# Special Relativity Contains Massive Error

#### David

Originally posted by Tempest
Now, either the distance the atom is away from the photon in this photonic frame has been Lorentz contracted or not. Assume it has been contracted.
Psst, in a 1907 paper, Einstein admitted that the geometric shape of a body does not really “contract” due only to “relative motion”. So if we have your frame in which the two photons are emitted be about 186000 miles long, in each direction from the atom that emits the photons, the length of that frame doesn’t really “shrivel up” just because some other frame is moving relative to it.

He said it this way:

Einstein said in 1907
“The shape of a body in the sense indicated we will call its ‘geometrical shape’. The latter obviously does not depend on the state of motion of a reference frame.”
In Lorentz’s 1904 relativity theory, his “contraction” was due to a mass moving through an ether and being contracted by that motion, by means of the mass somehow “feeling” a resistance to its motion through the ether and contracting as a result, much like if we hold a balloon inside a moving car and it has a round shape, then we hold it outside the window of the car and the air resistance changes its shape. But just “relative motion” alone, between two masses, can not cause a “length contraction” in either of the masses.

#### StarThrower

Re: Re: Special Relativity Contains Massive Error

Originally posted by David
Psst, in a 1907 paper, Einstein admitted that the geometric shape of a body does not really “contract” due only to “relative motion”. So if we have your frame in which the two photons are emitted be about 186000 miles long, in each direction from the atom that emits the photons, the length of that frame doesn’t really “shrivel up” just because some other frame is moving relative to it.

He said it this way:

In Lorentz’s 1904 relativity theory, his “contraction” was due to a mass moving through an ether and being contracted by that motion, by means of the mass somehow “feeling” a resistance to its motion through the ether and contracting as a result, much like if we hold a balloon inside a moving car and it has a round shape, then we hold it outside the window of the car and the air resistance changes its shape. But just “relative motion” alone, between two masses, can not cause a “length contraction” in either of the masses.
David, it seems you have misunderstood the mathematics of relativity. There is something called the Lorentz transformations, and these transformations have to do with how the coordinates of one system transform into another system in relative motion to it.

Now, as a result of these transformations, a ruler which runs from zero to one meter in one coordinate system, will NOT have that length in a coordinate system in relative motion, so you are misunderstanding an implication of the theory of relativity. You are misunderstanding it, because you don't understand what the Lorentz transformations say. One of the consequences of the Lorentz transformations is that the length of the ruler is a function of the relative speed v, and the speed of light c. This means that a ruler which is one mile long in a frame at rest with respect to the ruler, will be shorter in a frame in which that ruler is moving. The length the ruler will be in a frame in which it is moving is given by:

$$L = L_0 \sqrt{1-v^2/c^2}$$

So as you can see, if the ruler is accelerating in some inertial frame, the closer its speed gets to c, the shorter it gets, and when its speed actually reaches c, then its length in that frame is equal to zero, contrary to the fact that it is a ruler, and by definition a ruler is a one dimensional entity. Hence, no ruler can be accelerated to the speed of light in an inertial frame.

Go study the Lorentz transformations. I can give you a link to a site if you need one. I would also suggest trying to derive the contraction formula, and the time dilation formula from the transformations. It's a good mathematical excercise. Respond to me if you have any questions about this.

#### StarThrower

Tempest,

This post has really got me thinking. Things are very clear from the atomic frame. Two photons are simultaneously emitted from an atom which is at rest in an inertial reference system, after one second, they are both 299792458 meters away from the center of mass of the atom, by one of the postulates of relativity.

Then you do something interesting, you switch to a reference frame traveling with one of the photons, so that in that frame, the photon is at rest (lets say at the origin). But clearly, by the relativity postulate, a photon cannot be at rest in an inertial reference frame, since its speed must be equal to c in an inertial reference frame. So if the theory of relativity doesn't contradict, the only possible conclusion is that this frame isn't an inertial reference frame.

