Heater
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Re: Snarky non-responses to questions

Fri Mar 10, 2017 6:28 pm

OK, who was it? Who said I was wrong?

I'm not wrong. The question about Johnny and his laser is incomplete and ambiguous.

There are many answers depending on how you interpret the question.

Hence my asking "Who is the observer?"

An interpretation was suggested and I gave the the right answer for that interpretation.

Now, what if Johnny is a blind duck? What colour is the laser then?
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bensimmo
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Re: Snarky non-responses to questions

Fri Mar 10, 2017 6:38 pm

It's still the same colour laser as described and designed.
Being able to see it does not alter that.

A UV or IR laser is still a UV or IR laser, yet you cannot see it light unless you manipulate the frequency of said lasers light, be it frequency doubling or flying in a spherical spaceship in a Vacuum or having it flourese of something or some thin film interference.

And how did we get to half c in a spaceship?


The ambiguity I hope was intentional, as are many questions on the Pi and Pixel.
Last edited by bensimmo on Fri Mar 10, 2017 6:44 pm, edited 2 times in total.

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rurwin
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Re: Snarky non-responses to questions

Fri Mar 10, 2017 6:41 pm

bensimmo wrote:Especially as an 850nm wave is infrared, so somebody made your red laser wrong, i would complain to the manufacturer.
:roll:


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k-pi
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Re: Snarky non-responses to questions

Fri Mar 10, 2017 7:20 pm

Snarky non-responses to questions - well most of this thread is totally irrelevant to the original post! :lol:

blaablaaguy
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Re: Snarky non-responses to questions

Fri Mar 10, 2017 7:20 pm

bensimmo wrote:The laser is red, it always will be, it's in its name 'red laser'*
What people observe the photons as may not be interpreted as red.
But the laser doesn't change.


*Unless it has the wrong label.


Imagine a Pi in a box...
I have no idea what the doppler shift is, and probably dont know what im talking about but... i agree with this guy
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Re: Snarky non-responses to questions

Fri Mar 10, 2017 7:30 pm

Doppler shift is the excuse you give to the judge when you are caught driving through a red traffic light.
Of course you will likely get fined for speeding instead. ;)

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hansotten
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Re: Snarky non-responses to questions

Fri Mar 10, 2017 7:33 pm

k-pi wrote:Snarky non-responses to questions - well most of this thread is totally irrelevant to the original post! :lol:
Agree, this topic is now completely offtopic!

Where are the moderators, so active always to close or remove topics .?.
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Re: Snarky non-responses to questions

Fri Mar 10, 2017 7:37 pm

bensimmo
It's still the same colour laser as described and designed.
Being able to see it does not alter that.
Many people, including myself, would argue with that.

It may be said that a laser has some measurable frequency or wavelength that is always constant, in it's frame of reference.

Colour on the other hand is an experience of the observer. It is subjective. If there were no humans or other sentient beings that could see light there would be no such thing as colour at all.

Have you never heard of the old question "If a tree falls in the forest and there is nobody there to here it, does it still make a sound?"
A UV or IR laser is still a UV or IR laser, yet you cannot see it light unless you manipulate the frequency of said lasers light, be it frequency doubling or flying in a spherical spaceship in a Vacuum or having it flourese of something or some thin film interference.
Not true.

Einstein gave us the theory of relativity. The end result of which is that if you are running away from a UV light source fast enough it's frequency will be lowered as far as you are concerned. At the right speed it's wavelength will be shifted such that you can see it.

That idea is a hundred years old. Try to keep up :)
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Re: Snarky non-responses to questions

Fri Mar 10, 2017 8:17 pm

This is why we can't have nice things :|

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bensimmo
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Re: Snarky non-responses to questions

Fri Mar 10, 2017 8:25 pm

Heater wrote:bensimmo
It's still the same colour laser as described and designed.
Being able to see it does not alter that.
Many people, including myself, would argue with that.

It may be said that a laser has some measurable frequency or wavelength that is always constant, in it's frame of reference.

Colour on the other hand is an experience of the observer. It is subjective. If there were no humans or other sentient beings that could see light there would be no such thing as colour at all.

Have you never heard of the old question "If a tree falls in the forest and there is nobody there to here it, does it still make a sound?"
A UV or IR laser is still a UV or IR laser, yet you cannot see it light unless you manipulate the frequency of said lasers light, be it frequency doubling or flying in a spherical spaceship in a Vacuum or having it flourese of something or some thin film interference.
Not true.

Einstein gave us the theory of relativity. The end result of which is that if you are running away from a UV light source fast enough it's frequency will be lowered as far as you are concerned. At the right speed it's wavelength will be shifted such that you can see it.

That idea is a hundred years old. Try to keep up :)
I think you miss understand, a laser is a device, light is something else that comes out of a laser.
A tap is not the same as water.

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Re: Snarky non-responses to questions

Fri Mar 10, 2017 8:46 pm

You are right. I do not understand you. I thought the conversation was about the visibility/colour/frequency of light emitted by a laser on a space ship.
Memory in C++ is a leaky abstraction .

