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Context This question explores the fundamental differences between light propagation in a vacuum like space and within an atmosphere like Earth's. It delves into concepts of light absorption, scattering, and the factors that limit the distance light can travel. Simple Answer Light travels really far in space because there isn't much stuff to block it. On Earth, air and particles scatter light, making it fade. Space is mostly empty, so light keeps going. However, light can still be absorbed by things like dust or gas clouds, though these are rare. Also, the light's energy spreads out as it travels, becoming weaker over vast distances. Detailed Answer In the vast emptiness of space, the behavior of light differs significantly from what we experience on Earth. Our planet's atmosphere is a bustling environment filled with gas molecules, dust particles, and other forms of matter. When light, such as that emitted from a flashlight, travels through this atmosphere, it interact...

Context The question explores the evidence and observations that support the theory of the expanding universe, addressing whether it's a confirmed fact or a probable theory. Simple Answer Everything far away looks like it's moving away from us. The farther something is, the faster it seems to be moving away. This 'moving away' is due to space itself stretching, not things physically moving through space. Scientists measure this by looking at the light from distant objects and seeing it stretched (redshifted). These observations match predictions from Einstein's theory of general relativity, which describes how gravity works. Detailed Answer The primary evidence for the expansion of space comes from the observation of redshift in the light emitted by distant galaxies. Redshift is the phenomenon where the wavelengths of light are stretched, causing the light to appear redder. This is analogous to the Doppler effect, where the frequency of a sound wave changes dependin...

Context This question explores the relationship between redshift, wavelength, and energy of light in the context of an expanding universe. It asks whether light loses energy as its wavelength increases due to redshift and, if so, where the lost energy goes. Simple Answer Imagine a wave in the ocean. As the wave travels, it gets stretched out, making its peaks farther apart. This is similar to redshift. The stretched out wave has less energy. Light behaves like a wave, and its energy is related to how tightly packed its waves are. The closer the waves, the higher the energy. When the universe expands, light traveling through it gets stretched, just like the ocean wave. This stretching makes the light's waves less tightly packed. So, yes, the light loses energy as it redshifts, but it's not really lost. It's just spread out over a larger area. The energy doesn't disappear; it's transferred to the expanding universe itself. Detailed Answer The phenomenon of redshift, ...