That being said, if you can now show that the frame in question MUST be an inertial reference frame, you would likely be onto something. And so this is why you have gotten me thinking. Here is what would have to be done. You would have to prove that if X is an inertial reference frame, and Y is a reference frame whose origin is moving at a constant speed relative to the origin of X, and whose axes aren't rotating in frame X, then Y is an inertial reference frame.

Then, because the photon is moving at a constant speed in the atomic frame, it would follow by a theorem not yet proven, that a frame in which the photon is at rest, is an inertial reference frame. And since one of the consequences of the special theory is that in any inertial reference frame the speed of any photon is c, you would have accomplished something.

So this brings the attention to inertial reference frames. If we simply define an inertial reference frame as a reference frame which isn't accelerating relative to any other inertial reference frame, your proof would be complete, but your definition would be circular.

So then you need a definition which avoids circularity.

Now, a well known consequence of the special theory, is that mass (like length and time) is relative. The formula used by Einstein was:

$$M = \frac{m}{\sqrt{1-v^2/c^2}}$$

So since we are still operating under the assumption that the relativity postulate is true, we have access to the above equation, and I was thinking of trying to use it in a definition of an inertial reference frame, other than a reference frame which isn't accelerating. Let me know your thoughts

Also I am wondering if you can use the fact that in the 'photonic' frame the photon's rest mass is equal to zero.

I was sort of thinking like this

Suppose that a body of mass M is at rest in the atomic system. It would then follow that its mass M is equal to its rest mass m, since v=0. And similarly for all other bodies at rest in the atomic frame. And for any body which is moving in the atomic frame, the mass of that object isn't equal to its rest mass, but rather is something greater, given by the formula above. Now, for photons in the atomic frame, we have division by zero error from that formula, unless the rest mass of a photon is zero. So a consequence of the theory of relativity, is that in any reference frame in which a photon is at rest, that photon MUST have a mass of zero. And we already know that relativity implies that there are no inertial reference frames in which a photon is at rest, though in your 'photonic' frame the photon is clearly 'at rest', from which we must conclude that the photonic frame is non-inertial. But here is what gets me.

Because there were two photons emitted from the atom, the atom wasn't subjected to a net force. Now from in the photonic system, the atom is following Newton's law of inertia, from which it does follow that the photonic system is an inertial system. You are onto something.

In other words, the atom never accelerated relative to the photon, and it was subject to no net force, and so the proper inference from the photonic system, is that the photonic system is an inertial reference frame.

Thank you

P.S. I just started wondering if a clear contradiction to quantum physics is visible. We know that in the atomic frame, the energy of the photon is given by E = hf, so I am wondering if this can be used. It would at least show the two theories are incompatible. IN that photonic frame the rest mass of the photon is zero.

$$Mc^2 = hf = hc/\lambda$$

From which it follows that

$$Mc = h/\lambda$$

Since c is greater than zero, we can divide boths sides by c to obtain

$$M \lambda = h/c$$

And so we have:

$$\frac{m \lambda}{\sqrt{1-v^2/c^2}} = h/c$$

And I think the wavelength is relative too. Hence there is a relationship:

$$\lambda = \lambda_0 \sqrt{1-v^2/c^2}$$

Hence we have:

$$m \lambda_0 = h/c$$

and since m =0 we arrive at:

$$0 = h/c$$

Which is a clear contradiction. This at least shows quantum physics and relativity to be at odds. Let me know what you think.

Last edited:

#### David

Re: Re: Re: Special Relativity Contains Massive Error

Originally posted by StarThrower
David, it seems you have misunderstood the mathematics of relativity. There is something called the Lorentz transformations, and these transformations have to do with how the coordinates of one system transform into another system in relative motion to it.