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bensimmo
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Re: Snarky non-responses to questions

Fri Mar 10, 2017 9:07 pm

It was about snarky responses, I've forgotten how we got this far. :geek:

But..
Johnny is in space ship traveling at half light speed, he shines a red laser at a spaceship going the other way, what colour is the laser?

The laser is red, it will still be red. There is nothing there about the light coming out of it.
A blue ball will still be a blue ball .. or will it?

It all goes to show how complicated interpretations can be.

You went down assumption a laser is the light, or was meant to be the light. Perhaps thought laser beam as it's commonly called.
Someone assumed Johnny was the observer since no other person was mentioned.

(None of this is helped with by my poor phone screen typing skills/lazyness)


Anyway back to Pi's for me (in a box with a heatsink or not)

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Re: Snarky non-responses to questions

Fri Mar 10, 2017 10:00 pm

Heater wrote: it's frame of reference.
it's frequency will be
it's wavelength will be shifted
That idea is a hundred years old. Try to keep up :)
Must not post snarky response.

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Gavinmc42
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Re: Snarky non-responses to questions

Sat Mar 11, 2017 11:35 am

The question about Johnny and his laser is incomplete and ambiguous.
There are many answers depending on how you interpret the question.
Hence my asking "Who is the observer?"
Wow, must bring out Johnny and his laser more often.
Heater did get the point, I knew who the observer was but did not make that clear.

Obviously Johnny, if he is inside and there is no space dust will not see his laser.
Aiming a laser in space at half C at another spaceship which is traveling at ?C.
Assuming they are moving directly towards each other the light will blue shift.
If the other spaceship is stationary and Johnny is heading directly towards it then the wavelength is half, if the red laser is 650nm then the observer is going to see 325nm ultraviolet.
If Johnny is not going directly towards the observer ie cop on the side of the road.
Will it be exactly 325nm the cop sees? Can he then work out what speed Johnny is going?

Asking clear questions is the point, but then providing full information and reference points is the point.

It also depends on perceptions, I know other peoples perception of what I see as a little bit orange they see as yellow. Is my perception wrong or are they wrong? It's not my fault they have faulty colour perceptions :?

Our perception of what we want and what we think other people want is based on our own experiences. Everyone sees the world differently.

If a noob or someones asks a question and we choose to reply we have to be careful and don't assume they did not ask the wrong question, know what they are asking or are lazy and have no clue or any other interpretation we choose to assume. Huh!

We cannot see the person asking the question so we miss facial clues and get stuck with using emoji's. But sometimes it's bloody obvious they have no clue or maybe they are stuck in a wheelchair and have to type by moving their eyeballs and hence hate long questions :shock:

Be nice people.
That kid could be programming your car in 15 years time and might remember you.

The RPF is providing us nice toys and they are about Education.
If we choose to be here then we are part of that education system.
Too bad we just cannot throw dusters at the people who ask stupid questions :lol:

But it does not matter anyway because we don't exist and are mostly empty space affected by quantum fluctuations.

I reserve the right to change my opinions at any time, I might just be wrong.
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Heater
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Re: Snarky non-responses to questions

Sat Mar 11, 2017 12:43 pm

stderr,
Must not post snarky response.
Slap. Ouch! I must not post snarky responses. I must not post snarky responses. I must not post snarky responses....

I do try to behave myself. No really. It's just that sometimes my schoolboy humor take me over.
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rurwin
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Re: Snarky non-responses to questions

Sat Mar 11, 2017 1:54 pm

Gavinmc42 wrote:If Johnny is not going directly towards the observer ie cop on the side of the road.
Will it be exactly 325nm the cop sees? Can he then work out what speed Johnny is going?
The only velocity that matters is that component that is radial to the cop. You can work it out with sines and cosines and Pythagoras, but the answer is always below your total velocity. Therefore if the cop sees you speeding, you are always going at least that speed and maybe significantly more..


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321
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Re: Snarky non-responses to questions

Sat Mar 11, 2017 4:22 pm

So how do you know the speed measuring device has taken its readings from the same part of the vehicle?

The avg car length at 2.1metres is + or - 30mph's during the 0.3 second time period used to emit 3 laser pulses in order to calculate a speed reading.

I'm sure the detector on the laser speed measuring device is colour blind, in that it can only detect light frequencies in a certain range close to the laser light that is emitted. In other words not detecting light in the human visible light frequency range or UV/Xray part of the spectrum, and whilst it can detect laser light in a certain frequency, its still treated by the algorithm as a binary value.

I'm also sure it can only detect light intensity (lux), and are weaker in strength than what you find in your optical disc player or supermarket checkout, so knowing that light intensity can vary due to the angle of incidence, how can we be sure the speed measuring device is accurate? Even barcode readers interpret the bars reflection within a certain range when normalised against the others it detects in a certain time frame that matches what an operator takes to scan/wave a product over the checkout.

