On Friday, June 3, 2022 at 2:09:00 PM UTC-5, RichD wrote:
> On June 3, wrote:
> > Police Lidar guns have a "gun sight" that you look through to make sure
> > you are pointing at the right target. When you pull the trigger, it does a
> > distance measurement to the target, then about 1/10th of a second later
> > it does another measurement.
> > Knowing the speed of light, the gun then calculates the target's speed by
> > dividing the difference in distance by the time between measurements.
> Big hole in your analysis, Ed -
>
> The speed of light emitted by the gun is known. But the light speed
> reflected from the target is c + v, remember?

NONSENSE! The speed of light is c, and can NEVER be c+v. You only
get c+v when you have light traveling at c and hitting an object that is
moving toward the light at v. When that happens, the photon's wave
frequency seems SHORTER to the receiving atom that absorbs the
photon. Energy is thereby added to the NEW photon that is emitted
by that atom back to the radar gun.

>
> And v is UNKNOWN, that's the point! Hence the gun cannot calculate
> the target's speed.

The gun CALCULATES v by comparing the oscillation rates of the photons
it emitted to the oscillation rates of the photons it received back from the
target. A calculator for that is at this link: http://hyperphysics.phy-astr.gsu.edu/hbase/Sound/radar.html#c4

>
> I'm surprised that an uberlogician like yourself would err this way -

You're just misunderstanding something.

Ed

On Friday, June 3, 2022 at 2:32:39 PM UTC-5, RichD wrote:
> On June 2, wrote:
> > > >>> I was just trying to debunk the idea that all motion is relative, and if
> > > >>> A is moving at 100 kps relative to B, then B is also moving at 100 kps
> > > >>> relative to A. That is nonsense. We know who is moving faster because
> > > >>> one of them had to ACCELERATE to get to the higher speed.
> >
> >> >> A Camaro travels east on Route 80, at 90 mph, approaching exit 60.
> >> >> A police radar trap sits at that point.
> >> >> The car is actually moving, because he had to accelerate. The police car
> >> >> is obviously stationary.
> >> >> Now the trick: the police car is atop a very long flatbed train, zooming
> >> >> eastbound at 90 mph. It's driving westward (opposite) the train,
> >> >> 90 mph. Hence the cop is STATIONARY, relative to exit 60.
> >> >> Now look at the police car vs. Camaro. If relative motion is bunk, which
> >> >> is REALLY moving, and which is stationary?
> >
> >>> If I understand you correctly, the police car is technically "stationary" since
> >>> it is not moving relative to the earth, and the Camaro is moving at 90 mph.
> >
> >> Correct.
> >> To precise, police car's speed is irrelevant, only the speed
> >> of the radar gun matters.
> >
> >>> A radar gun in the police car would definitely measure the speed of the
> >>> Camaro to be 90 mph.
> >
> >> i) Camaro zooms east at 90 mph. Cop is parked, obviously stationary.
> >> ii) Camaro, same as case (i). But the cop is driving westward at 90 mph.
> >
> > No, the cop is racing to remain "stationary." His radar gun doesn't "know"
> > about the train or how the cop car is moving aboard the train. All the gun
> > "knows" is that it is "stationary" relative to the ground.
> >
> >> In (ii), they are moving the same speed THROUGH SPACE,
> >> in opposite directions. In fact, we can ignore the earth completely!
> >> What's pertinent is their speed through space. They accelerated
> >> identically, to the same speed. Therefore their closing speed must be 180.
> >
> > The closing speed for the train and the Camaro is 180,
>
> No, train and Camaro move in sync, eastbound, no relative motion.

No. The train was moving WEST at 90 mph. The Camaro was moving EAST at 90 mph.
ON BOARD THE TRAIN, a cop car was moving EAST at 90 mph, which results in
no motion between the COP CAR and the GROUND. The Camaro, however, is
moving at 90 mph relative to the "stationary" cop car.

>
> > but the cop car is moving at 90 mph aboard the train, so the closing speed between the
> > cop car and the Camaro is 90 mph.
> > The gun emits photons that represent the LOCATION of the gun RELATIVE
> > TO THE GROUND. If the gun was moving, then the photons would oscillate
> > at a higher frequency that represents the guns' motion relative to the ground.
> > In your thought experiment, the cop car is STATIONARY relative to the
> > ground. That is all the gun knows.
> > And because it is STATIONARY relative to the ground, the gun emits
> > photons that oscillate at a frequency that matches the frequency that
> > would be emitted by a gun actually ON the ground.
> You're fixated on the ground.
>
> Let's remove the earth. Camaro, train, and cop car are all rocketing
> through empty space, same speeds as above. Now, what's stationary
> relative to what? Does the radar gun suffer a nervous breakdown, when
> it loses contact with earth?

Now you don't have any reference point like the earth. In the original thought
experiment, all speeds were relative to the earth. In your new version you
have no reference point. So, you have the train and the Camaro approaching
each other at a COMBINED speed of 180 mph, and you have the cop car
approaching the Camaro at 90 mph. OR you have the Camaro approaching
the cop car at 90 mph. With no earth as the reference point, the speeds
become valid both ways.

Ed

On Friday, June 3, 2022 at 3:01:27 PM UTC-5, Paparios wrote:
> El viernes, 3 de junio de 2022 a las 12:59:22 UTC-4, escribió:
> > On Friday, June 3, 2022 at 10:52:05 AM UTC-5, tjrob137 wrote:
> > > On 6/3/22 9:49 AM, Ed Lake wrote:
>
> > > The operator of the radar gun must ensure that the reflected waves come
> > > from the target vehicle, and not extraneous reflectors. The gun displays
> > > the speed corresponding to the largest Doppler shift within its beam,
> > > which combined with the operator's aiming of the beam automatically does
> > > the separation you claim cannot be done.
>
> > Right. It cannot be done because the "beam" width is 12 degrees. That means
> > that at 500 feet, the "beam" will be 105 feet wide. At 200 feet it will be 42 feet
> > wide. If the gun is pointed at an oncoming truck, the front of the truck will be
> > about 10 feet in front of the trailer. Both will reflect "waves." And there is no way
> > to separate waves from the tractor and waves from the trailer. If you can't
> > tell one wave from another, you cannot use waves to measure speeds.
> The radar detector receives all of those reflected signals and they vary in strength. Therefore, the radar detector will receive some small signals at low frequency (from static objects like poles or houses) and strong signals at the frequency of the moving vehicle. No radar looks to separate waves from the tractor from waves from the trailer (that is pure nonsense).

If you are measuring speeds by how fast waves return, waves will return FASTER
from the front of a truck than from the trailer 10 or 15 feet behind the front.
That says that radar guns DO NOT MEASURE WAVES that way. They measure
the oscillation frequencies of photons, which will be the same from all parts of
a truck that is approaching at 70 mph.

