what factors led to a wide acceptance of darwins theory?
The easy answer is that Darwin was right.
Even before Darwin was born, it was known that creatures evolved. Geologists had noticed a strange occurrence, the fossils they dug out of the ground at the deepest (and oldest) strata were far simpler than the fossils dug out of the shallower (and younger) levels of strata, not only that, but certain features appear in fossils from a certain strata, then the later fossil seem show a gradual improvement of these features. The little writing which is left of Robert Hooke's work, (the rest of which was destroyed by a jealous Isaac Newton) reveals that he was convinced that creatures evolved over a period of time. Lamarck came up with a theory which attempted to explain how this development came about, suggesting that a giraffe who continually stretched his neck higher and higher for the leaves in the tree would actually grow a longer neck and then this attribute would be passed onto the next generation. Unfortunately, it didn't explain how people who had lost limbs still had children who were fully formed.
What Darwin did was nothing more than provide the mechanism to explain the increasing complexity over time. Darwinian Natural Selection is the very epitome of the scientific theory, simple and elegant yet incredibly powerful. It is consistent with all scientific principles and tools as yet developed, and not only that, through all the scientific revolutions that have occurred since, (quantum, genetic, medical, Einsteinian and astro-physical, to name a few) Natural Selection has never been challenged, but has only ever been lent more support by the emergent fields. The fact that this theory by a Victorian Botanist, easily summed up the sentence "The non-random selection of randomly varying replicators" has been so strengthened our emerging understanding of the universe and remains consistent with the cutting edge science and the truths he could never have even imagined, is powerful proof it's veracity and the scientific community would have to deny the very nature of science to deny Darwin.
Lighting Up Your Home With Leds: is it Time to Upgrade?
Increasingly consumers are turning their eyes towards LED house lights as a way to conserve electricity. But will you really achieve the greatest savings by buying this still expensive lighting now? Or would you be better off to save your money for the time being, or to buy other energy-efficient light bulbs, and use the money you save in electricity to buy LED house lights down the road?
You have most likely seen LEDs before: camping headlamps, LED Christmas tree lights, wind-up emergency torches. How about LED house lights? If LEDs are so efficient, why aren't manufacturers lining up to sell LED lights for the home, and why aren't we lining up to buy them?
I wouldn't try to sell you on LED lights as a solution to high utility bills or as the most ecologically beneficial lighting solution around. Frankly, I think LEDs have a ways to go yet, in terms of function, durability, and economy. There are some LED products you should consider over the next year, such as LED Christmas lights. And you might enjoy trying out a couple of LED light bulbs, if you're the energy-saving type. But you are going to save more money by keeping with your current lighting, and migrating to fluorescent lights in the next year or so. Compact fluorescent lights, or CFLs, have a payback so short that they'll pay for themselves before LEDs have matured enough to make CFLs out of date.
LED light bulbs are more efficient than incandescent or fluorescent lighting. The problem is that LEDs have very directed light. An incandescent light shines over a wide area fairly evenly, while LED lights are very focused, so that the area they directly illuminate is very bright, while the further you go from the direct beam, the less light there is. For LED Christmas lights, that isn't a problem; you just want some shining points of light, which LEDs do very efficiently. But an incandescent or CFL will do a much better job of brightening up your living room than an LED bulb in the same application. The light will be more evenly and broadly spread, and with a warmer color.
When you see LED packaging claims of LED light output, you should be doubtful. A number in Lumens, which indicates light brightness, is misleading for LEDs, because of their focused beam. Lumens levels are read from a sensor placed right underneath the light source. A household LED light bulb at 2 watts may have the same lumens rating as a 50 watt halogen bulb, or as a 15 watt CFL, but the LED lamp may only send a focused light directly under it to the photo sensor, while the incandescent light and CFL will light up a much broader area, and still give that same lumens rating for the area immediately beneath the bulb. This may be the source of a frequent negative comment among LED owners, such as: "The packaging claims this 2-watt LED bulb has the same light output as a 50-watt incandescent bulb but it feels more like a 25-watt incandescent if you ask me."
