Thread: Matter Waves and Us

I believe that the speed of an object is unchanged by a persons perception of said object
although different perceptions of that same objects speed can be had simultaneously
if viewed under different circumstances by different observers.
Albert E. used the example of a flying bird viewed from a passenger on a moving train also being viewed by a stationary bystander on the ground. Each subjects perception of
each others speed is directly influenced by their own position . The bird sees the train to
be moving slightly faster than itself while the subject on the ground perceives the same
train to be rushing past quickly. Neither perception actually changes the speed of the train.

I never went to college so this is based on my understanding of what I've read on my own. If someone feels this is an incorrect example please let me know so I can understand better.

I highly recommend: The Dancing Wu LI Masters by Gary Zukov.

Originally posted by R.Carter
I believe that the speed of an object is unchanged by a persons perception of said object
although different perceptions of that same objects speed can be had simultaneously
if viewed under different circumstances by different observers.
Albert E. used the example of a flying bird viewed from a passenger on a moving train also being viewed by a stationary bystander on the ground. Each subjects perception of
each others speed is directly influenced by their own position . The bird sees the train to *
be moving slightly faster than itself while the subject on the ground perceives the same
train to be rushing past quickly. Neither perception actually changes the speed of the train.

I never went to college so this is based on my understanding of what I've read on my own. If someone feels this is an incorrect example please let me know so I can understand better.

That's what I'm talking about, speed is always relative, whether it's relative to Earth, the Sun, the Center of the Galaxy, or yourself. The speed of an object when one is observing its qualities must be measured in relation to the observer. And when the wavelength of an object is dependant on the speed of the object, it is also dependent on the relative position, or speed of the observer.

Originally posted by Belisarius


*The speed of an object when one is observing its qualities must be measured in relation to the observer. * .

Speed of an object when viewed from that perspective. The same object ,same speed,
could be perceived to be at a different speed from a different perspective without a change
in our objects constant speed.

Originally posted by Belisarius


That's what I'm talking about, speed is always relative.

Speed seems to be the constant and perception relative.


Now you've got me looking for my Einstein.

The speed of light is constant regardless of the frame of reference.

Originally posted by bradybaker
The speed of light is constant regardless of the frame of reference.

Why is that? I would think that if you were travelling away from an object (at the speed of light) that was travelling at the speed of light, then the object would be perceived to be moving twice the speed of light.

the actual speed of light does change when passing from one medium to another
it's called refraction
However, when most people say "Speed of Light"
they usually mean the actual speed of light through a vacuum
this is constant (excluding gravitational forces)

Originally posted by InTheMoment

Why is that? I would think that if you were travelling away from an object (at the speed of light) that was travelling at the speed of light, then the object would be perceived to be moving twice the speed of light.

if you are travelling away from an object at the speed of light
the light reflected off of that object would never reach you
you would not be able to see that object

OK, here we go.

The speed of light is constant, regardless of one's frame of reference, or perspective. The typical thought experiment used to illustrate this concept is as follows:

Imagine you are traveling past Earth in a spaceship at the speed of light. Now turn on your headlights. What happens? Typically, assuming the speed of light is constant, one also assumes that the light stays put, right there at the source of illumination. To an observer on Earth, this is true. However, to you (in the spaceship), the light travels away from you at, you guessed it, the speed of light. This leads to the unfortunate conclusion that the two observers are seing two completely different things. In fact, they do not. At that speed, time works differently. It's illogical, but apparently proven by some top notch smart-asses. Like Einstien and Hawking and the like. Of course, a ship could not travel that fast, so the experiment remains imaginary, but the principle holds.

All other speeds are relative. Yes they are, Carter. If only one thing existed in the universe, and it was going realy realy realy fast, how could you tell? Assuming you are also there, then it is by how fast it passes you. How do you know you're not the one moving? The human stomach can detect acceleration, but not velocity. That's relative.