Now, as a result of these transformations, a ruler which runs from zero to one meter in one coordinate system, will NOT have that length in a coordinate system in relative motion, so you are misunderstanding an implication of the theory of relativity. You are misunderstanding it, because you don't understand what the Lorentz transformations say. One of the consequences of the Lorentz transformations is that the length of the ruler is a function of the relative speed v, and the speed of light c. This means that a ruler which is one mile long in a frame at rest with respect to the ruler, will be shorter in a frame in which that ruler is moving. The length the ruler will be in a frame in which it is moving is given by:

$$L = L_0 \sqrt{1-v^2/c^2}$$

I have copies of Lorentz’s 1895 and 1904 relativity papers. He introduced his Lorentz Transformation in 1895 as a way to try to explain the results of the Michelson Morley experiment.

He specifically said in his 1895 paper:

Lorentz said in 1895:

”Thus one would have to imagine that the motion of a solid body (such as a brass rod or the stone disc employed in the later experiments) though the resting ether exerts upon the dimensions of that body an influence which varies according to the orientation of the body with respect to the direction of motion.”
Just “relative motion” can not “exert an influence” on a body in any manner.

Sorry, but rulers don’t “contract” just due to “relative motion”, and Einstein agreed in 1907.

A ruler in “relative motion” to some distant ruler, doesn’t know it’s “moving”, and thus feels no force compelling it to shrink. You need to study more about the various relativity theories.

Originally posted by StarThrower
So as you can see, if the ruler is accelerating in some inertial frame, the closer its speed gets to c...
You can’t jump from a “relatively moving” ruler to an “accelerating ruler” just like that. Those are two different things.

And there is no such thing as something “accelerating in some inertial frame”.

#### David

Originally posted by StarThrower
But clearly, by the relativity postulate, a photon cannot be at rest in an inertial reference frame, since its speed must be equal to c in an inertial reference frame.
I've generally found that nature doesn't always obey the ancient postulates of mortal men.

Actually, many astronomers today say that distant 1-c galaxies are moving away from the earth at the relative speed of 1-c, and, therefore, when they emit a photon aimed in our direction, that photon is moving at “0” velocity in our direction. The photon later speeds up relative to us. See the Davis-Lineweaver paper to learn about this new theory.

It’s time to move on in physics and astronomy and move into the 21st Century.

#### wisp

Tempest

You can let your atom's frame be absolute relative to the ether. Then galilean transformations hold, and time dilation effects in that frame are zero.

When you put yourself in a moving frame F3 (moving at 1 m/s) then you must take into account a small time dilation effect, but it can be ignored and the galilean transformation still holds (on the assumption sr is wrong).

In the photon frame the effect of time dilation is infinite and so an observer cannot make any measurements.

Wisp theory http://www.kevin.harkess.btinternet.co.uk has transformations (sections 7.11 and 7.11.1) that might help you out. It looks at this from both absolute and relative frames of reference. The theory does not use the Lorentz - FitzGerald contraction; it treats events as having absolute simultaneity, and treats distances as invariant.

The theory does not support sr's claim that the speed of light is constant, although it does show that much of the predictions of sr are correct.

Your idea's will lead you to thinking that the speed of light cannot be constant and you will find it near impossible to convince anyone that this is so.

Last edited by a moderator:

#### deda

Re: Re: Re: Re: Special Relativity Contains Massive Error

Originally posted by chroot

In other words, when you're going c, everything in the universe is zero distance from you.

- Warren
It quite amazes me.If every thing is zero distant from the photon when it travels at c then if it has to go anywhere then it's already there even without moving.
It's not all, but then photon is already every where.

Does it confirms that the light transmition is instaneous from the photon's point of view?

My purpose is a good debate. I'll jepardise my membership for it if I have to!!!

#### StarThrower

Re: Re: Re: Re: Special Relativity Contains Massive Error

Originally posted by David
I have copies of Lorentz’s 1895 and 1904 relativity papers. He introduced his Lorentz Transformation in 1895 as a way to try to explain the results of the Michelson Morley experiment.

He specifically said in his 1895 paper:

Just “relative motion” can not “exert an influence” on a body in any manner.

Sorry, but rulers don’t “contract” just due to “relative motion”, and Einstein agreed in 1907.

A ruler in “relative motion” to some distant ruler, doesn’t know it’s “moving”, and thus feels no force compelling it to shrink. You need to study more about the various relativity theories.

