The light bulb conspiracy is a theory that the leading manufacturers of incandescent light bulbs have conspired to keep the lifetime of their bulbs far below their real technological capabilities. This way, they ensure the continuous demand for more bulbs and hence, long-term profit for themselves.
The incandescent light bulbs were invented by British chemist Humphry Davy in 1809, however, it wasn't until Thomas Edison found a way to mass produce them that their commercial use began. In 1924, the leading light bulb manufacturers formed the international Phoebus cartel with the intent to standardize the light bulbs (e.g. the E27 connectors), which was officially disbanded in 1939.
Conspiracy theorists suspect that the primary goal of Phoebus was not to develop international standards but instead, to sink the lifespan of all light bulbs. It was noted that before 1924, said life expectancy was slightly above 2000 hours. To increase the demand and hence, their profit, Phoebus members agreed to halve the life expectancy of all their bulbs by using lower-quality materials and production methods. The life expectancy was conducted gradually until the cartel's dissolution to avoid drawing public attention.
Although Phoebus was disbanded in 1939, say the theorists, its influence is still felt in the West. By comparison, Soviet light bulbs and those produced in socialist countries (which didn't adhere to Western standards) have been noted to have a twice as long lifetime. Modern Chinese bulbs have a life expectancy of 5000 hours. Moreover, light bulbs produced in Britain during or immediately after World War II, when the patriotic feelings could take over commercial interests, are still found in use to this day. These "ancient" light bulbs are sought after by manufacturers, who remove them from circulation "for study". The oldest lamp in the world, "Centennial Light", has been in use for 116 years, as of 2018.
Attempts have been made in Europe to circumvent the standards set by Phoebus. In 1975, German watchmaker Dieter Binninger invented a light bulb with life expectancy of 150,000 hours (in other words, 17 years of continuous use!). However, shortly after finally finding a manufacturer for his bulbs in 1991, Binninger died in a plane crash, which was officially regarded as an accident. His patent has since sunken into obscurity and oblivion. A quick look at Binninger's Lamp Patent indicates experiments using Traffic-Light bulbs that were underrun. A 230V bulb was run at 120V certainly extended its lifespan to the order of 100,000 hours, but had the effect of making the light produced more orange/yellow in spectrum, and less of it.
Incandescent bulbs all use a tungsten filament. A hotter filament is more efficient but burns up more quickly. It is very simple to make a bulb last forever: use a longer and thinner filament, which does not get as hot, and glows more red than white. A bulb will also last forever if you simply put it on a dimmer and dial it way down. But there is an unintended consequence. A standard 100 watt bulb costs 50 cents, lasts 1500 hours, and uses $18 in electricity over that time (at 12 cents per kWh). The new everlasting bulb will use about 3 times as much electricity over its first 1500 hours, costing an extra $36 to save a half dollar. And another $36 for the next 1500 hours. This is about $200 per year more than the standard bulb which is designed to burn out quickly and save money. The money saved represents a large quantity of coal or natural gas that would be burned to save a few little bulbs.