Tomotsugu Goto

Tomotsugu Goto

I am an astronomy Professor at the National Tsing Hua University. Our Universe is full of mysteries…dark energy, dark matter, inflation… Come and explore the mysteries of the Universe with me!

Location Taiwan

Activity

  • Actually, I want to know, too. Feedback is appreciated. We will try to improve in the future.

  • Yes!

  • Interesting!

  • @彥興林 Excellent! Please join my TAs next time.

  • For the darkness of the sky, only observable Universe matters.

  • @NovaBrockbank Thank you for following up!

  • @VeeraV Dark matter does not absorb the light. It only has gravity.

  • True!

  • Interesting!

  • @RaB I guess you would love Mauna Kea Observatory. https://www.youtube.com/watch?v=n5fZQkvlHLk

  • Right. For the darkness of the night sky, the observable Universe matters.

  • True!

  • Actually surface brightness does not decrease with the distance. So, the inverse square law cannot explain the darkness.

  • An excellent point!

  • We can explain why now.

  • True!

  • Expanding but finite.

  • A very good discussion! Thank you Julie and Steve!

  • Thank you for a good comment! I will explain in the next video!

  • Excellent!

  • Thanks for good comments! I will explain in the next video.

  • Thanks for a good comment!

  • @DerekCharlton Interesting!

  • @AlexanderBousbaine An excellent point! I am sure there are!

  • Actually surface brightness does not decrease with the distance. I will explain in my next video.

  • Thanks for a good comment! I explain in the next video.

  • Thanks for a good comment! I talked about Betelgeuse here, https://www.youtube.com/watch?v=HGEVbDu_-Lg

  • Actually the surface brightness does not decrease with the distance. I explain in the next video!

  • @TedRook Excellent!

  • @BrianRogers Excellent!

  • An excellent point! Actually, the light from very distant galaxies is redshifted into near-infrared. Another reason the sky is dark in optical.

  • Excellent!

  • Actually surface brightness does not decrease with the distance. Please watch my next video.

  • A very good comment! Actually surface brightness does not decrease with the distance. I explain in the next video.

  • Excellent!

  • I explained in the next video!

  • An amazing insight by Poe!

  • Yes, that is part of the reason.

  • Excellent! The age of the Universe is finite.

  • All correct!

  • A good point. I did not mention, but could we think outside of the atmosphere in space? The question is still valid.

  • hahaha, this is a great one! Actually the surface brightness does not decrease with the distance.

  • Actually the surface brightness does not decrease with the distance.

  • A good point! Actually, the light from very distant galaxies is redshifted into near-infrared. Another reason the sky is dark in optical.

  • Dark matter does not emit the light, but also does not absorb the light. More on dark matter coming up in the next chapter!

  • An interesting analogy! In this case, the Universe is full of stars, but the size of the garden is limited (and thus limited amount of stars).

  • I hope we can increase the percentage!

  • Thank you!

  • Thanks for the encouragement frmo anthoer dust!

  • Galaxies are much more luminous than planets, so we can observe them at much more distant Universe.

  • Thank you! An interesting point!

  • Human eyes can only see the light in visible wavelengths, but CCD cameras and other detectors can detect signals in other wavelengths such as X-ray, radio... Computers can convert signals into images in the visible wavelengths, so we can see with our eyes.

  • Some astronomers use sizes of structures to measure the expansion. For example, https://en.wikipedia.org/wiki/Baryon_acoustic_oscillations

  • We actually use pasec for research. It is friendrier to observations. https://en.wikipedia.org/wiki/Parsec

  • A good point! We all have. For example, we do not know where all hydrogens are. This is called the missing baryon problem. https://en.wikipedia.org/wiki/Missing_baryon_problem

  • A very good question. The space is not expanding into anything. Space itself is expanding. This article might interest you. https://www.discovery.com/science/Universe-Is-Expanding

  • Thank you! We are explorers.

  • Let's get started!

  • Thanks!