Is the Expansion of the Universe Accelerating Beyond the Speed of Light?

In summary: One is called the "big rip" and it's where the universe suddenly and dramatically expands and pulls everything apart. Another is where the universe continues to grow but eventually reaches a point where the expansion exceeds the speed of light, at which point we would essentially be looking at an empty universe. Neither of these are very likely.
  • #1
MostlyHarmless
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As I understand it, the rate at which the universe is expanding is increasing. Can the rate of expansion ever exceed the speed of light? If/when it does exceed the speed of light, Does that mean that we would look up into the night sky and see nothing? Does that mean that it is taking longer and longer for light to reach us from distant galaxies? What other implications does this have?
 
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  • #2
Jesse H. said:
As I understand it, the rate at which the universe is expanding is increasing. Can the rate of expansion ever exceed the speed of light? If/when it does exceed the speed of light, Does that mean that we would look up into the night sky and see nothing? Does that mean that it is taking longer and longer for light to reach us from distant galaxies? What other implications does this have?

It is already far in excess of the speed of light. This is a recession velocity however, so nothing is MOVING at FTL, it's just receeding at FTL. Currently the objects at the edge of our observable universe are receeding at about 3c.

Eventually, according to current theory, the local cluster, and perhaps only the Milky Way, will eventually be all that is left in our own observable universe. That means that from Earth you would see almost exactly what you seen now with the naked eye, but with telescopes it would be a different story.

If the "big rip" scenario (unlikely) happens, then EVERYTHING will spread apart.
 
  • #3
Total dark energy energy is increasing, since it is proportional to the volume of the universe. Another way of putting it is the dark energy density is constant, so that locally it doesn't get any stronger. This means that things held together (such as galaxies and galactic clusters) by gravity will stay together.

http://en.wikipedia.org/wiki/Dark_energy

See section on "Implications". There are alternate scenarios to the description I gave.
 

1. What is the expansion of the universe?

The expansion of the universe refers to the continuous increase in the distance between objects in the universe. This phenomenon was first observed by Edwin Hubble in the 1920s and has been confirmed by numerous experiments and observations since then.

2. How is the expansion of the universe measured?

The expansion of the universe is measured by observing the redshift of light from distant objects. This redshift is caused by the stretching of light waves as they travel through the expanding universe. The larger the redshift, the faster the object is moving away from us and the greater the expansion rate.

3. What is dark energy and how does it relate to the expansion of the universe?

Dark energy is a mysterious force that is thought to be responsible for the acceleration of the expansion of the universe. It is believed to make up about 68% of the total energy in the universe and its presence is inferred from observations of the universe's expansion rate.

4. Will the expansion of the universe ever stop?

Based on current observations and theories, it is believed that the expansion of the universe will continue indefinitely. However, the rate of expansion may change over time depending on the amount of dark energy present in the universe.

5. How does the expansion of the universe impact our understanding of the Big Bang theory?

The expansion of the universe is a key piece of evidence that supports the Big Bang theory, which states that the universe began as a single point and has been expanding ever since. The expansion of the universe also helps explain the distribution of matter and the cosmic microwave background radiation observed in the universe.

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