of the car doesn't change the speed of the emitted light nor of the sound. The difference is the speed of each of these as measured form the car.

[CraigD]

… thus it must be time that's being minpulated somehow.

here's my problem with that idea.

...

so... can anyone explain to me the flaw with this logic?

In physics, whether using special relativity or not, it’s important to precisely define what you’re talking about. We can’t ascribe much meaning to phrases like “time being manipulated”, so need to keep things in terms we can understand, such as the duration of specific events. When we’re using special relativity, we have to define the relative motion of the inertial frames in which quantities such as duration are being measured.

 

Keeping this in mind, let’s look at Phillip’s first example

a car traveling near the speed of light tward a distant wall turns on its head lights.

it takes the light the same amount of time to hit the wall as if the car were standing still, or even going in reverse.

This is true only as measured by an observer stationary with respect to the wall. In this case, the duration [math]T[/math] it takes the car’s headlights to reach the wall distance [math]D[/math] away from the car is [math]T=\frac{n D}{c}[/math], where [math]c[/math] is the speed of light in vacuum, and [math]n[/math] the refractive index of the medium between the car and the wall. For the sake of simplicity, it’s nice to assume a vacuum between the car and the wall, as [math]n=1[/math] for a vacuum. In air under typical conditions (air, temperature 0 C, pressure 1 atm, wavelength of light 589 nm, yellow) [math]n \dot= 1.000293[/math]. Not only does it take light traveling through air longer to reach the wall, unless the light is of a single wavelength, such as produced by a laser, its different colored parts will reach the wall at slightly different times. So, let’s assume for examples concerning light that the car and wall are in a vacuum, in which case [math]T=\frac{D}{c}[/math]

 

As measured by an observer stationary with respect to the car traveling directly toward or away from the wall at speed [math]V[/math], the distance to the wall [math]D_1[/math] and the duration light takes to reach it [math]T_1[/math] are different than the [math]D[/math] and [math]T[/math] measured by the observer stationary with respect to the wall, due to length contraction. [math]D_1 = D \sqrt{1 -\left( \frac{V}{c} \right)^2}[/math], and [math]T_1 = \frac{D_1}{c} = T \sqrt{1 -\left( \frac{V}{c} \right)^2}[/math].

 

Thus, if [math]V>0[/math], [math]T_1<T[/math]. If the two observers compare their measured times – specifically how they can measure these times is more complicated, and left for a separate discussion – they find they’re different as described above. The reason and description of this difference is called time dilation.

 

Now let’s consider Phillip's second example

a car traveling near the spead of sound tward a distant wall honks its horn.

it takes the sound the same amount of time to hit that distant wall as if the car were standing still or even going in reverse. yet we cannot conclude the same thing, that time is being minpulated somehow.

Yes, we must conclude the same thing, that time dilation occurs just as with the previous example. The two observers will experience time dilation when comparing a duration measured by any means that would result in [math]T_1 = T[/math] when [math]V=0[/math], whether it be measurements of mechanical or electronic clocks, the ageing of human bodies, or the travel times of light or sound.

 

Beginning students of special relativity may want to stop with the above explanations, as gaining an intuitive understanding of the theory is not always aided by considering complicated questions before the explanation of simpler ones has had time to “sink in”. Once you’ve learned the concepts and formulae of SR, you’ll usually find that you’re able to apply them to resolve what initially seemed to be impossible paradoxes and contradictions arising from the theory.

[phillip1882]

Yes, we must conclude the same thing, that time dilation occurs just as with the previous example.

umm okay i see about 10 things wrong with coming to that conclusion. firslty, if i asked 10 scientists if they thought sound waves dilate time, i would bank on at least 9 of them saying no. diregarding that the speed of light is much faster than the speed of sound, they cannot both dilate time, else there wouldn't be a faster speed. also, SR says nothing about sound only light.

[phillip1882]

"you're compareing apples and oranges"

 

apples and oranges are both fruit. the both have seeds in the center, they are both eaten by alot of people.

if i am running tward a distant wall at a speed of 20 miles an hour and throw an apple at 30 miles in a hour tward a wall, the apple would be traveling at 50 miles an hour tward the distant wall. if i were stopped, it would be going 30 miles an hour. in reverse, 10 miles an hour. i can substitute an ornage in for an apple as well and get the same result.

 

sound == light i agree. but if i get a similar result i should reach a similar conclusion.

[Tormod]

sound == light i agree. but if i get a similar result i should reach a similar conclusion.

 

Your results are not similar. They just appear to be. That's what you're not seeing.

[JMJones0424]

if i am running tward a distant wall at a speed of 20 miles an hour and throw an apple at 30 miles in a hour tward a wall, the apple would be traveling at 50 miles an hour tward the distant wall. if i were stopped, it would be going 30 miles an hour. in reverse, 10 miles an hour. i can substitute an ornage in for an apple as well and get the same result.

 

Light is not thrown, it is emitted at a velocity that is constant in a vacuum, regardless of the relative velocity of the emitter. The analogy you are creating is invalid.