Shouldn’t the vacuum insulate the glass from the heat of the burning filament?
Why does the sun heat the Earth if space is a vacuum?
Because of me. Whenever I look up at the sun, I think about the inevitable supernova which the sun sooner or later will turn into. This in turn gives me anxiety and makes me sweat a lot, which heats the earth.
Correct me if I’m wrong but isn’t the sun too small to turn into a supernova? and basically will just die a boring death after swallowing all the planets in the solar system and fade into nothingness
A new worry has been unlocked: We’re all going to die but not in a cool way and all the other solar systems will think we’re lame.
basically will just die a boring death after swallowing all the planets in the solar system
Not all the planets, no. Mercury and Venus, sure. The earth’s orbit will move somewhat further out when the sun expands, and probably won’t be swallowed but it will at least be well baked.
Not quite that large. At the peak of its red giant phase, the sun’s size will reach just about Earth’s current orbit. Quite possibly the Earth will remain just slightly outside the sun due to the orbit becoming larger to compensate for the sun’s decreasing mass, but the Earth’s oceans will have boiled off before the sun even enters its red giant phase, because between now and then the sun will get progressively hotter over the millenia (well, technically this slow increase in average sun temperature has been going on for ages already, it’s just really slow and masked by several cycles).
Vacuum means no convection heat. It however does not mean no radiation heat. The filament radiates heat through vacuum the same way the sun does.
Additionally, theres not vacuum in buldbs, but inert gas, like argon.
There no longer is a vacuum in bulbs, but there was for a very long time.
“Halogen” bulbs are just incandescent bulbs filled with inert gas and a small amount of bromine or iodine. Very interesting chemistry https://en.wikipedia.org/wiki/Halogen_lamp
In addition to the stuff everyone else is saying, most modern bulbs don’t have a vacuum at all.
Most modern bulbs are filled with an inert gas like argon or xenon. Usually at a lower pressure (around 70% of standard atmospheric pressure), but nowhere near a vacuum.
This has, while inert to chemical reaction, is more than capable of transferring heat.
Heat is infrared. Light. Vacuum doesn’t have much effect.
Also many bulbs are filled with inert gases rather than being vacuums.
Heat is infrared. Light.
All light heats up anything that absorbs it. This includes infrared, but it also includes visible light, microwaves, radio waves, etc. You can get a nasty burn from putting your hand near a live radio transmitter antenna, for example, even though it’s emitting in RF, not infrared.
In addition, all physical objects glow with a light that is determined by their temperature. This includes your body. You are, right now, emitting light. As it happens, because of your body’s temperature, that light is mostly in the infrared.
Why do kids’ science books leave you with the impression that “heat is infrared”? Because you can see body heat with an infrared camera. Infrared is light that you can’t see with your eyes — but with the right tool, you can use to see body heat. This rounds off to “heat is infrared”.
Heat is not infrared. All physical objects emit light; objects around human body temperature glow mostly in the infrared; which we can’t see with our eyes, but can see with scientific instruments. And when an object absorbs light (including infrared), it gets hotter.
very closely related:
If I super heat a metal and it turns visibly red what is happening? Was it already emitting infrared and as it gets hotter the frequency shifts up? Or is it still emitting infrared but has a wider band of frequencies it is emitting as well (i.e. is it emitting frequencies below infrared as well as visible red)?
Yes, as you heat something up to “red hot”, the glow shifts from infrared to being partly in visible red frequencies. This is why a blacksmith can use the color of a piece of hot iron to tell how hot it is.
https://en.wikipedia.org/wiki/Black-body_radiation
(This isn’t the only way hot things make light, though — for instance, flames can glow with odd colors like green or blue due to specific chemicals burning.)
Same way sun heats the earth
