This is Why Physics Can't Totally Explain the Universe's Expansion

We know that the universe is expanding but we can't really seem to agree on how fast.

We know that the universe is expanding but we can't really explain how or agree on how fast. That's what the good people at SciShow Space explain in this video.

Astronomers have gotten pretty good at calculating how fast this expansion is happening. There are two main methods for measuring this: observing astrophysical objects or using the laws of physics to extrapolate.

But those methods don't agree. And according to a new study that might not be a mistake: the numbers might actually be different.

One of the ways of calculating this expansion is calculating the distances to stars called a cepheid. In a new study, researchers looked at 70 cepheids from a nearby dwarf galaxy.

They found that the universe was expanding at a rate of 74.3 km/s/Mpc. The number is in line with other previous finds.

However, it does conflict with other measurements. One conflict is from the cosmic microwave background (CMB) study.

This is the oldest light in the universe that humanity will ever see. It has helped discover how fast the universe was expanding 13 billion year ago.

They have also used the rates to extrapolate how fast the universe is expanding now and the result is different from the cepheid-based data. Now, we have a conundrum but we will let SciShow Space explain this problem. 

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