> > > > How can that be done with waves?
> > > In the obvious way: the wave emitted by the gun has a rather narrow
> > > divergence, so you can point it accurately at a target.
>
> > A BEAM has a divergence. A BEAM of photons has a divergence.
> > What is a "beam of waves"? How can it have a divergence if the
> > primary property of a wave is to spread out IN ALL DIRECTIONS from the
> > source? Can you have sound waves that are confined into a narrow beam?
> > NO! So, how are light waves different from sound waves?
> There are in every radar gun things called antennas. The radar gun transmitter/receiver antenna has a narrow directivity (of 12 degrees intead of 360 degrees).

Actually, the antenna and the cone that narrows the outgoing beam of photons
are two different things.

> > > > The operator's manual for my TS-3 radar gun says that the "beam width" is 12 degrees.
> > > > How can you have a beam width of 12 degrees if a gun emits waves?
> > > By limiting the beam divergence. It is straightforward microwave
> > > engineering to design a radar antenna that emits a beam with such a
> > > narrow divergence. Such design tools model the radar beam as a wave, not
> > > photons. You merely display your personal ignorance.
>
> > No, you display your ignorance in not knowing the difference between a BEAM
> > and a WAVE. You can easily focus PHOTONS into a beam. You cannot focus
> > sound waves into a beam. So, how do you focus light waves into a beam?
> >
> Nonsense. Read, for instance, https://en.wikipedia.org/wiki/Sonic_weapon

Why not just discuss a loudspeaker? The gun who talks into the loudspeaker
can hear the amplified sound coming out, and so can everyone in the area.
All the loudspeaker did was protect the user by directing the loudest sound
away from his ears.

Suppose you have a guy with a shrouded flashlight at one point on a square shining the
light at the opposite point on the square. People at the other two points on the
square would not be able to see ANY light from the flashlight.

Now suppose you have a guy with a loudspeaker at one point of a square yelling
at someone at the opposite corner of the square. EVERYONE would be able to
hear what is being said. The guy at the opposite corner might hear things a bit
louder, but not very much louder.

Sound waves work very different from beams of photons.

Ed

El viernes, 3 de junio de 2022 a las 16:47:19 UTC-4, det...@outlook.com escribió:
> On Friday, June 3, 2022 at 3:01:27 PM UTC-5, Paparios wrote:
> > The radar detector receives all of those reflected signals and they vary in strength. Therefore, the radar detector will receive some small signals at low frequency (from static objects like poles or houses) and strong signals at the frequency of the moving vehicle. No radar looks to separate waves from the tractor from waves from the trailer (that is pure nonsense).

> If you are measuring speeds by how fast waves return, waves will return FASTER
> from the front of a truck than from the trailer 10 or 15 feet behind the front.
> That says that radar guns DO NOT MEASURE WAVES that way. They measure
> the oscillation frequencies of photons, which will be the same from all parts of
> a truck that is approaching at 70 mph.

Nonsense. Radar guns measure the frequency difference between the transmitted frequency and the received frequency, according to the formula:

v = (c/2)Δf/fc

where c is the speed of light, fc is the emitted frequency of the radio waves, and Δf is the difference in frequency between the radio waves that are emitted and those received back by the gun.

From https://en.wikipedia.org/wiki/Radar_speed_gun

"Radar speed guns, like other types of radar, consist of a radio transmitter and receiver. They send out a radio signal in a narrow beam, then receive the same signal back after it bounces off the target object. Due to a phenomenon called the Doppler effect, if the object is moving toward or away from the gun, the frequency of the reflected radio waves when they come back is different from the transmitted waves. When the object is approaching the radar, the frequency of the return waves is higher than the transmitted waves; when the object is moving away, the frequency is lower. From that difference, the radar speed gun can calculate the speed of the object from which the waves have been bounced".

> > > NO! So, how are light waves different from sound waves?

> > There are in every radar gun things called antennas. The radar gun transmitter/receiver antenna has a narrow directivity (of 12 degrees intead of 360 degrees).

> Actually, the antenna and the cone that narrows the outgoing beam of photons
> are two different things.

Nonsense, learn how a RF antenna works (read https://en.wikipedia.org/wiki/Radiation_pattern). See the figures in the section "Typical Patterns"

> > > > By limiting the beam divergence. It is straightforward microwave
> > > > engineering to design a radar antenna that emits a beam with such a
> > > > narrow divergence. Such design tools model the radar beam as a wave, not
> > > > photons. You merely display your personal ignorance.
> >
> > > No, you display your ignorance in not knowing the difference between a BEAM
> > > and a WAVE. You can easily focus PHOTONS into a beam. You cannot focus
> > > sound waves into a beam. So, how do you focus light waves into a beam?
> > >

Sure you can. Just see the diagram of a car lights (in https://en.wikipedia..org/wiki/Headlamp). See the figure at the section Reflector Lamps.

Every light wave can be focussed into a beam (see https://en.wikipedia.org/wiki/Optical_fiber for an extrem example).

> > Nonsense. Read, for instance, https://en.wikipedia.org/wiki/Sonic_weapon

> Why not just discuss a loudspeaker? The gun who talks into the loudspeaker
> can hear the amplified sound coming out, and so can everyone in the area.
> All the loudspeaker did was protect the user by directing the loudest sound
> away from his ears.
>

A loudspeaker is built on purpose to cover a large area of a room. Of course you have several types of speakers. The woofer at around 20 Hz has a very wide sound covering. The mid range speakers have narrover coverings at 1 kHz. The twitters have a more directive pattern at 10 kHz.

> Suppose you have a guy with a shrouded flashlight at one point on a square shining the
> light at the opposite point on the square. People at the other two points on the
> square would not be able to see ANY light from the flashlight.
>

Depends on the type of flashlight. For instance a laser light will have a very narrow beam (which is invisible) and you only see the red point on the target (as everyone in the room would also see). You have a very narrow knowledge on these subjects.

On Friday, June 3, 2022 at 12:39:34 PM UTC-7, det...@outlook.com wrote:
> > > > > > A simple radar speed gun always just shows the rate of change of the distance between gun and target. A "moving radar" device determines the speed of the gun relative to the ground by measuring the rate of change of the distance between the gun and some object(s) at rest on the ground. There is nothing magical or mysterious about this.
> > > > >
> > > > > You are talking about LIDAR guns, not radar guns.
> > > >
> > > > Nope, I'm talking about radar speed guns (although the same statement applies to LIDAR speed guns). Again, a simple speed gun reads the rate of change of the distance between gun and target. If you think this is not true, go ahead and describe a situation in which you believe a simple radar speed gun reads something other than the rate of change of the distance between gun and target.
> > >
> > > Radar guns...
> >
> > I guess you missed my question, so I ask again: Please describe the circumstances in which you believe that the reading on a simple radar speed gun does *not* equal the rate of change of the distance between gun and target.
>
> Your question makes no sense.