As far as refraction slowing down light, it doesn't really. It's an illusion. What happens, is light slams into a molecule. Different mollecules have different Indices of Refraction. The struck molecule absorbs the light and converts it into electromagnetic potential, then holds on to it. A higher Index of Refraction means that it can hold on to more EM before it "pops", spitting the light back out another side, based on it's frequency. The time this takes is longer that it would take the light to fly past the molecule unhindered, ergo the illusion of being slowed. The speed of light is unaffected.

I don't think I touched the original question, but that's what I know of such things.

http://physicsweb.org/articles/news/7/7/9

I almost mentioned those experiments. The "faster" and "slower" light speeds are just what I described above: variances in the mediums' Index of Refraction, in this case accomplished though the clever use of lasers, and if I'm not mistaken, in the case of the "stationary" light, an exotic Praseodymeum (sp?) crystal. We have accomplished what was once considered an impossibility - negative refraction - through the development of metamaterials. The light comes out of the other side of the molecule faster than it could have traveled past it unhindered. Still an illusion. All it proves is that information can travel faster than the speed of light. But that's another can of worms entirely, now isn't it?

hey Adam,

Originally posted by bradybaker
The speed of light is constant regardless of the frame of reference.

I'm not talking about light waves, I'm talking about matter waves. Matter doesn't travel at the speed of light, it travels at a speed relative to the observer. I'm not sure who the physicist who came up with the concept of matter waves, something like Delabergie.

More like Debroglie (that isnt spelt right)

Originally posted by O-Nieronaut
OK, here we go.

The speed of light is constant, regardless of one's frame of reference, or perspective. The typical thought experiment used to illustrate this concept is as follows:

Imagine you are traveling past Earth in a spaceship at the speed of light. Now turn on your headlights. What happens? Typically, assuming the speed of light is constant, one also assumes that the light stays put, right there at the source of illumination. To an observer on Earth, this is true. However, to you (in the spaceship), the light travels away from you at, you guessed it, the speed of light. This leads to the unfortunate conclusion that the two observers are seing two completely different things. In fact, they do not. At that speed, time works differently. It's illogical, but apparently proven by some top notch smart-asses. Like Einstien and Hawking and the like. Of course, a ship could not travel that fast, so the experiment remains imaginary, but the principle holds.

All other speeds are relative. Yes they are, Carter. If only one thing existed in the universe, and it was going realy realy realy fast, how could you tell? Assuming you are also there, then it is by how fast it passes you. How do you know you're not the one moving? The human stomach can detect acceleration, but not velocity. That's relative.

As far as refraction slowing down light, it doesn't really. It's an illusion. What happens, is light slams into a molecule. Different mollecules have different Indices of Refraction. The struck molecule absorbs the light and converts it into electromagnetic potential, then holds on to it. A higher Index of Refraction means that it can hold on to more EM before it \"pops\", spitting the light back out another side, based on it's frequency. The time this takes is longer that it would take the light to fly past the molecule unhindered, ergo the illusion of being slowed. The speed of light is unaffected.

I don't think I touched the original question, but that's what I know of such things.

Thankyou for expaining refraction in some detail. Always wonderd why that happend and neither my high-shool or college (6th-form) education ever answerd it in enought detail.

I’ve studied a bit of physics, so I thought I’d spew a bit of it out here. Richard Feynman does a really good job of explaining relative perceptions of clocks. I’d recommend taking a look at his book called “Six Not So Easy Pieces”.

Some of the stuff I remember the most about mass and energy is that when I was studying sub-atomic particles, the mass was measured in electron volts (a unit of energy). The smaller the particles got, the more they behaved like waves.

One interesting puzzle that I recall is: Take a bucket of water and spin it on a potters wheel or something like that. The water inside gets pushed up the side of the bucket and makes a cone like shape in the surface of the water (centrifugal). Now, take the bucket to the centre of the universe, and spin the universe around the bucket... What happens to the water?

Explain that One!