Pondering the universe

Regarding yesterdays congratulation of Henrietta Swan Leavitt (on her namesday). The story about Henrietta Swan Lewitt, is The Untold Story of the Woman Who Discovered How to Measure the Universe. The asteroid 5383 Leavitt and the Leavitt crater on the Moon are named in her honour. If she hadn’t died rather early she might have been nominated for the Nobel Prize. During her career, Leavitt discovered more than 2,400 variable stars, about half of the known total in her day.

At the age of 25 where she worked on the accurate measurements of the brightness of stars. Leavitt’s work with variable stars led to her most important contribution to the field, the discovery of the period-luminosity relation of Cepheid variable stars.

Cepheid variables are stars that go through cycles of brightness and darkness. Henrietta found that when observing a cepheid variable in another galaxy, she could relate the length of the brightness cycle to the size of the star. With this discovery, she was able to determine the distances between stars and the Earth.

“It is worthy of notice”, she observed, that “the brighter variables have the longer periods.” Cepheids are stars that fade and brighten in a regular fashion. Leavitt discovered a direct correlation between the time it took a star to go from bright to dim to how bright it actually was. Knowing this relationship helped other astronomers, such as Edwin Hubble, to make their own groundbreaking discoveries.

Cepheid variables are referred to as “astronomical yardsticks” as they make it easier to measure distances within the universe. Her findings made it possible to measure the whole universe…

And speaking about the universe. Two days ago we talked about this new theory about the pulsating universe (in swedish).


Astronomers today think that the Big Bang has happened before, and both will and has happened again and again and again… They think the universe is pulsating and that the Big Bang is followed by a Big Crunch (when everything falls back together again). The Big Crunch has given ideas about what will happen then. Will time itself reverse? Will everything that has happened before, happen again, just in the other direction? In that case perhaps we will came back to life with full memory… Weird notion.

One also have to think if it (Big Bang) will happen again. Will everything happen again as well? Will everything repeat itself? Perhaps that’s what we call “Deja Vu”? Or will the next Big Bang bring a totally different universe? If time is plastic, perhaps this is the thing we talk about when we talk about parallell universes? It’s almost as “this time” only slightly modified… And perhaps the more Big Bangs in between, the more different the universes are… Or will this pulsating universe fit together with the multiversum theory?

Stay tuned, we’ll try to find out.

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