It does make sense, because you've given some examples of what a simple radar gun reads in certain circumstances, and in each of your examples the value you say is shown by the gun equals the rate of change of the distance between the gun and the target... and yet you deny that this is what the value shown on a simple radar gun always equals. So, I'm asking you to tell me at least one circumstance in which the value that shows on a simple radar speed gun is *not* equal to the rate of change of the distance between gun and target. Do you know of any such circumstance?

On Friday, 3 June 2022 at 23:27:31 UTC+2, Paparios wrote:

> Nonsense. Radar guns measure the frequency difference between the transmitted frequency and the received frequency, according to the formula:

Radar guns measure the speed, poor halfbrain.
They USE what you say to determine it.
There is a variety of situations where they do it
correctly and a variety of situations where they don't.

On Friday, June 3, 2022 at 4:27:31 PM UTC-5, Paparios wrote:
> El viernes, 3 de junio de 2022 a las 16:47:19 UTC-4, escribió:
> > On Friday, June 3, 2022 at 3:01:27 PM UTC-5, Paparios wrote:
>
> > > The radar detector receives all of those reflected signals and they vary in strength. Therefore, the radar detector will receive some small signals at low frequency (from static objects like poles or houses) and strong signals at the frequency of the moving vehicle. No radar looks to separate waves from the tractor from waves from the trailer (that is pure nonsense).
>
>
> > If you are measuring speeds by how fast waves return, waves will return FASTER
> > from the front of a truck than from the trailer 10 or 15 feet behind the front.
> > That says that radar guns DO NOT MEASURE WAVES that way. They measure
> > the oscillation frequencies of photons, which will be the same from all parts of
> > a truck that is approaching at 70 mph.
> Nonsense. Radar guns measure the frequency difference between the transmitted frequency and the received frequency, according to the formula:
>
> v = (c/2)Δf/fc
>
> where c is the speed of light, fc is the emitted frequency of the radio waves, and Δf is the difference in frequency between the radio waves that are emitted and those received back by the gun.

I agree with everything you say, but what you consider to be a "wave" and what I
consider to be a "wave" is where we totally disagree.

You seem to believe that light travels like water waves spreading away from where
a rock is dropped in a pond.

In reality, experiments hows that light travels as individual PHOTONS, and each of
those photons has oscillating electric and magnetic fields which give the individual
photon certain "wave like" properties.

>
> From https://en.wikipedia.org/wiki/Radar_speed_gun
>
> "Radar speed guns, like other types of radar, consist of a radio transmitter and receiver. They send out a radio signal in a narrow beam, then receive the same signal back after it bounces off the target object. Due to a phenomenon called the Doppler effect, if the object is moving toward or away from the gun, the frequency of the reflected radio waves when they come back is different from the transmitted waves. When the object is approaching the radar, the frequency of the return waves is higher than the transmitted waves; when the object is moving away, the frequency is lower. From that difference, the radar speed gun can calculate the speed of the object from which the waves have been bounced".

That is a MUDDLED description. It doesn't say what a radio "signal" is. I would say
that "signal" is called a PHOTON. And when it talks about "waves," it would be correct
if those "waves" were actually oscillating electromagnetic fields in a photon.

LIGHT CONSISTS OF PHOTONS. When you do not talk about PHOTONS and instead
talk about signals and beams and waves, all you do is MISLEAD the reader and YOURSELF.

> > > > NO! So, how are light waves different from sound waves?
>
> > > There are in every radar gun things called antennas. The radar gun transmitter/receiver antenna has a narrow directivity (of 12 degrees intead of 360 degrees).
>
> > Actually, the antenna and the cone that narrows the outgoing beam of photons
> > are two different things.
> Nonsense, learn how a RF antenna works (read https://en.wikipedia.org/wiki/Radiation_pattern). See the figures in the section "Typical Patterns"

It would be more meaningful to read about DIRECTIONAL antennas: https://en.wikipedia.org/wiki/Directional_antenna

> > > > > By limiting the beam divergence. It is straightforward microwave
> > > > > engineering to design a radar antenna that emits a beam with such a
> > > > > narrow divergence. Such design tools model the radar beam as a wave, not
> > > > > photons. You merely display your personal ignorance.
> > >
> > > > No, you display your ignorance in not knowing the difference between a BEAM
> > > > and a WAVE. You can easily focus PHOTONS into a beam. You cannot focus
> > > > sound waves into a beam. So, how do you focus light waves into a beam?
> > > >
> Sure you can. Just see the diagram of a car lights (in https://en.wikipedia.org/wiki/Headlamp). See the figure at the section Reflector Lamps.
>
> Every light wave can be focussed into a beam (see https://en.wikipedia.org/wiki/Optical_fiber for an extrem example).

PHOTONS can be focused into a beam. A light "wave" is PART OF A PHOTON.
You need to DEFINE A LIGHT WAVE as YOU imagine them.

> > > Nonsense. Read, for instance, https://en.wikipedia.org/wiki/Sonic_weapon
>
> > Why not just discuss a loudspeaker? The gun who talks into the loudspeaker
> > can hear the amplified sound coming out, and so can everyone in the area.
> > All the loudspeaker did was protect the user by directing the loudest sound
> > away from his ears.
> >
> A loudspeaker is built on purpose to cover a large area of a room. Of course you have several types of speakers. The woofer at around 20 Hz has a very wide sound covering. The mid range speakers have narrover coverings at 1 kHz. The twitters have a more directive pattern at 10 kHz.

I probably should have written "megaphone" instead of "loudspeaker." A megaphone
is "a large funnel-shaped device for amplifying and directing the voice."

The point is: If you are standing behind or off to one side, you can still hear what is
said through a megaphone. You can just hear it BETTER in front of the megaphone.

> > Suppose you have a guy with a shrouded flashlight at one point on a square shining the
> > light at the opposite point on the square. People at the other two points on the
> > square would not be able to see ANY light from the flashlight.
> >
> Depends on the type of flashlight. For instance a laser light will have a very narrow beam (which is invisible) and you only see the red point on the target (as everyone in the room would also see). You have a very narrow knowledge on these subjects.

I said a "shrouded flashlight," which means a shroud prevents the light from being
seen from the side. Only someone in the BEAM can see the light.

You cannot do that with sound.

You seem unable to understand anything unless very precise wording is used,
wording that you would use.

