Cosmic background radiation 2 | Scale of the universe | Cosmology & Astronomy | Khan Academy

TL;DR

As the universe continues to expand, the cosmic background radiation will change and become more red-shifted, eventually reaching a point where it can no longer be observed as electromagnetic radiation.

Transcript

In the last video, we learned that 380,000 years after the Big Bang, which is still roughly 13.7 billion years ago, every point-- I shouldn't say every point-- every atom in space that was kind of at this roughly 3,000 Kelvin temperature was emitting this electromagnetic radiation. Since every point in space was, there were points in space, or ther... Read More

Key Insights

• 😥 Cosmic background radiation originated from every point in space approximately 380,000 years after the Big Bang.
• 🤩 As the universe matured, condensing into stars and structures, the background radiation changed and became less uniform.
• 😪 The future cosmic background radiation will be more red-shifted and have longer wavelengths, making it appear redder.
• 😪 Eventually, the background radiation will be so red-shifted that it will no longer be observable as electromagnetic radiation.

Questions & Answers

Q: What is cosmic background radiation?

Cosmic background radiation is the electromagnetic radiation that pervades throughout the universe and is a remnant of the early hot and dense state after the Big Bang.

Q: How will the cosmic background radiation change in the future?

The background radiation will become more red-shifted and have longer wavelengths as the universe expands. This means it will appear redder and eventually become undetectable as electromagnetic radiation.

Q: Will the cosmic background radiation disappear in a billion years?

While the cosmic background radiation from a particular point in space will no longer be uniform, we will still observe radiation from further out points in space, albeit with more red-shifted and longer wavelengths.

Q: Is there a limit to how far we can observe cosmic background radiation?

Yes, there is a threshold distance beyond which the light and radiation from those points in space will never reach us due to the expansion of the universe. At that point, we won't be able to observe any electromagnetic radiation.

Summary & Key Takeaways

• 380,000 years after the Big Bang, every point in space was emitting electromagnetic radiation at a 3,000 Kelvin temperature.

• As the universe aged, stars and other structures formed, causing the cosmic background radiation to change and become more like the mature universe.

• The universe will continue to expand, and the background radiation will become more red-shifted and have longer wavelengths until it is no longer observable as electromagnetic radiation.