At last after reading some of the new posts i dont feel like iam alone on this one. I was a bit upset by some of the eariler comments. I see many mixed views on this subject and a very strong sense of knowing from each individual. But iam not going to repeat myself on the matter anymore to the peeps who dont understand or just dont want to understand!! If you dont believe it look it up, and when you look it up and if you still cant understand it, then ask someone to explain it to you, whom you do believe. Then if you still dont want to believe it, you can continue using 12x24 watt cfls to grow your 2-4 plants, when in reality a single 250 watt cfl will do a much better job. Peace, love , and happiness to you all and over grow the world with the beautiful herb. :).[/QUOTE
You have taken a fact, removed it from the moorings of context, and set it adrift in a sea of speculation. You have just said in an exceptionally convoluted way what we already knew. One 1000w has more INTENSITY than 2 500w. However, what you fail to take into account is the inverse square law. It is the magical formula that explains why 2 500w have their place over 1000w sometimes.
This is a breakdown of how the inverse square law works, courtesy of the wikipedia article:
"
Light and other electromagnetic radiation
The
intensity (or
illuminance or
irradiance) of
light or other linear waves radiating from a
point source (energy per unit of area perpendicular to the source) is inversely proportional to the square of the distance from the source; so an object (of the same size) twice as far away, receives only one-quarter the
energy (in the same time period).
More generally, the irradiance,
i.e., the intensity (or
power per unit area in the direction of
propagation), of a
spherical wavefront varies inversely with the square of the distance from the source (assuming there are no losses caused by
absorption or
scattering).
For example, the intensity of radiation from the
Sun is 9126
watts per square meter at the distance of
Mercury (0.387
AU); but only 1367 watts per square meter at the distance of
Earth (1 AU)an approximate threefold increase in distance results in an approximate ninefold decrease in intensity of radiation.
In
photography and
theatrical lighting, the inverse-square law is used to determine the "fall off" or the difference in illumination on a subject as it moves closer to or further from the light source. For quick approximations, it is enough to remember that doubling the distance reduces illumination to one quarter;[SUP]
[4][/SUP] or similarly, to halve the illumination increase the distance by a factor of 1.4 (the square root of 2), and to double illumination, reduce the distance to 0.7 (square root of 1/2). When the illuminant is not a point source, the inverse square rule is often still a useful approximation; when the size of the light source is less than one-fifth of the distance to the subject, the calculation error is less than 1%.[SUP]
[5][/SUP]
The fractional reduction in electromagnetic
fluence (Φ

for indirectly ionizing radiation with increasing distance from a point source can be calculated using the inverse-square law. Since emissions from a point source have radial directions, they intercept at a perpendicular incidence. The area of such a shell is
where
r is the radial distance from the center. The law is particularly important in diagnostic
radiography and
radiotherapy treatment planning, though this proportionality does not hold in practical situations unless source dimensions are much smaller than the distance."
As you can see; after a certain point, it becomes more efficient to use more small lights than one larger one. Light is a particle in motion. Much like all other objects in motion, it is not immune to the laws of entropy. As you move farther away from your source of light, it becomes proportionately less intense per the inverse square law. Which makes sense, given the increasing distance and area covered the farther you get from your source of light. So, it stands to reason that spreading your energy so that it is always at it's optimum intensity via multiple bulbs has it's uses in larger areas.
TLDR:Lumens are visible light at the source. As you get farther from your source, you lose energy to environmental factors (energy required to travel, dispersion of photons into the surrounding environment, etc.). Same reason a 1000 lumen flashlight is alot brighter 2 feet away, than it is across the street. I think mostly that the OP has found a tidbit of knowledge, and didn't think through the whole process before drawing a conclusion. Lumens don't change, because they can't. However, lumens are only part of a much larger ball of wax that you are ignoring.