[ogig]

But, can we really replicate sunlight? Might sound pessimist but the sun is a star, 1AU away, with a huge mass compared to earth, and It's the energy source for life here. Seems like a very long shot aspiring to create an artificial replacement for that, even for the narrow objective of tricking our bodys.

There must be some scientific knowdlegde regarding this that I ignore.

[contravariant]

Like you said, the sun is 1 AU away, we're getting a fraction of its energy. Actually that fraction is still way beyond what were able to generate, and will remain that way for quite some time. However, we only need to illuminate the part of the earth with humans in it, which is a more manageable scale.

What we consider sunlight is essentially the light emitted by any object at 6000K, which is reasonably easy to achieve but somewhat difficult to contain. And actually mimicking the sun is usually not the best method (for one, the unfiltered UV would be very unhealthy). It's possible to approximate the visible part of that light though, and we're gradually getting better at it.