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MIT's Millimeter Turbine to be Ready This Year
Iddo Genuth writes "After a decade of work, the first
millimeter size turbine engine developed by researchers at MIT should become operational by the end of this summer. The new turbine engine will allow the creation of smaller and more powerful batteries than anything currently in existence. It might also serve as the basis for tiny powerful motors with applications ranging from micro UAVs to children's toys. In the more distant future huge arrays of hydrogen fueled millimeter turbine engines could even be the basis for clean, quiet and cost effective power plants."
Imagine a, oh, whatever, cluster of these!..
In Soviet Washington the swamp drains you.
Doesn't turbines get more efficient as they grow in size? I mean, it's not like you'll see power plants use hundreds of tiny steam turbines - they use a few huge ones.
Or am I missing something completely fundamental about the ones MIT's made here?
We do not live in the 21st century. We live in the 20 second century.
This is all well and good but what about all the little bugs that will get shredded in those little turbines? Are they going to paste millimeter-size warning signs? I think it's the least we could do for our tiny houseguests.
Millimeter Turbins? Must be for really small Muslims.
Have you read my journal today?
Even a thousand whispers can get pretty loud
I beg to differ. Wikipedia lists the sound pressure level of a whisper at 20 dBs. To calculate the sound of a thousand people whispering, we need to do 20 times log10(ratio). The ratio is 1000 whispers to one. log10 of 1000 is 3, so the SPL level of a thousand people whispering is only 3 time 20, or 60 dBs.
However, though wikipedia does not state at what distance the SPL level of a whisper was measured, usually we would imagine that it would be a person standing right next to us, or certainly within a meter. Clearly you cannot have a thousand people standing right next to you. Even within a meter of you, considering perhaps two people per square meter including yourself, within a circle of a one meter radius you have only about 3 square meters - room for 5 people besides yourself at the centre. To accommodate a thousand people, you would need a circle with a radius of over twelve meters. Most of those people are going to be at least 6 meters away from you. Wikipedia says "Note that the SPL emitted by an object changes with distance d from the object with 1/d.", so that implies that well over half of these people only contribute a fraction of their potential to the total sound level.
Beyond that, we have all these whispers generating an incoherent pattern of sound waves, sometimes reinforcing each other, and sometimes cancelling each other out, such that by the time this reaches your ears it has only a fraction of the energy that it would posses if everybody whispered in absolutely perfect unison, offset by their distance from you. In the end, the total SPL level is beyond my capability to calculate, but I would just guess that on a practical level it would not reach the level of a normal conversation between two people.
Now, if you want to hear something loud, consider the sound of a thousand hands clapping. Going by the previous example, it is easy to calculate. We begin with an estimate of the sound pressure level of one hand clapping... Oh oh...