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Simple streetlight hack could protect astronomy from urban light pollution

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Re: Simple streetlight hack could protect astronomy from urban light pollution

#151

Post by calamari4065 »

anon_cow1111 wrote: post #96
calamari4065 wrote: post #87

Earlier quoted context omitted.

Okay, let's do some math. Very rough napkin numbers, but it'll get us close. A 150Hz blink rate means a period of 1/150s, or ~6.7ms. The speed of radio signals through air near the surface is a bit lower than c, let's call it 299,250 km/s. [0] When you multiply those numbers you get ~1500km. That means each 'on' and 'off' signal is 1500km long, moving near c. More specifically, the signals are concentric rings around…

>Let's look at London. I picked it at random, but it just happens to have a land area around 1500km^2 Um am I really really tired and not reading correctly, or is this confusing linear area with square area? London doesn't stretch from New york to Florida. 186000 miles/second * pulse of .003 = 558 miles ~= 900 km

I knew I fucked something up. Don't do math while smoking, kids.

Either way, propagation delay is a huge problem with synchronizing systems. It's not something you usually think about

Re: Simple streetlight hack could protect astronomy from urban light pollution

#152

Post by calamari4065 »

peddling-brink wrote: post #148
calamari4065 wrote: post #87

Earlier quoted context omitted.

Okay, let's do some math. Very rough napkin numbers, but it'll get us close. A 150Hz blink rate means a period of 1/150s, or ~6.7ms. The speed of radio signals through air near the surface is a bit lower than c, let's call it 299,250 km/s. [0] When you multiply those numbers you get ~1500km. That means each 'on' and 'off' signal is 1500km long, moving near c. More specifically, the signals are concentric rings around…

I’m not a physics person, but couldn’t this be easily solved by adding a programmed delay that corresponds to the distance from the transmitter? Street lights aren’t known to migrate.

In principle, yes. But not easily.

The physics of radio wave propagation are surprisingly complex. Buildings and objects in the path between transmitter and receiver can cause various interference effects that basically slow down the signal. I'm glossing over a lot, but it would take significant effort to precisely measure the exact delay between any one receiver and the transmitter. It's much more complicated than just the distance, and each one has to be measured individually.

I'm not an expert in RF, but I think this concept of a single synchronizing transmitter just doesn't work in the real world. You'd probably build a cell network with many transmitters covering small areas. Each transmitter has the hardware to synchronize with thr others, and the lights just have a simple circuit slaved to the transmitter clock.

There's probably more clever ways to synchronize signals over long distances, but RF is black magic to me.

Re: Simple streetlight hack could protect astronomy from urban light pollution

#153

Post by calamari4065 »

namuol wrote: post #121
calamari4065 wrote: post #87

Earlier quoted context omitted.

Okay, let's do some math. Very rough napkin numbers, but it'll get us close. A 150Hz blink rate means a period of 1/150s, or ~6.7ms. The speed of radio signals through air near the surface is a bit lower than c, let's call it 299,250 km/s. [0] When you multiply those numbers you get ~1500km. That means each 'on' and 'off' signal is 1500km long, moving near c. More specifically, the signals are concentric rings around…

There’s engineering feasibility, and then there’s feasibility. Is it any less feasible to operate fewer or dimmer street lights? How about directing light more efficiently? This is a problem of bureaucratic and societal engineering.

I was really just exploring a hypothetical. This whole idea of synchronizing lights is pretty dumb. It won't work, and even if it did it's still a bad solution.

Better solution is less lights, or turn them off at night or any of the other solutions we've been talking about for 30 years. Remember when street lights were killing sea turtles?

Re: Simple streetlight hack could protect astronomy from urban light pollution

#155

Post by Doxin »

Obscurity4340 wrote: post #145
rickydroll wrote: post #144

Earlier quoted context omitted.

2800k LEDs are not filtered white light afaik. A bit of background for those who may not be aware, white LEDs are UV LEDs with a white light emitting phosphor. I suspect 2800 K LEDs are a UV LED with a 2800 K light-emitting phosphor.

Whats the orange one? I've seen pics of streetlamps like that unless its a MandelaEffect or somethint

You might be thinking of sodium vapor lights

Re: Simple streetlight hack could protect astronomy from urban light pollution

#156

Post by Obscurity4340 »

Doxin wrote: post #155
Obscurity4340 wrote: post #145

Earlier quoted context omitted.

Whats the orange one? I've seen pics of streetlamps like that unless its a MandelaEffect or somethint

You might be thinking of sodium vapor lights

Yes! Why doesn't everyone just use these? Where there's astronomical concerns or people agree its just a nice and worthwhile end to be able to see the night sky, maybe use the low-pressure sodium but yeah.

Edit: I wonder what gets used in "rich" places in contrast to "poor" places. I feel like rich people get the night sky and poor people get headaches and insomnia. So sick of this shit

Re: Simple streetlight hack could protect astronomy from urban light pollution

#157

Post by Obscurity4340 »

Zardoz84 wrote: post #128
Obscurity4340 wrote: post #120

Earlier quoted context omitted.

Its often the most offensive shade of bright white fluorescent-like LED. Why can't they do the orange one that lets everyone be ok seeing light at night and sleeping to tell the tale

LED it's more power efficiencient . However, there are LED light bulbs that have some kind of filter that makes it more ambient and astronomy friendly. Normal white LEDs are a nightmare for astronomy, because his light spectrum it's hard to block with any kind of "anti light pollution" filters.

Is there any correlation between wealthy districts and poor districts in terms of type of light used? I feel like everyone would want to accomodate the rich areas and make sure they can see the night sky and sleep and not have the unpleasent "poor" flurorescent/led "cost-savings" light

Re: Simple streetlight hack could protect astronomy from urban light pollution

#158

Post by op00to »

mumblemumble wrote: post #89
op00to wrote: post #62

Earlier quoted context omitted.

Why not?

Even flicker that isn't perceptible to humans is still associated with increases in all sorts of things including eyestrain, headaches, anxiety, migraines, and seizures. 150Hz is well below the human perceptual threshold but still within the range that can cause problems.

Thank you!

Re: Simple streetlight hack could protect astronomy from urban light pollution

#159

Post by sand500 »

calamari4065 wrote: post #151
anon_cow1111 wrote: post #96

Earlier quoted context omitted.

>Let's look at London. I picked it at random, but it just happens to have a land area around 1500km^2 Um am I really really tired and not reading correctly, or is this confusing linear area with square area? London doesn't stretch from New york to Florida. 186000 miles/second * pulse of .003 = 558 miles ~= 900 km

I knew I fucked something up. Don't do math while smoking, kids. Either way, propagation delay is a huge problem with synchronizing systems. It's not something you usually think about

Dont you have propagation delay in reverse too? Let's say you do turn off all the lights at the exact same time. The light hitting the telescope also travels at the speed of light.
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