LEDS
SemiLEDS Corporation
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So stefan - boltzmann law basically explains how much energy is emitted per a surface area, for a black body. A black body being an object that absorbs all electromagnetic energy that strikes. In laymans terms, how much energy does a body emit. It describes both how much and what type of electromagnetic radiation a system emits. For instance, a black body at 5,772 K produces light [very similar](https://i.sstatic.net/yTUFf.png) to the surface as the sun as the sun is at 5772K. This is why light is described by temperature, as a [7000k Black body peak emissions are bluer than 2500K](http://upload.wikimedia.org/wikipedia/commons/thumb/1/19/Black_body.svg/1000px-Black_body.svg.png) LEDS produce light so efficiently because when excited by electricity they produce narrow bands of light, not all the way through the infrared and shortwave spectrum that we can't see.
It ultimately is an energy balance. If you take the energy radiance from the sun, earth, and moon (anything else is insignificance) apply it a black body, in order for the energy leaving the system to equal the energy entering the system you will arive at a set temperature from the body. Depending on how exactly you arrange the equation, you'll end somewhere just north of 0C. -270C occurs in deep space because how warm is starlight.
Can you design around it? Yes, but there are a couple of problems that are easily observed by looking at the formula:
Total emitted energy = emissivity * Stefan–Boltzmann constant * Temperature^4.
* An emissivity of 1 is found in a black body. Polished perfect reflectors have a low emissivity. If you want to reduce your temperature by changing to a polished reflector, you also are not going to be radiating energy from that surface very well. You want reflective material for objects in the sub because the per surface area the sun input will be greater than your output. And you are going to be absorbing some energy into your system as guess the emissivity of solar panels. Typically spacecraft are solar panels+entirely cladded with reflective material outside of radiators.
* Temperature controls the equation to a power of four. This manisfests in two problems: amount of energy produced and how much it costs to reduce temperature.
Consider top of atmosphere radiation of 1361W/m2 on a 1m2 face of a cube with an emissitivity of 1. From math, energy entering the system is 1361W so temperature leaving the system has to be equal to that. Solving for T, we can see the system would be around -22C. So all well an good right? Just increase the surface radiator and throw and decrease the temperature. Problem 1) internal thermal resistance is a very long way from 0, even if we use copper heatpipes everywhere which makes maintaining even heat difficult. Problem 2) at low temperatures the heat you radiate decreases quarticly. Basically, a 1m2 black body at 273K radiates 315W of power.. A 173K 1m2 black body emits 50W. Basically it gets harder to radiate heat away the colder you are, and it is not a linear relationship. This is further complicated by some components needing a temperature range to operate, and their "cheats" (such as low temperature bit flippng) not following the same sort of relationship as thermal radiation does.
The reason why space "deep space, not around earth or planets" is so "cold" (because tempearture in a vacuum is a dubious concept at best) is because solar radiation is over 6 orders of mangitude more powerful than cosmic radiation.

So stefan - boltzmann law basically explains how much energy is emitted per a surface area, for a black body. A black body being an object that absorbs all electromagnetic energy that strikes. In laymans terms, how much energy does a body emit. It describes both how much and what type of electromagnetic radiation a system emits. For instance, a black body at 5,772 K produces light [very similar](https://i.sstatic.net/yTUFf.png) to the surface as the sun as the sun is at 5772K. This is why light is described by temperature, as a [7000k Black body peak emissions are bluer than 2500K](http://upload.wikimedia.org/wikipedia/commons/thumb/1/19/Black_body.svg/1000px-Black_body.svg.png) LEDS produce light so efficiently because when excited by electricity they produce narrow bands of light, not all the way through the infrared and shortwave spectrum that we can't see.
It ultimately is an energy balance. If you take the energy radiance from the sun, earth, and moon (anything else is insignificance) apply it a black body, in order for the energy leaving the system to equal the energy entering the system you will arive at a set temperature from the body. Depending on how exactly you arrange the equation, you'll end somewhere just north of 0C. -270C occurs in deep space because how warm is starlight.
Can you design around it? Yes, but there are a couple of problems that are easily observed by looking at the formula:
Total emitted energy = emissivity * Stefan–Boltzmann constant * Temperature^4.
* An emissivity of 1 is found in a black body. Polished perfect reflectors have a low emissivity. If you want to reduce your temperature by changing to a polished reflector, you also are not going to be radiating energy from that surface very well. You want reflective material for objects in the sub because the per surface area the sun input will be greater than your output. And you are going to be absorbing some energy into your system as guess the emissivity of solar panels. Typically spacecraft are solar panels+entirely cladded with reflective material outside of radiators.
* Temperature controls the equation to a power of four. This manisfests in two problems: amount of energy produced and how much it costs to reduce temperature.
Consider top of atmosphere radiation of 1361W/m2 on a 1m2 face of a cube with an emissitivity of 1. From math, energy entering the system is 1361W so temperature leaving the system has to be equal to that. Solving for T, we can see the system would be around -22C. So all well an good right? Just increase the surface radiator and throw and decrease the temperature. Problem 1) internal thermal resistance is a very long way from 0, even if we use copper heatpipes everywhere which makes maintaining even heat difficult. Problem 2) at low temperatures the heat you radiate decreases quarticly. Basically, a 1m2 black body at 273K radiates 315W of power.. A 173K 1m2 black body emits 50W. Basically it gets harder to radiate heat away the colder you are, and it is not a linear relationship. This is further complicated by some components needing a temperature range to operate, and their "cheats" (such as low temperature bit flippng) not following the same sort of relationship as thermal radiation does.
The reason why space "deep space, not around earth or planets" is so "cold" (because tempearture in a vacuum is a dubious concept at best) is because solar radiation is over 6 orders of mangitude more powerful than cosmic radiation.