Ed

On Friday, June 3, 2022 at 4:37:58 PM UTC-5, Al Coe wrote:
> On Friday, June 3, 2022 at 12:39:34 PM UTC-7, wrote:
> > > > > > > A simple radar speed gun always just shows the rate of change of the distance between gun and target. A "moving radar" device determines the speed of the gun relative to the ground by measuring the rate of change of the distance between the gun and some object(s) at rest on the ground. There is nothing magical or mysterious about this.
> > > > > >
> > > > > > You are talking about LIDAR guns, not radar guns.
> > > > >
> > > > > Nope, I'm talking about radar speed guns (although the same statement applies to LIDAR speed guns). Again, a simple speed gun reads the rate of change of the distance between gun and target. If you think this is not true, go ahead and describe a situation in which you believe a simple radar speed gun reads something other than the rate of change of the distance between gun and target.
> > > >
> > > > Radar guns...
> > >
> > > I guess you missed my question, so I ask again: Please describe the circumstances in which you believe that the reading on a simple radar speed gun does *not* equal the rate of change of the distance between gun and target.
> >
> > Your question makes no sense.
> It does make sense, because you've given some examples of what a simple radar gun reads in certain circumstances, and in each of your examples the value you say is shown by the gun equals the rate of change of the distance between the gun and the target... and yet you deny that this is what the value shown on a simple radar gun always equals. So, I'm asking you to tell me at least one circumstance in which the value that shows on a simple radar speed gun is *not* equal to the rate of change of the distance between gun and target. Do you know of any such circumstance?

You're just wasting your time and mine. I'm talking about how radar guns WORK,
and you are talking about how radar guns can be MISINTERPRETED to work.

Ed

On Saturday, June 4, 2022 at 7:30:18 AM UTC-7, det...@outlook.com wrote:
> > > > > > > > A simple radar speed gun always just shows the rate of change of the distance between gun and target. A "moving radar" device determines the speed of the gun relative to the ground by measuring the rate of change of the distance between the gun and some object(s) at rest on the ground. There is nothing magical or mysterious about this.
> > > > > > >
> > > > > > > You are talking about LIDAR guns, not radar guns.
> > > > > >
> > > > > > Nope, I'm talking about radar speed guns (although the same statement applies to LIDAR speed guns). Again, a simple speed gun reads the rate of change of the distance between gun and target. If you think this is not true, go ahead and describe a situation in which you believe a simple radar speed gun reads something other than the rate of change of the distance between gun and target.
> > > > >
> > > > > Radar guns...
> > > >
> > > > I guess you missed my question, so I ask again: Please describe the circumstances in which you believe that the reading on a simple radar speed gun does *not* equal the rate of change of the distance between gun and target.
> > >
> > > Your question makes no sense.
>
> > It does make sense, because you've given some examples of what a simple radar gun reads in certain circumstances, and in each of your examples the value you say is shown by the gun equals the rate of change of the distance between the gun and the target... and yet you deny that this is what the value shown on a simple radar gun always equals. So, I'm asking you to tell me at least one circumstance in which the value that shows on a simple radar speed gun is *not* equal to the rate of change of the distance between gun and target. Do you know of any such circumstance?
>
> I'm talking about how radar guns WORK, and you are talking about how radar
> guns can be MISINTERPRETED to work.

We can never agree on how a radar speed gun does what it does if we don't agree on what it does. It's well known (and anyone can verify) that the value appearing on a simple radar speed gun is always equal to the rate of change of the distance between gun and target. All the examples you gave confirm this. Note that this isn't an explanation of how the radar gun does what it does, it is simply a statement of what it does. Once we agree on what it does, we can talk about how it does it.

So, I'm asking you (for the 4th time!) for at least one example of a circumstance in which the reading on a simple radar speed gun does *not* equal the rate of change of the distance between gun and target. If you don't know of any such circumstance, then do you agree that my statement is correct, i.e., that this is what a simple radar gun does?

El sábado, 4 de junio de 2022 a las 10:26:44 UTC-4, det...@outlook.com escribió:
> On Friday, June 3, 2022 at 4:27:31 PM UTC-5, Paparios wrote:

> > Nonsense. Radar guns measure the frequency difference between the transmitted frequency and the received frequency, according to the formula:
> >
> > v = (c/2)Δf/fc
> >
> > where c is the speed of light, fc is the emitted frequency of the radio waves, and Δf is the difference in frequency between the radio waves that are emitted and those received back by the gun.

> I agree with everything you say, but what you consider to be a "wave" and what I
> consider to be a "wave" is where we totally disagree.
>

Well these few days you have been argueing against Quantum Mechanics, while at the same time you use the photon, which is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force.

From page 476 of the book Radar Technology Encyclopedia, you can read the following:

"With the advent of quantum mechanics, electromagnetic
radiant energy is seen to be created, destroyed, and transported
in discrete quanta or photons rather than through a
continuous transfer of energy implied by electromagnetic
waves in the classical representation of electrodynamics.
Because the energy transported by large numbers of photons
is, on the average, equivalent to the energy transferred in a
classical electromagnetic wave, for macroscopic applications,
including radar and communications, Maxwell’s field equations
are accurate and extremely useful tools".

> You seem to believe that light travels like water waves spreading away from where
> a rock is dropped in a pond.
>

Wrong, radar signals travel, at the speed of light, as waves which propagate in a very narrow solid angle (determined by the antenna the radar use). See the above text explaining that it is not a single photon but zillions of them traveling like a wave.

> In reality, experiments hows that light travels as individual PHOTONS, and each of
> those photons has oscillating electric and magnetic fields which give the individual
> photon certain "wave like" properties.

A single photon is a quantum object that has no a precise location. See https://en.wikipedia.org/wiki/Uncertainty_principle

"In quantum mechanics, the uncertainty principle (also known as Heisenberg's uncertainty principle) is any of a variety of mathematical inequalities asserting a fundamental limit to the accuracy with which the values for certain pairs of physical quantities of a particle, such as position, x, and momentum, p, can be predicted from initial conditions".

> >
> > From https://en.wikipedia.org/wiki/Radar_speed_gun
> >
> > "Radar speed guns, like other types of radar, consist of a radio transmitter and receiver. They send out a radio signal in a narrow beam, then receive the same signal back after it bounces off the target object. Due to a phenomenon called the Doppler effect, if the object is moving toward or away from the gun, the frequency of the reflected radio waves when they come back is different from the transmitted waves. When the object is approaching the radar, the frequency of the return waves is higher than the transmitted waves; when the object is moving away, the frequency is lower. From that difference, the radar speed gun can calculate the speed of the object from which the waves have been bounced".

> That is a MUDDLED description. It doesn't say what a radio "signal" is. I would say
> that "signal" is called a PHOTON. And when it talks about "waves," it would be correct
> if those "waves" were actually oscillating electromagnetic fields in a photon.
>

Total nonsense. A radio signal is an electromagnetic wave of a certain frequency and power.