On top of that, how do you know the detector is working in the right time frame considering the variability of power and delay in power reaching all circuits? An example of this which everyone can see, is watching the brake lights come on from the car in front.

If you are quick enough and concentrating enough, you can see the LED central brake light come on first, followed very very quickly by the right or left brake light which ever has the shortest circuit/run inside the car, followed by the opposite side brake light at the furthest part of the circuit/run.

Likewise I know we have mains that is 240volts, but my little battery backup tells me, this can vary as can the current, and although batteries are used to smooth these power fluctuations in these devices, I know ambient air temperate also affects voltage, when I put flat batteries onto of a radiator to squeeze the last bit of chemical reaction out of them.

We also know that cpu's can operate at different timings depending on their temperatures, one example being, taking the heatsink off an AMD cpu and it will freeze & crash when the cpu get too hot, ARM and Intel clock back the cpu speed to compensate and minimise damage to the CPU, even though loop based OS's when suggesting their CPU's are only x% busy are still switching away at the same rate regardless of workload. The fact CPU's can alter their clock speed just obfuscates that fact.

Plus we also only need a 1 degree difference in air temperature and a surface to create a heat haze, best seen on roads, and we know heat hazes affect light, so can even light then be treated as a constant when measuring speed of something on a road?

We also know light speed is not constant when passing through some objects although to be fair you wont find the most obvious one on the roads or when bolling up to space ship, but you will in a lab.

Sometimes it pays to read the patent.

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Re: Snarky non-responses to questions

Sat Mar 11, 2017 4:41 pm

The more important question is, "Is the cat dead?".
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321
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Re: Snarky non-responses to questions

Sat Mar 11, 2017 4:47 pm

Ask Schrödinger.

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Re: Snarky non-responses to questions

Sat Mar 11, 2017 4:55 pm

It pulses light in the nanoseconds and receives the reflection. It calculates the time it has taken to travel.

It would then repeat this hundreds/thousands of times and use that data to calculate an average speed, removing erroneous measuments. The time period for this is short and can be repeated and easily within you 300us.

A sensor can be narrow or broad range they will know what to use and select one specific to the task.

Maybe they have better ways.

Nothing to stop you manipulating the reflection.


Which patents are you looking at, LTI? I've not read any of them as it's been of no interest.

321
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Re: Snarky non-responses to questions

Sat Mar 11, 2017 5:04 pm

LTI, if its still online, only 3 pulses, speed readings can be obtained from a stationary object by sweeping the device along a fixed object like armco barriers or court room walls if the court room is big enough. The patent even admits it can get a speed reading from a stationary object! ;-)

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Re: Snarky non-responses to questions

Sat Mar 11, 2017 5:09 pm

321 wrote:the 0.3 second time period
bensimmo wrote:within you 300us
Oh dear. :?
0.3s = 300ms = 300 000μs. :o :shock:

Also note Latin "u" is not the same as Greek "μ". :ugeek:

If I'm being too snarky (snarly? narky? -- thanks spell check ;) ) or OT :roll: , perhaps this thread will finally get the lock I think it deserves :x
No criticism of the 8-) mods implied. :)
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Re: Snarky non-responses to questions

Sat Mar 11, 2017 5:13 pm

davidcoton wrote: Oh dear. :?
0.3s = 300ms = 300 000μs. :o :shock:

Also note Latin "u" is not the same as Greek "μ". :ugeek:

If I'm being too snarky (snarly? narky? -- thanks spell check ;) ) or OT :roll: , perhaps this thread will finally get the lock I think it deserves :x
No criticism of the 8-) mods implied. :)
If I were a mod on here, I'd lock this thread for your excessive use of Smilies (aka emoticons aka emoji).
Note: Having anything humorous in your signature is completely banned on this forum. Wear a tin-foil hat and you'll get a ban.

Any DMs sent on Twitter will be answered next month.

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CarlRJ
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Re: Snarky non-responses to questions

Sat Mar 11, 2017 6:13 pm

DougieLawson wrote:The more important question is, "Is the cat dead?".
Yes.
And no.

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Re: Snarky non-responses to questions

Sat Mar 11, 2017 6:33 pm

davidcoton wrote:
321 wrote:the 0.3 second time period
bensimmo wrote:within you 300us
Oh dear. :?
0.3s = 300ms = 300 000μs. :o :shock:

Also note Latin "u" is not the same as Greek "μ". :ugeek:

If I'm being too snarky (snarly? narky? -- thanks spell check ;) ) or OT :roll: , perhaps this thread will finally get the lock I think it deserves :x
No criticism of the 8-) mods implied. :)
Unbelievably, given my poor phone typing, English (British) is my first language. The rest is just Greek to me and therein lies the problem.

Or i just typed the u instead of m by accident ;-)
I hold my hand up in shame.

And where is the micro symbol on a Google keyboard (Gboard) in British English setting. It is not above u.
I can find odd character ౽౬, arrows ↑ † crucifix ,wandering finger gestures, santa heads.
But no standard everyday Greek symbols.

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