ΕΑΝ ΤΟ ΣΥMΠΑΝ ΔΙΑΣΤΕΛΛΕΤΑΙ ΜΕ ΡΥΘΜΟ ΜΕΓΑΛΥΤΕΡΟ ΤΗΣ ΤΑΧΥΤΗΤΑΣ ΤΟΥ ΦΩΤΟΣ ΠΩΣ ΕΊΝΑΙ ΔΥΝΑΤΟΝ ΝΑ ΠΑΡΑΤΗΡΟΥΜΕ ΟΤΙΔΗΠΟΤΕ ΣΤΟΝ ΕΝΑΣΤΡΟ ΟΥΡΑΝΟ;

 ΕΑΝ ΤΟ ΣΥMΠΑΝ ΔΙΑΣΤΕΛΛΕΤΑΙ ΜΕ ΡΥΘΜΟ ΜΕΓΑΛΥΤΕΡΟ ΤΗΣ ΤΑΧΥΤΗΤΑΣ ΤΟΥ ΦΩΤΟΣ ΠΩΣ ΕΊΝΑΙ ΔΥΝΑΤΟΝ ΝΑ ΠΑΡΑΤΗΡΟΥΜΕ ΟΤΙΔΗΠΟΤΕ ΣΤΟΝ ΕΝΑΣΤΡΟ ΟΥΡΑΝΟ;

ΑΠΟ ΤΟΝ ROBERT FROST (MHXANIKOΣ  ΣΤΗΝ ΝΑSA)

Astrophysicist Adam Reiss won the Nobel prize for determining that the universe is expanding at 74.2 kilometers per second per mega parsec.

That means that for every mega parsec (3261563.7 light years) it increases its expansion rate by 74.2 km/s.

So, using the commonly stated radius of the universe of about 46 billion light years, which is 14103.6 mega parsecs, we can see that the outer edge of the universe would be expanding at 14103.6 x 74.2 km = 1,046,487 km/s.

The speed of light is 3x10^8 m/s. That means at the outer edge, the universe is supposedly expanding at 3.5 times the speed of light.

However, the universe is only 13.75 billion years old. We have no insight to what is happening further than 13.75 billion light years away.

13.75 billion light years is 4215.7 mega parsecs away. At that distance, the expansion rate should be 1.044 times the speed of light.

That means that everything within 13.17 billion light years of the center is expanding at slower than the speed of light. That means about 95.78% of the possible observable universe is expanding slower than the speed of light.

That leaves plenty for us to see when we look to the heavens.

We also may be looking at galaxies that are currently moving away from us at faster than the speed of light, but we are seeing photons they emitted billions of years ago, when they were not moving away from us at faster than the speed of light because they were closer, then.



ΑΝΑΔΗΜΟΣΙΕΥΣΗ ΑΠΟ ΤΟ QUORA 13/6/2017