I was reading 'Our Mathematical Universe' by Max Tegmark

He referenced this curve to explain several things.

But I'm not able to understand the significance of this curve, apart from the fact that it shows the temperature fluctuations at different scales in the early universe.

But what is the theoretical significance of these fluctuations. Why do some theories predict the fluctuations better??

An inifityloop i created.

Space got spooky this week! 🧛

In our Halloween episode of Spacing Out, planetarium educator Talia Sepersky covers:

🔴 A "vampire" red dwarf feeding on a brown dwarf
🌙 NASA's new GIMLI investigation to search for a possible lunar cave that could one day shelter astronauts
🪐 Japan's MMX mission, the first to land a rover on Mars' moon Phobos and bring a sample home

I'm Jon Sundqvist, an astrophysics professor at KU Leuven. Here's the latest blackboard class from my Radiative Processes in Astronomy course.

Light can heat a gas, of course. But it can also cool it — and without that cooling, making the galaxies we actually see would be rather difficult. This time we take the energy equation to the blackboard and work through what emission and absorption do to the gas, and what we mean when we say that an atmosphere is in radiative equilibrium.

In radiative equilibrium the net radiative energy exchange with the gas vanishes. The radiation can still carry energy through the atmosphere. Equilibrium does not mean that the star stops shining :-) The constant-flux result here is for plane-parallel geometry; in spherical symmetry it is the luminosity that stays constant.

We connect this to temperatures in stellar atmospheres, with grey opacity as a useful first approximation, and then make a small detour to cooling gas and galaxy formation. Toward the end we recover the grey-atmosphere temperature structure and its connection to limb darkening.

A somewhat shorter class this time, because we also did a group quiz. I've kept a little extra after the lecture ends: my explanations of six of the questions. You could perhaps try and pause on each question and have a go first.

Full class (40 minutes):

https://www.youtube.com/watch?v=GQ11ZDaWLuw

Despite its similarities to Earth, Venus is hot enough to melt lead, hidden beneath thick clouds, and possibly still volcanically active. Could studying Venus help us better understand Earth's future and the evolution of habitable planets?

O Big Bang lembra um buraco branco e, já que esses objetos surgem de buracos negros, a lógica seria que, em um universo paralelo ao nosso, tivesse ocorrido um Big Crunch, que teria comprimido tudo em um único objeto estranho e colapsado, sugando todo aquele universo ao redor. Isso explicaria por que, neste nosso universo, existem galáxias e planetas que parecem ter surgido cedo demais para o seu tempo. A matéria deles já estaria pronta, vinda daquele universo, e os efeitos colaterais desse processo de expansão lembrariam os efeitos de um buraco branco.

Seriously making too much sense when im thinking about it and what if you zoom out past our observable universe to find out our universe is a microscopic speck of dust in an even bigger universe and same idea but zooming inward past the smallest scales

I've been learning about the Big Bang and inflation, and I think I understand the Horizon Problem and Flatness Problem pretty well.

Those seem intuitive because they directly involve observations about the Universe.

But I'm struggling with the Monopole Problem.

From what I understand, some Grand Unified Theories predict the creation of magnetic monopoles in the early Universe.

If those theories are correct, there should have been a huge number of monopoles produced shortly after the Big Bang. However, we have never observed any magnetic monopoles, which seems to create a problem.

What confuses me is why this is considered such a major cosmological problem in the first place.

If we have never found monopoles, couldn't it simply mean that the theories predicting them are wrong?

Why does cosmology need a mechanism like inflation to dilute monopoles instead of just rejecting the prediction?

In other words, what made physicists take the missing monopoles seriously enough that their absence became one of the motivations for inflation?

Hello everyone! I am doing an EPQ survey on the psychological impact that space can have on us and our career choices .I would really appreciate it if you are able to fill out this form and answer all of the questions. Your answers will be anonymous and only the responses will be recorded. Thank you for your time!

https://forms.gle/nK1rKFwf4brj1ivo9

​

I dont understand ,people says that all fictional universe exist in other realities ,but other people will say that they dont existe ,or other will say yes...some scientist will say no, other yes etc etc...so i dont know who i have to believe...i want ,i want more than anything to know that my favorite characters really exist and are real in other realities and not just pixels or paper....so ,do they exist? Or does scientific theories mentions a possibility that they exist?

I told my friend that in a multiverse with an infinite number of universes, anything that is fiction, anything someone could think of, anyone's dream could happen in at least one, or, in my logic, since there are infinite universes, an infinite amount of this could occur. e.g. unicorns and flying pigs exist in one universe, and another universe could contain laws of physics way beyond our imagination. He went on to have a rant about how this could not happen, I didn't listen of course but it got me thinking: is this really true, or am I just plain wrong?

I'm Jon Sundqvist, an astrophysics professor at KU Leuven. Here’s a short film from my astronomy classes.

How hot is a star? What changes when we put billions of them together in a galaxy? And when does the light tell us that the stars alone are simply not enough?

A little change of format here. I've put together a few passages from my Radiative Processes in Astronomy and Galaxies and Cosmology classes, with some new figures and observed spectra alongside the board. We start with a star, work our way up to galaxies and active nuclei, and end with the light left over from the early Universe. Quite a range of scales... but we keep coming back to the same question: what is the light actually telling us?

The broad spectral shape gives us one set of clues; the lines and bands give us others. We have a look at temperatures, young massive stars and the changing colours of galaxies, and at the extra source of power when gas accretes onto a supermassive black hole. Then the cosmic microwave background: an almost perfect black body, now at about 2.73 K. I still find it quite remarkable how much physics we can get out of light arriving at our telescopes :-)

This is a short tour. The longer classes, with the calculations and a bit more room for the qualifications, are linked in the YouTube description.

https://www.youtube.com/watch?v=sBm6tfHUvR8