> LIGHT CONSISTS OF PHOTONS. When you do not talk about PHOTONS and instead
> talk about signals and beams and waves, all you do is MISLEAD the reader and YOURSELF.

See above and read those references.

> > Every light wave can be focussed into a beam (see https://en.wikipedia.org/wiki/Optical_fiber for an extrem example).

> PHOTONS can be focused into a beam. A light "wave" is PART OF A PHOTON.

What?

On Saturday, June 4, 2022 at 9:53:56 AM UTC-5, Al Coe wrote:
> On Saturday, June 4, 2022 at 7:30:18 AM UTC-7, wrote:
> > > > > > > > > A simple radar speed gun always just shows the rate of change of the distance between gun and target. A "moving radar" device determines the speed of the gun relative to the ground by measuring the rate of change of the distance between the gun and some object(s) at rest on the ground. There is nothing magical or mysterious about this.
> > > > > > > >
> > > > > > > > You are talking about LIDAR guns, not radar guns.
> > > > > > >
> > > > > > > Nope, I'm talking about radar speed guns (although the same statement applies to LIDAR speed guns). Again, a simple speed gun reads the rate of change of the distance between gun and target. If you think this is not true, go ahead and describe a situation in which you believe a simple radar speed gun reads something other than the rate of change of the distance between gun and target.
> > > > > >
> > > > > > Radar guns...
> > > > >
> > > > > I guess you missed my question, so I ask again: Please describe the circumstances in which you believe that the reading on a simple radar speed gun does *not* equal the rate of change of the distance between gun and target.
> > > >
> > > > Your question makes no sense.
> >
> > > It does make sense, because you've given some examples of what a simple radar gun reads in certain circumstances, and in each of your examples the value you say is shown by the gun equals the rate of change of the distance between the gun and the target... and yet you deny that this is what the value shown on a simple radar gun always equals. So, I'm asking you to tell me at least one circumstance in which the value that shows on a simple radar speed gun is *not* equal to the rate of change of the distance between gun and target. Do you know of any such circumstance?
> >
> > I'm talking about how radar guns WORK, and you are talking about how radar
> > guns can be MISINTERPRETED to work.
> We can never agree on how a radar speed gun does what it does if we don't agree on what it does. It's well known (and anyone can verify) that the value appearing on a simple radar speed gun is always equal to the rate of change of the distance between gun and target. All the examples you gave confirm this. Note that this isn't an explanation of how the radar gun does what it does, it is simply a statement of what it does. Once we agree on what it does, we can talk about how it does it.
>
> So, I'm asking you (for the 4th time!) for at least one example of a circumstance in which the reading on a simple radar speed gun does *not* equal the rate of change of the distance between gun and target. If you don't know of any such circumstance, then do you agree that my statement is correct, i.e., that this is what a simple radar gun does?

A radar gun displays "50 mph" when the gun is stationary and it is pointed at
a target approaching at 50 mph.

Is 50 mph a "rate of change of the distance between the gun and the target"?
NO, OF COURSE NOT. It is the SPEED of the target.

Does the speed of the target "equal the rate of change of the distance between
gun and target"? If you are mindlessly obsessed with looking at things that way,
I'm certainly not going to argue with you any further about it. Yes, I suppose it
can be viewed that way.

Ed

El sábado, 4 de junio de 2022 a las 11:54:12 UTC-4, det...@outlook.com escribió:

> >
> > So, I'm asking you (for the 4th time!) for at least one example of a circumstance in which the reading on a simple radar speed gun does *not* equal the rate of change of the distance between gun and target. If you don't know of any such circumstance, then do you agree that my statement is correct, i.e., that this is what a simple radar gun does?
> A radar gun displays "50 mph" when the gun is stationary and it is pointed at
> a target approaching at 50 mph.
>
> Is 50 mph a "rate of change of the distance between the gun and the target"?
> NO, OF COURSE NOT. It is the SPEED of the target.
>

Oh my God. So you do not know that speed v = Δx/Δt ? Δx=distance change; Δt=time measured interval. Therefore, Δx/Δt is rate of change of the distance between gun and target!!!!

On Saturday, June 4, 2022 at 8:54:12 AM UTC-7, det...@outlook.com wrote:
> > > > > > > > > > A simple radar speed gun always just shows the rate of change of the distance between gun and target. A "moving radar" device determines the speed of the gun relative to the ground by measuring the rate of change of the distance between the gun and some object(s) at rest on the ground. There is nothing magical or mysterious about this.
> > > > > > > > >
> > > > > > > > > You are talking about LIDAR guns, not radar guns.
> > > > > > > >
> > > > > > > > Nope, I'm talking about radar speed guns (although the same statement applies to LIDAR speed guns). Again, a simple speed gun reads the rate of change of the distance between gun and target. If you think this is not true, go ahead and describe a situation in which you believe a simple radar speed gun reads something other than the rate of change of the distance between gun and target.
> > > > > > >
> > > > > > > Radar guns...
> > > > > >
> > > > > > I guess you missed my question, so I ask again: Please describe the circumstances in which you believe that the reading on a simple radar speed gun does *not* equal the rate of change of the distance between gun and target.
> > > > >
> > > > > Your question makes no sense.
> > >
> > > > It does make sense, because you've given some examples of what a simple radar gun reads in certain circumstances, and in each of your examples the value you say is shown by the gun equals the rate of change of the distance between the gun and the target... and yet you deny that this is what the value shown on a simple radar gun always equals. So, I'm asking you to tell me at least one circumstance in which the value that shows on a simple radar speed gun is *not* equal to the rate of change of the distance between gun and target. Do you know of any such circumstance?
> > >
> > > I'm talking about how radar guns WORK, and you are talking about how radar
> > > guns can be MISINTERPRETED to work.
> > We can never agree on how a radar speed gun does what it does if we don't agree on what it does. It's well known (and anyone can verify) that the value appearing on a simple radar speed gun is always equal to the rate of change of the distance between gun and target. All the examples you gave confirm this. Note that this isn't an explanation of how the radar gun does what it does, it is simply a statement of what it does. Once we agree on what it does, we can talk about how it does it.
> >
> > So, I'm asking you (for the 4th time!) for at least one example of a circumstance in which the reading on a simple radar speed gun does *not* equal the rate of change of the distance between gun and target. If you don't know of any such circumstance, then do you agree that my statement is correct, i.e., that this is what a simple radar gun does?
>
> A radar gun displays "50 mph" when the gun is stationary and it is pointed at
> a target approaching at 50 mph. Is 50 mph a "rate of change of the distance
> between the gun and the target"?

Yes, of course.

> NO, OF COURSE NOT.

Excuse me? Are you claiming that the distance between run and car is not changing at a rate of 50 miles per hour? What do you think is the rate of change of the distance in this situation?

