The concept of the wavelength of light becoming as large as the observable universe is an interesting one, but it's important to clarify a few points.
The observable universe refers to the portion of the universe that we can observe from our vantage point on Earth, limited by the distance that light has had time to travel since the Big Bang, which is estimated to be about 13.8 billion light-years. This observable universe is constantly expanding as space itself expands.
The wavelength of light determines its color or energy. Visible light, for example, has a range of wavelengths between approximately 400 to 700 nanometers. As the universe expands, the wavelengths of light within it also stretch due to the phenomenon known as cosmological redshift. This means that the light from distant objects is shifted towards longer wavelengths, which can be observed as a redshift. However, this is a gradual process that occurs over large distances and time scales.
If we were to imagine a scenario where the wavelength of light became as large as the observable universe, it would imply an extreme stretching of the light wave over an enormous span. In practical terms, such a situation would have profound implications for the nature of light and the structure of the universe as we currently understand it. It would likely require a fundamental reassessment of our understanding of physics, including the properties of light and the nature of space-time.
It's worth noting that the concept of the wavelength of light becoming as large as the observable universe is purely hypothetical and speculative. Our current understanding of physics and cosmology does not suggest such a scenario.