You can’t jump from a “relatively moving” ruler to an “accelerating ruler” just like that. Those are two different things.

And there is no such thing as something “accelerating in some inertial frame”.
David, the ether concept was discarded, and the transformations are now interpreted as transformation of coordinates from one reference frame to another. It is completely irrelevent what their formulator intended them to mean. The mathematics drive the conclusions. That math discards the notion of ether.

What Lorentz felt was responsible for the shrinking is totally irrelevent to the mathematics of relativity. The transformations are coordinate transformations. You can derive the formula for length contraction and time dilation from using a very simple argument, which will prove to you that the length of a moving ruler shrinks, because it is in motion in some inertial reference frame.

No jump is made, you perform the necessary mathematics. You differentiate velocity with respect to time.

Acceleration = dv/dt. Nothing to it.

And of course there is such a thing as accelerating in an inertial reference frame.

An inertial reference frame is a reference frame in which all three of Newton's laws are satisfied. One of those laws is Newton's third law, which states that

F12 = -F21

The symbol F is for force, and force is equal to mass times acceleration. Hence, objects in inertial reference frames can accelerate in those frames. You are making a conceptual error.

Last edited:

#### StarThrower

Originally posted by David
I've generally found that nature doesn't always obey the ancient postulates of mortal men.

Actually, many astronomers today say that distant 1-c galaxies are moving away from the earth at the relative speed of 1-c, and, therefore, when they emit a photon aimed in our direction, that photon is moving at “0” velocity in our direction. The photon later speeds up relative to us. See the Davis-Lineweaver paper to learn about this new theory.

It’s time to move on in physics and astronomy and move into the 21st Century.
David,

You left out the remainder of the quote:

"So if the theory of relativity doesn't contradict, the only possible conclusion is that this frame isn't an inertial reference frame."

The logic in that thread was flawless, there was nothing to question at all.

#### David

Re: Re: Re: Re: Re: Special Relativity Contains Massive Error

Originally posted by StarThrower
from using a very simple argument, which will prove to you that the length of a moving ruler shrinks, because it is in motion in some inertial reference frame.
Einstein basically retracted his “the moving ruler shrinks” hypothesis in 1907, when he said:

“The shape of a body in the sense indicated we will call its ‘geometrical shape’. The latter obviously does not depend on the state of motion of a reference frame.”

Just “relative motion” alone can not cause any ruler in the universe to “shrink”. Some type of “force” or changing force must be placed upon the ruler to get it to shrink. However, I know of quite a lot of people who do believe a “relatively moving” ruler “shrinks”, because they’ve heard this rumor so many times.

#### StarThrower

David,

There is nothing for Einstein to recant, because the assumption that the speed of light is c in any inertial reference frame, leads to the conclusion that the length of a ruler which is moving in someone's inertial reference frame, has a length in that frame which is less than the ruler's proper length. You really aren't understanding relativity at all. There is a simple derivation of the time dilation formula, and length contraction formula which will prove that the contraction occurs in absence of any force, and is solely due to relative motion alone. Of course these conclusions are contingent on the postulate that the speed of light is c in any inertial reference frame, but they are the conclusions. Here is their derivation.

Consider an experiment designed to measure the speed of light. A photon is going to be fired from a photon gun at a mirror, it will then bounce back, and the time of travel will be measured by a single clock at rest with respect to the photon gun, and the mirror. Let the distance from the photon gun to the mirror be denoted by d, and let the time it takes for the photon to move from the gun back to the gun be denoted by $$\Delta t$$.

