The Size of the Universe: How Much Can We See?

TLDRThe size of the observable universe is constantly expanding, but there are limits to our ability to see and explore it. The cosmic microwave background (CMB) represents the farthest light we can see, emitted 13.7 billion years ago. The particle horizon, which encompasses our view of the universe, continuously expands but has a finite limit. As the universe accelerates, the Hubble horizon will eventually collapse, limiting our view. The cosmological event horizon marks the point beyond which no signal can ever be received. In about 10 billion years, our view of the universe will be at its broadest, but over time, the light that reaches us will be increasingly redshifted. Eventually, the sky will go dark.

Key insights

🔭The observable universe is constantly expanding, with the cosmic microwave background representing the farthest light we can see.

🌌The particle horizon encompasses our view of the universe and continuously expands, but it has a finite limit.

🌀The Hubble horizon, which marks the furthest distance we can see due to the expansion of the universe, will eventually collapse.

⚫️The cosmological event horizon is the boundary beyond which no signal can ever be received, regardless of how long we wait.

🌌In about 10 billion years, our view of the universe will be at its broadest, but the light that reaches us will be increasingly redshifted.

Q&A

What is the cosmic microwave background (CMB)?

—The CMB is the farthest light we can currently see, emitted from the hot hydrogen plasma around 300,000 years after the Big Bang.

What is the particle horizon?

—The particle horizon encompasses our view of the universe and continuously expands as the universe expands.

What is the Hubble horizon?

—The Hubble horizon marks the furthest distance we can see due to the expansion of the universe. It will eventually collapse.

What is the cosmological event horizon?

—The cosmological event horizon is the boundary beyond which no signal can ever be received, regardless of how long we wait.

Will our view of the universe ever go dark?

—Over time, the light that reaches us from the expanding universe will be increasingly redshifted, and eventually, the sky will go dark.

Timestamped Summary

00:00The observable universe is constantly expanding, with the cosmic microwave background (CMB) representing the farthest light we can see, emitted 13.7 billion years ago.

04:25The particle horizon encompasses our view of the universe and continuously expands, but it has a finite limit.

09:29The Hubble horizon, which marks the furthest distance we can see due to the expansion of the universe, will eventually collapse.

13:29The cosmological event horizon is the boundary beyond which no signal can ever be received, regardless of how long we wait.

15:06In about 10 billion years, our view of the universe will be at its broadest, but the light that reaches us will be increasingly redshifted.

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