> Does the speed of the target "equal the rate of change of the distance between
> gun and target"?

No, it doesn't. For example, if that car maintains a constant speed and zooms past you, and you point the speed gun at the car as it is moving transversely to you at 50 mph, the rate of change of distance at that moment is zero, and that is what
the speed gun reads in that condition. This is just a result of the cosine effect (for an angle of 90 degrees in this case), which account for the difference between the speed of an object and the rate of change of the distance.

> Yes, I suppose it can be viewed that way.

Yes, indeed it can. So, we're in agreement that in every circumstance, without exception, the value showing on a simple radar speed gun equals the rate of change of the distance between the gun and the target. Now that we've agreed on what the device does, we can talk about how it does it. This is very simple: It measures the difference of frequencies of the transmitted and returned signal, which depends directly on the rate of change of the distance in accordance with the elementary Doppler effect.

Any remaining questions?

On Saturday, 4 June 2022 at 18:14:42 UTC+2, Paparios wrote:
> El sábado, 4 de junio de 2022 a las 11:54:12 UTC-4, det...@outlook.com escribió:
>
> > >
> > > So, I'm asking you (for the 4th time!) for at least one example of a circumstance in which the reading on a simple radar speed gun does *not* equal the rate of change of the distance between gun and target. If you don't know of any such circumstance, then do you agree that my statement is correct, i.e., that this is what a simple radar gun does?
> > A radar gun displays "50 mph" when the gun is stationary and it is pointed at
> > a target approaching at 50 mph.
> >
> > Is 50 mph a "rate of change of the distance between the gun and the target"?
> > NO, OF COURSE NOT. It is the SPEED of the target.
> >
> Oh my God. So you do not know that speed v = Δx/Δt ? Δx=distance change; Δt=time measured interval. Therefore, Δx/Δt is rate of change of the distance between gun and target!!!!

Oh my God. So yo do not know that it's just a commonm sense prejudice?
Refuted by your bunch of idiots with their inflation idiocy!!!

On Saturday, June 4, 2022 at 10:50:49 AM UTC-5, Paparios wrote:
> El sábado, 4 de junio de 2022 a las 10:26:44 UTC-4, escribió:
> > On Friday, June 3, 2022 at 4:27:31 PM UTC-5, Paparios wrote:
>
> > > Nonsense. Radar guns measure the frequency difference between the transmitted frequency and the received frequency, according to the formula:
> > >
> > > v = (c/2)Δf/fc
> > >
> > > where c is the speed of light, fc is the emitted frequency of the radio waves, and Δf is the difference in frequency between the radio waves that are emitted and those received back by the gun.
>
> > I agree with everything you say, but what you consider to be a "wave" and what I
> > consider to be a "wave" is where we totally disagree.
> >
> Well these few days you have been argueing against Quantum Mechanics, while at the same time you use the photon, which is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force.

I'm not arguing against Quantum Mechanics. Quantum Mechanics works
very well when looking downward and discussing interactions between atoms
and subatomic particles.
Quantum Mechanics, however, does NOT work when looking upward and
describing the universe around us. Quantum Mechanics cannot deal with
the fact that the universe around us is very likely INFINITE. And there are
a lot of other things in the universe around us that Quantum Mechanics
cannot cope with.

>
> From page 476 of the book Radar Technology Encyclopedia, you can read the following:
>
> "With the advent of quantum mechanics, electromagnetic
> radiant energy is seen to be created, destroyed, and transported
> in discrete quanta or photons rather than through a
> continuous transfer of energy implied by electromagnetic
> waves in the classical representation of electrodynamics.
> Because the energy transported by large numbers of photons
> is, on the average, equivalent to the energy transferred in a
> classical electromagnetic wave, for macroscopic applications,
> including radar and communications, Maxwell’s field equations
> are accurate and extremely useful tools".
> > You seem to believe that light travels like water waves spreading away from where
> > a rock is dropped in a pond.
> >
> Wrong, radar signals travel, at the speed of light, as waves which propagate in a very narrow solid angle (determined by the antenna the radar use). See the above text explaining that it is not a single photon but zillions of them traveling like a wave.

That depends upon your definition of a "wave." When the trigger is pulled,
a radar gun emits a STREAM of photons much like water from a hose. There
is NO WAVE PATTERN to the STREAM.

The photons spread out within a 12 degree cone. Individual photons hit
EVERYTHING within that 12 degree cone. When some of them hit a moving
vehicle, those photons are absorbed by atoms in the vehicle. Depending
upon the type of atom, the photon may be absorbed and converted to heat
(like with paint or wood), it might pass through the atom (like with glass),
it might be re-emitted as a NEW photon in some random direction (as with
many other substances), OR it might be re-emitted as a NEW photon back
toward the radar gun (as happens with chrome and silver and mirror-like
substances).

Of all the NEW photons that get sent back toward the radar gun, only a very
tiny fraction will hit the 2 inch circle that is the receiver. Technically, only
ONE returned photon is needed to compute the speed of the target.

> > In reality, experiments hows that light travels as individual PHOTONS, and each of
> > those photons has oscillating electric and magnetic fields which give the individual
> > photon certain "wave like" properties.
> A single photon is a quantum object that has no a precise location. See https://en.wikipedia.org/wiki/Uncertainty_principle

A photon emitted by a radar gun oscillates in a specific frequency range.
Different types of guns use different frequency ranges. When the gun heats
up, the oscillation frequency of the photons changes very slightly. But it is
not enough to affect the operation of the gun, because the photons travel
at the speed of light, making the round trip faster than any significant temperature
change can occur.

The photons travel in a straight line to the target. A tiny few NEW photons will
travel in a straight line from the target back to the gun.

If the "uncertainty principle" is at work during this process, it has no affect on
the workings of the radar gun.
>
> "In quantum mechanics, the uncertainty principle (also known as Heisenberg's uncertainty principle) is any of a variety of mathematical inequalities asserting a fundamental limit to the accuracy with which the values for certain pairs of physical quantities of a particle, such as position, x, and momentum, p, can be predicted from initial conditions".

If the "uncertainly principle" is at work during the operation of a radar gun,
it has no effect on the results.

> > >
> > > From https://en.wikipedia.org/wiki/Radar_speed_gun
> > >
> > > "Radar speed guns, like other types of radar, consist of a radio transmitter and receiver. They send out a radio signal in a narrow beam, then receive the same signal back after it bounces off the target object. Due to a phenomenon called the Doppler effect, if the object is moving toward or away from the gun, the frequency of the reflected radio waves when they come back is different from the transmitted waves. When the object is approaching the radar, the frequency of the return waves is higher than the transmitted waves; when the object is moving away, the frequency is lower. From that difference, the radar speed gun can calculate the speed of the object from which the waves have been bounced".
>
>
> > That is a MUDDLED description. It doesn't say what a radio "signal" is. I would say
> > that "signal" is called a PHOTON. And when it talks about "waves," it would be correct
> > if those "waves" were actually oscillating electromagnetic fields in a photon.
> >
> Total nonsense. A radio signal is an electromagnetic wave of a certain frequency and power.