Now, the distance the photon travels in time delta t, is 2d. Let us denote the speed of the photon in this frame be denoted by c. Thus, in this frame the speed of light is given by:

$$c = 2d/ \Delta t$$

Now, consider things from another inertial reference frame which is moving at a constant speed v relative to the photon gun system. In this inertial frame the photon travels an isosceles triangular path. Let a clock in this frame measure the time of the event as:

$$\Delta t'$$

Now, the altitude of the triangle is d, the base of the triangle is

$$v \Delta t'$$

Now, the sides of the triangle can be found from the Pythagorean theorem. Now each side of the triangle has a length which is equal to the speed of light in this frame (which I will denote by c') times half the time of the event in this frame which is:

$$\Delta t'/2$$

Thus, the side length of the triangular path of the photon is:

$$(c' \Delta t')/2$$

And the height of this triangle is d.

And the base is given by:

$$v \Delta t')/2$$

Hence by the Pythagorean theorem the following relationship holds:

$$d^2 + [v \Delta t')/2 ]^2 = [c' \Delta t'/2]^2$$

From which it follows that:

$$(2d)^2 + [v \Delta t')]^2 = [c' \Delta t']^2$$

$$(2d)^2 = [c' \Delta t']^2 - [v \Delta t')]^2$$

$$(2d)^2 = \frac{[(c')^2 - v^2]}{(\Delta t')^2}$$

And we already know that 2d = c \Delta t

From which it follows that:

$$(c \Delta t)^2 = \frac{[(c')^2 - v^2]}{(\Delta t')^2}$$

From which it follows that:

$$(c \Delta t')^2 = [(c')^2 - v^2](\Delta t)^2$$

From which it follows that:

$$(\Delta t')^2 = [(c'/c)^2 - v^2/c^2](\Delta t)^2$$

Now, the previous formula is true, regardless of whether or not the special theory is true. The fundamental postulate of SR is that c=c', let us make that assumption at this point in the mathematical analysis. Hence we have:

$$(\Delta t')^2 = [1 - v^2/c^2](\Delta t)^2$$

Now, take the square root of both sides of the above equation:

$$\Delta t' = \sqrt{[1 - v^2/c^2]}\Delta t$$

And so finally we get the time dilation formula:

$$\frac{\Delta t'}{\sqrt{[1 - v^2/c^2]}} = \Delta t$$

Half of the work is done. The other half of the work consists of deriving the formula for Length contraction, from the above formula for time dilation. I will let you do the work. The point is, there will be length contraction of rulers, and of distances traveled. There are multiple ways to draw the conclusion, and the only assumption that was made, was that c=c', which is the Postulate of relativity. Thus, length contraction is a consequence of the postulate of relativity, and has absolutely nothing whatsoever to do with applied forces. It is a relativistic effect, that only has to do with relative motion, as a derivation of the formulas fully reveals.
A classical approach would have said that not (c=c'), but the times of the event in the frames was equal.

Last edited:

#### Mumeishi

I'm not a physicist but I think this quotation from Einstein has some bearing on the flawed premise of this thread:

How, then, could such a universal principle be found?
After ten years of reflection such a principle resulted
of sixteen: If I pursue a beam of light with the
velocity c (velocity of light in a vacuum), I should
observe such a beam of light as a spatially oscillatory
electromagnetic field at rest. However, there seems to
be no such thing, whether on the basis of experience or
according to Maxwell's equations. From the very
beginning it appeared to me intuitively clear that,
judged from the standpoint of such an observer,
everything would have to happen according to the same
laws as for an observer who, relative to the earth, was
at rest. For how, otherwise, should the first observer
know, i.e., be able to determine, that he is in a state
of fast uniform motion?
-- Albert Einstein, "Autobiographical Notes" in "Albert
Einstein: Philosopher-Scientist," Ed. Paul Arthur
Schilpp

#### David

Originally posted by StarThrower
David,

There is nothing for Einstein to recant, because the assumption that the speed of light is c in any inertial reference frame, leads to the conclusion that the length of a ruler which is moving in someone's inertial reference frame, has a length in that frame which is less than the ruler's proper length. You really aren't understanding relativity at all. There is a simple derivation of the time dilation formula, and length contraction formula which will prove that the contraction occurs in absence of any force, and is solely due to relative motion alone.
Sorry, but you are mistaken. And, anyway, Einstein admitted in 1907 that there is no such thing as geometrical “length contraction” caused only by relatively moving frames.

