Why did solid state electronics replace thermionics?

Question

Why did solid state electronics replace thermionics?

Answer 1

Thermionics is not dead yet.... See article below:

"For most purposes, the vacuum tube has been replaced by solid-state semiconductor devices such as transistors and solid-state diodes. Solid-state devices last much longer, are smaller, more efficient, more reliable, and cheaper than equivalent vacuum tube devices. However, tubes are still used in specialized applications: for engineering reasons, as in high-power radio frequency transmitters; or for their aesthetic appeal, as in audio amplification. Cathode ray tubes are still used as display devices in television sets, video monitors, and oscilloscopes, although they are being replaced by LCDs and other flat-panel displays. A specialized form of the electron tube, the magnetron, is the source of microwave energy in microwave ovens and some radar systems."

http://en.wikipedia.org/wiki/Thermionic_...

Answer 2

Look at your PC. It has many millions of transistors in it.

Now imagine if it used vacuum tubes. A million tubes would take half a city to store, and the power of a large power plant to power, and it would have a time between failures measured in seconds.