TOTAL NONSENSE! A radio signal is a PATTERN OF INDIVIDUAL PHOTONS that oscillate
at a specific frequency. "Power" is the NUMBER of photons. A larger number of photons
equals more "power" (or a brighter light) and a smaller number of photons equals less
"power" (or a dimmer light).

AM Radio transmissions involve altering the number of photons in artificially created WAVES
OF PHOTONS - AND THE DURATION OF THOSE WAVES - to cause different sounds in the receiver.

> > LIGHT CONSISTS OF PHOTONS. When you do not talk about PHOTONS and instead
> > talk about signals and beams and waves, all you do is MISLEAD the reader and YOURSELF.
> See above and read those references.
> > > Every light wave can be focussed into a beam (see https://en.wikipedia.org/wiki/Optical_fiber for an extrem example).
>
> > PHOTONS can be focused into a beam. A light "wave" is PART OF A PHOTON.
> What?

A photon consists of electric and magnetic FIELDS that OSCILLATE at a specific frequency.
When viewed from the side, those field oscillations display a wave-like pattern. And the
distance between two crests of electric and magnetic energy fields in that wave-like pattern
is the "wave length."

Ed

On Saturday, June 4, 2022 at 11:14:42 AM UTC-5, Paparios wrote:
> El sábado, 4 de junio de 2022 a las 11:54:12 UTC-4, escribió:
>
> > >
> > > So, I'm asking you (for the 4th time!) for at least one example of a circumstance in which the reading on a simple radar speed gun does *not* equal the rate of change of the distance between gun and target. If you don't know of any such circumstance, then do you agree that my statement is correct, i.e., that this is what a simple radar gun does?
> > A radar gun displays "50 mph" when the gun is stationary and it is pointed at
> > a target approaching at 50 mph.
> >
> > Is 50 mph a "rate of change of the distance between the gun and the target"?
> > NO, OF COURSE NOT. It is the SPEED of the target.
> >
> Oh my God. So you do not know that speed v = Δx/Δt ? Δx=distance change; Δt=time measured interval. Therefore, Δx/Δt is rate of change of the distance between gun and target!!!!

Oh my God!!! So, you do not know that radar guns do NOT measure distance changes??
They ONLY measure oscillation frequency changes between the photons the gun emits and
the photons it receives back! YOU can convert that to a distance change if you want,
but it is NOT what the gun measured! The gun ONLY converts the frequency change into
target speed.

Ed

Ed Lake wrote:

> the fact that the universe around us is very likely INFINITE.

INFINITE???? How far is that?

--
The Starmaker -- To question the unquestionable, ask the unaskable,
to think the unthinkable, mention the unmentionable, say the unsayable,
and challenge
the unchallengeable.

On Saturday, June 4, 2022 at 2:12:38 PM UTC-3, det...@outlook.com wrote:
> On Saturday, June 4, 2022 at 11:14:42 AM UTC-5, Paparios wrote:
> > El sábado, 4 de junio de 2022 a las 11:54:12 UTC-4, escribió:
> >
> > > >
> > > > So, I'm asking you (for the 4th time!) for at least one example of a circumstance in which the reading on a simple radar speed gun does *not* equal the rate of change of the distance between gun and target. If you don't know of any such circumstance, then do you agree that my statement is correct, i.e., that this is what a simple radar gun does?
> > > A radar gun displays "50 mph" when the gun is stationary and it is pointed at
> > > a target approaching at 50 mph.
> > >
> > > Is 50 mph a "rate of change of the distance between the gun and the target"?
> > > NO, OF COURSE NOT. It is the SPEED of the target.
> > >
> > Oh my God. So you do not know that speed v = Δx/Δt ? Δx=distance change; Δt=time measured interval. Therefore, Δx/Δt is rate of change of the distance between gun and target!!!!
> Oh my God!!! So, you do not know that radar guns do NOT measure distance changes??
> They ONLY measure oscillation frequency changes between the photons the gun emits and
> the photons it receives back! YOU can convert that to a distance change if you want,
> but it is NOT what the gun measured! The gun ONLY converts the frequency change into
> target speed.
>
> Ed

The level of ignorance present in this thread is appalling.

The OP was about questioning the perception of time. It derailed quickly about fucking radar guns and, later, what radio
modulation (AM, FM, CW, SSB, etc).

For the fucking morons questioning what radio transmissions are, I advise using (at least) Wikipedia.

For the fucking morons questioning fundamentals on RADAR, I advise the same thing.

RADAR: Radio Detection And Ranging. Since 1930s, it consists in sending MW BEEPS and measuring ECHOES, which turnaround
delay is proportional to DISTANCE.
Doppler RADAR: System developed when electronics allowed the measurement of the difference between the BEEP (pulse) frequency
of the emitting BEEP and the received BEEP. That difference is proportional to the SPEED of the reflecting object PLUS the axial
motion towards the antenna or moving away from the emitting antenna.
3D RADAR: A complex combination of basic RADAR subsystem (at least two antennae, for tracking) plus a DOPPLER subsystem.

Only with the evolution of microelectronics and computer screens, 3D radars started to appear in early '60s. Today, this science is
completely mastered, with multitarget, multibeam 3D composite radar systems (i.e., in AEGIS complex).

Radio modulation, until late 1990s, involved a NON LINEAR control of AMPLITUDE, FREQUENCY or PHASE of a SINGLE RF CARRIER.

A single source of radiowaves, with a SINGLE FREQUENCY, which is non-linearly modulated in any of its three fundamental parameters.

STOP causing shame on others that read this thread, due to the HUGE AMOUNT of ignorance present, Ed.

On 6/4/22 9:26 AM, Ed Lake wrote:
> [to Paparios] what you consider to be a "wave" and what I consider
> to be a "wave" is where we totally disagree.

Right. You have no understanding of what a wave really is, you only
fantasize that you do. Physicists, however, have an excellent
definition: waves are phenomena that obey a wave equation [#].

[This applies to sound, ocean, gravity, salinity,
electromagnetic, and many other types of waves.]

When designing a radar gun, the radar wave is modeled like that from
Maxwell's equations. The configuration of the antenna and the boundary
conditions are arranged so the emitted wave has a narrow divergence,
typically 10-15 degrees. In particular, such designs and their tools
discuss radar waves and beams, with no mention of photons, because they
are not using QED for modeling, they are using Maxwell's equations.