#### StarThrower

Originally posted by David
Sorry, but you are mistaken. And, anyway, Einstein admitted in 1907 that there is no such thing as geometrical “length contraction” caused only by relatively moving frames.
I'm not mistaken, try going through the derivation. I will explain it, if it wasn't clear from the post.

#### David

Originally posted by StarThrower
Thus, length contraction is a consequence of the postulate of relativity, and has absolutely nothing whatsoever to do with applied forces. It is a relativistic effect, that only has to do with relative motion, as a derivation of the formulas fully reveals

Experimentation and observation suggests it is “c” inside a gravitational field when measured by an atomic clock resting on the surface of an astronomical body inside that field and when the light waves/photons are passing by that particular atomic clock. This is not quite the same as an “inertial reference frame,” because of the downward force of the gravity along the z axis. Einstein’s inertial reference frames in the SR theory only dealt with the x axis, and they had no gravitational potential anywhere along that axis.

So, we can’t think of a small-mass “inertial reference frame” free floating in space in reference to the speed of light, if that frame has no gravitational potential along any axis, because that is the incorrect way to look at the situation. The earth’s surface is an “inertial reference frame” along the x and y axes, but not along the z axis. It is the gravitational potential along the z axis that gives light its local speed of “c” at the surface of the earth.

Let me see if I can explain something that took me a long time to learn. The “relatively moving” frames of the Kinematical part of the SR theory do nothing to each other. They don’t even know the other frame exists.

However, in the Electrodynamical part of his paper he has the electrons of one frame moving around inside the fields of the other frame. I know he doesn’t mention fields, but they are there in his paper. They are what regulates his speed of light inside each frame, and that is apparently what regulates the speed of light to “c” at the surface of the earth.

So it is the Kinematical part of the paper that is incorrect, not the Electrodynamical part. As he gradually developed his GR theory, he became more involved with understanding how gravitational fields influence both stationary and moving atoms.

The “length contraction” of the Kinematical part of SR theory is due to the c – v and c + v phenomena of one observer looking into a relatively moving frame and looking into the light speed regulator of the other frame. In his theory, he has two separate light-speed regulators. Each one travels as being fixed with each frame, one per frame. So, while the frames move relative to each other, so do the light speed regulators. Just like two planets passing each other. Just like the sun has its own light speed regulator at the sun’s surface (it’s local gravitational field), and just like the earth has its local light speed regulator at the earth’s surface (the earth’s gravitational field). But just the "relative motion" of these two local bodies or fields can not cause any ruler or anything else to "length contract".

#### David

Originally posted by StarThrower
I'm not mistaken, try going through the derivation. I will explain it, if it wasn't clear from the post.

I’ve got his equations right here: Notice the c – v and the c + v?

That’s how he gets his time dilation and his length contraction. It’s a hypothetical mathematical manipulation, caused by a light beam synchronization signal going from A to B at c and B to A at c, in the “stationary” frame, but going from A to B at c – v and B to A at c + v in the “moving” frame.

But this has nothing to do with the real geometrical length of the moving rod or ruler. In 1907 he admitted this and change the “length contraction” from a “geometrical” contraction to a “kinematical” contraction, meaning it’s only an illusion caused by his thought experiments and his math. It doesn’t exist in real life, not due to just “relative motion” alone.

#### David

StarThrower,

He says in the 1907 paper:

“It is clear that observers who are at rest relative to a reference system S can ascertain only the kinematical shape with respect to S of a body that is in motion relative to S, but not its geometrical shape.”

See?

The "length contraction" is a visual hypothetical thing that only exists inside the 1905 paper. It's not a real thing in nature or physics.

#### David

StarThrower,

Einstein further said in 1907:

“In the following, we will usually not distinguish between explicitly between the geometrical and kinematical shape; a statement of geometric nature refers to the kinematic or geometric shape, respectively, depending on whether the latter refers to a reference system S or not.”

