Dark Energy Levels Not Too Constrained For Star Formation

I've always had a bit of a problem with the anthropic scenario of our universe, i.e. the idea that we are living in a universe JUST fined-tuned to allow us to exist. My problem isn't with the observations so far, but rather how much people are already thinking that this must be true, the data are set, and that we can run away with it. Certainly many people outside of cosmology have tried to spin this into whatever directions that they want.

So when news like this comes along, I just want to yell "I told you so!". It is not that I agree or disagree with the conclusion, but it is to point out that in our attempt to understand all of this, our knowledge is still in its infancy, and that we really don't know enough yet to be able to say things one way or the other on many of the big issues. We do have a fuzzy idea on what direction it is going, but in a number of things and observations, more is required to understand things even better.

The new studies ran the simulation on the star formation of our universe against the amount of dark energy in our universe. They can, to put it crudely, dial in various level of dark energy in their simulations. They found that there is a wider range than initially expected for our present universe to form, i.e. it is not in a very narrow range that was thought of. So keeping everything relatively the same, we could see this present universe that we're in for a large range of dark energy.

The simulations allowed the researchers to adjust the amount of dark energy in the universe and watch what happened.

The results were a surprise. The research revealed that the amount of dark energy could be increased a couple of hundred times – or reduced equally drastically – without substantially affecting anything else.

So for dark energy, the parameter is not as "fine tuned" as one expected.

Zz.

https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/sty846/4963750?redirectedFrom=fulltext

https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/sty879/4966995?redirectedFrom=fulltext

Secrets Of The Dark Universe: Simulating The Sky

I'll post the synopsis to this video, which you can also read on YouTube:

An astonishing 99.6% of our Universe is dark. Observations indicate that the Universe consists of 70% of a mysterious dark energy and 25% of a yet-unidentified dark matter component, and only 0.4% of the remaining ordinary matter is visible.

Understanding the physics of this dark sector is the foremost challenge in cosmology today. Sophisticated simulations of the evolution of the Universe play a crucial task in this endeavor.

This movie shows an intermediate stage in a large simulation of the distribution of matter in the Universe, the so-called cosmic web, accounting for the influence of dark energy. The simulation is evolving 1.1 trillion particles. The movie shows a snapshot of the Universe when it was 1.6 billion years old.

While this video may be obvious to people in the field, it would be nice if they had some narration to accompany each scene so that we know what we are looking at! After all, they went to all this trouble to make a visual representation of the simulation and posting it on YouTube for the public to see. Might as well put a little bit more effort in telling us what each of those different scenes are. Otherwise, all we see are cool images without learning anything much.

Of course, the physicist in me would like to know what kind of parameters were used, what are the assumptions, where was this/will this be published, etc. Y'know, the mundane stuff! :)

Zz.

ATLAS On A Smartphone

If you have an Android device (smartphone, tablets), then LHsee app from the Android Marketplace might be something you want to look at.

LHsee is an educational tool available for Android OS mobile smartphones and tablet PCs. It has been custom  designed to provide an accurate and interactive visual representation of complex high-energy physics events recorded by the ATLAS detector. Features include live streaming and reconstruction of collision data from the CERN Large Hadron Collider.

It's interesting that they only released this on the Android platform ONLY and not on iOS, considering that a lot of people that I know of who work at ATLAS use Apple devices.

You can get a more comprehensive description of this app and what it can do by downloading this paper, which you can get for free.

Zz.

Neutron Stars: Billions of Times Stronger Than Steel

A new computer simulation on the core of neutron stars has revealed that it is extremely dense and 10 billion times stronger that the toughest steel that we know of. But that is more fascinating is how it relates to my previous blog entry of "gravity waves". It appears that imperfections, such as mountains, on the surface of the neutron stars can actually generate gravitational (gravity?) waves.

That incredible strength also means that when neutron stars form they can tolerate some imperfections on their surfaces. In this case, such imperfections can be mountain-sized bumps as heavy as Earth. As those bumps ride the fast-spinning stars, their mass disturbs spacetime enough to generate gravity waves, the simulations by Horowitz and Kadau show. First predicted by Albert Einstein, the waves are disruptions that radiate through the very fabric of spacetime. They travel as fast as light and can stretch every atom they encounter. Scientists have deployed new instruments in recent years in an attempt to observe the waves, but so far they have remained elusive.

Humm... gravity or gravitational? :)

Zz.

LHC Project Simulator

OK, I had way too much fun playing with this thing.

Even though the LHC is going to be down till after the scheduled winter shutdown, doesn't mean we all can't pretend that it is running and already producing collisions. In fact, WE can actually simulate a run and start hunting for those elusive particles after all!

This is a LHC project simulator. It tries to simulate the possible outcome of a collision based on the beam/magnet parameters that one start with. It's a lot of fun in a cartoonish sort of way. If only the actual thing is this easy. :)

Zz.