> You seem to believe that light travels like water waves spreading
> away from where a rock is dropped in a pond.

YES, in the domain where Maxwell's equations are valid, in the sense
that "like" means "obeys a similar wave equation", and in the sense that
"believe" means "understand how it is modeled". In particular, this
applies to radar guns. Of course the source terms for a radar gun and a
dropped rock are VERY different, and the boundary conditions for a radar
gun and a pond are also VERY different, resulting in VERY different wave
propagation.

> In reality, experiments hows that light travels as individual
> PHOTONS, [...]

You display your personal lack of understanding of basic physics, and a
complete failure to grasp what science in general is doing. We are NOT
attempting to determine "what light actually is", we are MODELING HOW IT
BEHAVES. For light and related electromagnetic phenomena we have two
excellent models, valid in different (but overlapping) domains:
a) Classical electrodynamics (aka Maxwell's equations), in
which light is modeled as a wave in the (classical)
electromagnetic field.
b) QED, in which light is modeled as a collection of photons,
which are excitations of the (quantum) electromagnetic field.

Note this is not an "either/or" situation, the two models are valid in
different domains, to different accuracies. Radar guns are within the
domains of both models. Since (a) is VASTLY easier to apply than (b),
radar-gun designers all use Maxwell's equations to model their designs.
Indeed it is infeasible to use QED for such designs, as that would
involve N equations, where N is on the order of Avogadro's number.

[#] A wave equation has the form:
d^2/dt^2 F - c^2 Del^2 F = S
where F represents the intensity of the phenomenon, c
is a constant characteristic of the wave, and S is the
source of the wave; the first term is a second-order
partial derivative, and Del^2 is the 3-D Laplacian.

Tom Roberts

On Saturday, June 4, 2022 at 1:16:47 PM UTC-5, The Starmaker wrote:
> Ed Lake wrote:
>
> > the fact that the universe around us is very likely INFINITE.
> INFINITE???? How far is that?

If you are unfamiliar with the word, look it up in a dictionary.
You will see that your question displays MASSIVE ignorance.

Ed

On June 4, det...@outlook.com wrote:
> A radar gun displays "50 mph" when the gun is stationary and it is
> pointed at a target approaching at 50 mph.

What does it read, when the target is stationary, and the
gun approaches at 50 mph?
> Is 50 mph a "rate of change of the distance between the gun and the target"?
> NO, OF COURSE NOT. It is the SPEED of the target.
> Does the speed of the target "equal the rate of change of the distance between
> gun and target"? If you are mindlessly obsessed with looking at things that way,

Mindless indeed.

Now if I open the EdLake Dictionary of Physics, and look
up "speed", or "speed of the target", what definition does it provide?

--
Rich

El sábado, 4 de junio de 2022 a las 13:12:38 UTC-4, det...@outlook.com escribió:
> On Saturday, June 4, 2022 at 11:14:42 AM UTC-5, Paparios wrote:
> > El sábado, 4 de junio de 2022 a las 11:54:12 UTC-4, escribió:

> > > Is 50 mph a "rate of change of the distance between the gun and the target"?
> > > NO, OF COURSE NOT. It is the SPEED of the target.
> > >
> > Oh my God. So you do not know that speed v = Δx/Δt ? Δx=distance change; Δt=time measured interval. Therefore, Δx/Δt is rate of change of the distance between gun and target!!!!

> Oh my God!!! So, you do not know that radar guns do NOT measure distance changes??
> They ONLY measure oscillation frequency changes between the photons the gun emits and
> the photons it receives back! YOU can convert that to a distance change if you want,
> but it is NOT what the gun measured! The gun ONLY converts the frequency change into
> target speed.
>

Sure, the radar detector uses the equation v = (c/2)Δf/fc to infer the target relative speed with respect to the radar emitter, where Δf is the frequency diference between the emitted and received wave frequencies..

Of course that frequency difference (Doppler effect) relates to the distance change between the emitter and the target. If both the emitter and the target are moving, then that frequency difference will give the wrong speed. The correct speed of the target is only obtained when the emitter is at rest (like stationary on the ground).

On June 3, det...@outlook.com wrote:
>>> you display your ignorance in not knowing the difference between a BEAM
>>> and a WAVE.
>>> You cannot focus sound waves into a beam. So, how do you focus light waves
>>> into a beam?
>
>> https://www.fierceelectronics.com/components/choosing-ultrasonic-sensor-for-proximity-or-distance-measurement-part-2-optimizing
>
> That article is about transducers.
> So, if you focus sound waves into a "beam," there is no "beam," there are
> just lower amplitudes of sound the farther you are from the focus point "beam."

oh
There are no beams, just waves with varying amplitudes,
as a function of angle.

A fine distinction indeed.

"Lifeguard, help, I'm drowning!"
"You're mistaken, sir, there's no such thing as drowning, only
varying amplitudes of oxygen flow into the lungs."

--
Rich

On Saturday, June 4, 2022 at 12:20:13 PM UTC-7, det...@outlook.com wrote:
> > So, I'm asking you (for the 4th time!) for at least one example of a circumstance in which the reading on a simple radar speed gun does *not* equal the rate of change of the distance between gun and target. If you don't know of any such circumstance, then do you agree that my statement is correct, i.e., that this is what a simple radar gun does?
>
> A radar gun displays "50 mph" when the gun is stationary and it is pointed at
> a target approaching at 50 mph. Is 50 mph a "rate of change of the distance
> between the gun and the target"?

Yes, of course it is.

> NO, OF COURSE NOT.

Excuse me? Are you claiming that the distance between gun and car is not changing at a rate of 50 miles per hour? What do you think is the rate of change of the distance in this situation?

> Does the speed of the target "equal the rate of change of the distance between
> gun and target"?

No, not in general. For example, if that car maintains a constant speed and zooms past you, and you point the speed gun at the car as it is moving transversely to you at 50 mph, the rate of change of distance at that moment is zero, and that is what the speed gun reads in that condition. This is just a result of the cosine effect (for an angle of 90 degrees in this case), which account for the difference between the speed of an object and the rate of change of the distance.

> Yes, I suppose it can be viewed that way.

Great, so we're in agreement that in every circumstance -- without exception -- the value showing on a simple radar speed gun equals the rate of change of the distance between the gun and the target. Now that we've agreed on what the device does, we can talk about how it does it. This is very simple: It measures the difference between the frequencies of the transmitted and returned signal, which depends directly on the rate of change of the distance in accordance with the elementary Doppler effect. Agreed?

On Saturday, June 4, 2022 at 11:16:47 AM UTC-7, The Starmaker wrote:
> Ed Lake wrote:
>
> > the fact that the universe around us is very likely INFINITE.
> INFINITE???? How far is that?

Infinity is not a number...