Ok, so S is his “stationary” system. IE, that is basically the “earth” with the earth’s z-axis gravity not being considered, not in 1905 and not in 1907. The S’ system is “someplace else” that is moving with respect to S.

So, when he refers to an x dimension in S, he is referring to a real “geometrical” dimension, but when he is referring to an x’ dimension in S’ (the moving system), he is referring to a “kinematic” dimension. In other words, he is referring to a visual illusion.

This revelation might come as a shock and a disappointment to some people, but I’ve got his 1907 paper right here in front of me.

Seems that quite a lot of physics professors still think he was talking about a real “geometrical” length contraction in his 1905 paper, and so do many science writers and TV documentary makers today.

Seems that there is no real geometrical “length contraction” due just to “relative motion” after all. Such a common belief has been a big mistake for the past 98 years.

Likewise, there is no such thing as real “time dilation” due only to “relative motion”.

#### StarThrower

David,

The entire analysis which I gave, can be performed in deep space, where there is no gravitational field, and the result will be obtained. The derivation there, makes only one assumption, that c=c', and it is the clearest derivation of the time dilation formula, and length contraction formula which I have ever come across.
What Einstein thought is now irrelevent. You were given a mathematical derivation of the two formulas, and it is clear that if the speed of light is the same in any inertial frame, then the length of a ruler contracts in a frame in which it is moving, solely based upon the fact that there is relative motion.
You have a clear derivation there, it is totally independent of the thoughts of Einstein. Now, if you have a problem with the length of a body contracting, solely due to relative motion, then don't cancel c with c`, and become a non-relativist. Again, I really don't know what to tell you, other than the thoughts of Einstein are now irrelevent, and there is a mathematical derivation of the formulas which proves my point conclusively.

Last edited:

#### David

StarThrower,

Ok, well, we aren’t getting anywhere, so let me change the subject.

Let me ask you this question. In this demonstration, why wouldn’t the dot of laser light hit the card the slits are on, right in the middle between the slits, and thus not go through either slit?

Last edited by a moderator:

#### StarThrower

Originally posted by David
StarThrower,

Ok, well, we aren’t getting anywhere, so let me change the subject.

Let me ask you this question. In this demonstration, why wouldn’t the dot of laser light hit the card the slits are on, right in the middle between the slits, and thus not go through either slit?

It's been a long time since I've done the double slit experiment using a laser on a diffraction grating. As I recall, the distance between the two slits has to be on the order of the wavelength of the light, in order to get a diffraction pattern. Hence, if the distance between the slits is large, the laser beam will hit the center, and the photons will not pass through. There are plenty of good derivations of the formula for interference pattern on the web. The formula predicts where the light and dark fringes are, with the most intense maximum being located at the midpoint, between the slits but on the far wall.

$$n \lambda = d sin(\theta)= d (X/L)$$

d = distance between slits
x = distance between bright fringes
L = distance from slits to far screen
lambda = wavelength

In the formula above, sin theta is approximately equal to tan theta for small angles, and hence we can write X/L = sin theta.

So the textbook answer to your question, is that the distance d has to be on the order of the wavelength of the laser light, and the diffraction pattern appears, if there is a solid wall there, no photons will strike the far screen, and if there is no wall there, the beam will hit the far wall at a dot.
So then the only thing left to do, is explain why an interference pattern ever appears, and why it appears even if only one photon strikes the two slits.

I will say that a single solid particle cannot create a diffraction pattern, and that what is going on at the level where the diffraction pattern occurs is not understood by anyone yet, and that this is due to a faulty model.

Last edited by a moderator:

#### David

Originally posted by StarThrower
on at the level where the diffraction pattern occurs is not understood by anyone yet, and that this is due to a faulty model.
Thanks!

#### russ_watters

Mentor
Re: If that's not massive error then I'm Tom Johns

Originally posted by deda
Einstein versus Him SelfThis proves that SR kind of calculus is not manageable.
All it proves is that a photon's point of view isn't a valid reference frame for SR. Not news and not a problem for SR.