Meta & Fysikken: Afsnit 44: Beboelige planeter, Grønlandsk krater, fremtidsudsigter mv.

Vi snakker om lidt forskellige aktuelle emner.

1: Hvor langt væk er den nærmeste beboelige planet?
300000 planeter i habit zone i MW. (Mælkevejen)
MW: 52 000 lysår i radius og 1000 lysår tyk. Areal af cirkel: pi * r^2 = 8.494.866.535 lysår^2
Volumen af MW: 1000 lysår * Arealet= 8.494.866.535.306 lysår^3
Hvor mange 'beboelige' planeter er det så per rum enhed?
300 000 planeter / 8.490.560.000.000 lysår^3 = 0.0000000353 planeter / lysår^3
Hvor stor en kugle for at have 2 stk? (vores og en fremmed beboelig planet).
2 planeter / 0.0000000353 planeter / lysår^3 = 56 603 733 lysår^3
Hvor langt væk er det?
3 root of that is: 384 lysår som er afstanden mellem 2 planeter, hvis altså de er jævnt fordelt.

December 12, 1901 - Første radio signal. Jorden første radiosignal er blot nået 119 lysår ud på nuværende tidspunkt!

2: Fremtiden: Kunne man før i tiden bedre forestille sig fremtiden?

Var fremtiden før lys, hvor nu den er dyster? Hvad er der af positive fremtids scenarier?

3: Kina på månen:

https://www.nytimes.com/2020/11/23/science/china-moon-rocks.html

China launched a spacecraft to the moon’s surface on Monday, aiming to be the first nation to bring back lunar rock and soil samples in more than four decades.

The mission, called Chang’e-5, is the latest step in an ambitious space program that China hopes will culminate with an international lunar research station and ultimately a human colony on the moon by the 2030s.

The entire Chang’e-5 mission, from liftoff to the recovery of the rock samples, will be over in less than a month.

The landing site is a volcanic plain called Mons Rümker in the Oceanus Procellarum region on the moon’s near side. For planetary scientists, rocks collected from this region promise a glimpse of a much younger part of the moon. The places explored by Apollo and Luna were all more than three billion years old. Mons Rümker is estimated to be around 1.2 billion years old.

4: Krater under Grønlands is:

12,800 years ago, during the Pleistocene, Earth was warming up from its last Ice Age. Temperatures slowly rose while glaciers retreated, that is, until something major happened that triggered a cold snap big enough to leave its mark on the geologic record. Over the course of just decades – the blink of an eye in geological timescales – the planet cooled somewhere between 3 and 11 degrees Fahrenheit (2 to 6 degrees Celsius). The resulting period is known as the Younger Dryas, a mysterious 1000-year blip in history.

The work, led by Kurt Kjær, professor at the Natural History Museum of Denmark and University of Copenhagen, describes a previously overlooked, 19-mile-wide crater that’s been hiding in plain sight in northwest Greenland’s Hiawatha Glacier. In fact, it’s only about 150 miles from Thule Air Base.

You can see about a third of the crater’s rounded outline on Google Earth.

It is too early to link this crater to the Younger Dryas. Need to date it. Sample through lots of ice 3000 feet = 914m

https://astronomy.com/news/2018/11/massive-impact-crater-beneath-greenland-could-explain-ice-age-climate-swing?utm_source=asyfb&utm_medium=social&utm_campaign=asyfb&fbclid=IwAR024Fq59hy8w6fQ74Cjs5TcxosofClezVwrDXN0REnMcjTtSgeVPpEQ3Pk

5: Purpose of sleep:

https://newsroom.ucla.edu/releases/ucla-scientists-discover-why-we-need-sleep

Scientists calculated that 50% of sleep is REM sleep for babies. When we reach the age of 10, this percentage has been reduced to 25%. At the age of 50, only 15% of our sleep is REM sleep. According to senior author Gina Poe, professor of integrative biology and physiology, sleep is just as essential as food; it is miraculous how well sleep matches the needs of our nervous system. From jellyfish to birds to whales, everyone sleeps. While we sleep, our brains are not resting.

A possible explanation for the previously mentioned reduction in REM sleep is that, as we get older, the purpose of REM sleep shifts from constructing an infrastructure of neural connections to repair and maintenance where minor damage that we sustain during the day gets repaired, and harmful chemicals are removed.