When it comes to halogen lights, they are only as efficient as incandescent lights, so the same efficiency considerations apply here. But since halogen lights are typically much more direct than incandescent bulbs, LED lights that are designed to replace halogen lights are both more efficient than the halogens they replace, and work well for the direct light that halogen bulbs provide. You can find LED replacement bulbs for the most common halogen fixtures such as GU10 and MR13, and this may be a good place to start the switchover.
LED house light designers work around the issue of the narrow beam of a single LED, by building household LED light bulbs that are a collection of individual LEDs, with each diode aimed at a different angle, so that a wider area is highly illuminated. This increases the area of full light coverage of an LED light. However very few such bulbs provide the breadth of area coverage of existing incandescent bulbs or CFLs and at the same time are bright enough.
Where LED lights outshine existing bulbs is as replacements for lighting that is (or should be) highly directed. For example, a light in a narrow hallway, where the chief point of the light is to show people their way down the hall, would be a good application for LEDs.
Task lighting is another example of an application where LEDs shine. Why light up your entire work room if all you need to see is the tools on the work bench right before your eyes? A couple of LED bulbs hanging above the work area will do the trick nicely. But you can only cost-justify this in energy savings if you live half your life in the workroom.
LED light bulbs are, in theory at least, very durable, when compared to incandescent bulbs and compact fluorescent bulbs. LED bulb life ranges from 35,000 to 200,000 hours, compared to 1,000 hours for a good incandescent light, and 8,000 hours for a CFL. But I have seen many consumer ratings of LED bulbs that report burn-out within a few days of being switched on. Clearly there are some quality problems still to be worked on - yet another good reason for holding off a couple of years before switching wholesale to LEDs.
Whether LEDs will really live up to their long lasting billing remains to be seen - even the 35,000 hour ones would need to be on 24x7 for 4 years before they come close to reaching their advertised range. And LED lights do dim with age - so while a bulb might have a lifetime of 35,000 hours, it won't emit its starting light level for the full 35,000 hours - the older it gets, the less light it will emit. LED lights do decline progressively in light intensity and therefore in efficiency, although they will still be more efficient than either CFLs or incandescent bulbs throughout their life.
The "color temperature" of a light bulb, measured in 'degrees Kelvin', determines human visual response to its light. You are probably comfortable with the yellowish glow of incandescents at around 2800 Kelvin (2800K), even though fluorescent lighting is closer to the natural daylight temperature of 6000K. Any LED with a temperature of 6000K or higher will seem bluish, and any LED with a color temperature above 4000K will appear whiter than an incandescent bulb.
While homeowners are typically worried about how fluorescent or LED lights can make their rooms look blinding white instead of the comforting yellow glow provided by incandescent bulbs, you should remember that a little sacrifice in color temperature will put a big dent in your electricity bill. Be a trend-setter, not a trend-follower - start converting your home lighting to true daylight colors, whether with CFL lights or LED light bulbs. You will be helping your family and friends to switch over, when they find out they won't be the only ones with a slightly bluer light hue in their homes.
Whether you switch a few of your lights to LED lights now, or let the technology and reliability improve, you can count on the fact that LEDs will play an increasing role in lighting our houses in the years ahead. I personally think it makes sense to wait, except in certain special lighting situations where the direct, high-color-temperature light of LEDs is what you're after, and where money is no object. If you just want to save money - or to cut your energy use for environmental reasons - an equal amount of money spent on CFLs, or most other energy efficiency upgrades, will cut your energy bills and carbon footprint more than buying the LED lights now available.
About the Author
Robin Green runs Green-Energy-Efficient-Homes.com, a website that helps people find ways to use less energy at home. For more on energy saving LED lights, see LED house lights on Green Energy Efficient Homes.
