How Far Is That Galaxy Really? Exploring the Expansion of Space

TLDRGalaxies that are billions of light years away can be much further due to the expansion of space. Objects moving faster than the speed of light make their light reach us eventually. The universe is not stagnant; it is constantly expanding.

Key insights

🌌Galaxies can be further away than their light travel time due to the expansion of space.

🔭Light from distant galaxies can still reach us, even if the galaxies themselves are moving away from us faster than the speed of light.

🌠The observable universe is expanding, and we can only see a fraction of the entire universe.

🧲Space itself can expand, moving galaxies further apart from each other.

🔢The expansion of space affects the distance between objects and the time it takes for their light to reach us.

Q&A

How can galaxies be further away than their light travel time?

—The expansion of space stretches the distance between objects, making them move apart faster than light can travel.

Can light from a galaxy still reach us if the galaxy is moving faster than the speed of light?

—Yes, because the light was emitted when the galaxy was closer to us. As long as the light eventually gets inside our 'Hubble sphere', we can see it.

How big is the observable universe?

—The observable universe is constantly growing, but we can only see a fraction of the entire universe. The 'Hubble sphere' marks the boundary of what is currently observable.

Does the space between objects also expand?

—Yes, space itself can expand, carrying galaxies apart from each other. This expansion affects the distances between objects and the time it takes for light to travel.

How does the expansion of space affect the universe?

—The expansion of space affects the size and distribution of galaxies, as well as the overall structure and evolution of the universe.

Timestamped Summary

00:00Imagine a galaxy that is billions of light years away. But due to the expansion of space, it can be much further than that.

02:57Light from distant galaxies can still reach us, even if the galaxies themselves are moving away from us faster than the speed of light.

06:04The observable universe is expanding, and we can only see a fraction of the entire universe.

08:56Space itself can expand, moving galaxies further apart from each other.

10:43The expansion of space affects the distance between objects and the time it takes for their light to reach us.

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