rordes

Latest Posts by rordes

Libraria

Better late than never!

Here’s a comic about our favorite icy moon, Enceladus!

http://www.space.com/20543-enceladus-saturn-s-tiny-shiny-moon.html

Source Ethan Bortnick

Starry Greetings!

Let’s start hot objects month with our infamous red hypergiant: VY CANIS MAJORIS!

https://www.universetoday.com/39472/vy-canis-majoris/

http://astrobob.areavoices.com/2012/01/28/the-biggest-star-in-the-sky-and-how-to-see-it/

https://www.universetoday.com/13507/what-is-the-biggest-star-in-the-universe/

https://www.space.com/31209-hypergiant-star-vy-canis-major-weight-loss.html

Happy Sunday everyone! 

Here’s a comic on a ticking time bomb!

This week’s entry: “Betelgeuse”

http://www.space.com/22009-betelgeuse.html

On the classification of hidden variable models

Since I already posted several entries about Bohmian Mechanics, it's time to have a look on the classification of hidden variable theories in general. Though in the following we adopt the dogma of the wave function being a representative of physical reality (which can be denied of course), I hope you will get a more differentiated impression of possible approaches to quantum theory. The classification presented was developed by Nicholas Harrigan and Robert Spekkens [1]. Here we will reduce ourselfes to a simplified and non-mathematical overview.

What are the models of interest?

The categorization concerns ontological models. This means we assume that there is an ontic state of the physical system, denoted by λ, which describes the physical properties of the system (remember, this is a huge assumption that can be neglected completely in other approaches of quantum theory.) Then, a measurement reveals something about the ontic state (remember, the measurement does not create new facts in this view) which existed prior to the measurement. Our task is to find out how the ontic state λ is related to the wave function ψ in a given model. It's important to remark that any ontological model needs to reproduce the empirical results of textbook quantum theory - the Born rule. p=|ψ|^2

ψ-complete, ψ-supplemented and ψ-epistemic

The first class, the ψ-complete models are the most straightforward: Here we have a one-to-one-relation between the ontic state λ and the wave function ψ. A complete description of reality is provided by the wave function - that's it. Figure A shows the one dimensional ontic state space represented by ψ . A line which is basically the same as λ.

ψ-supplemented models have additional structure that completes the wave function. This structure can be regarded as the well-known 'hidden variable' since you cannot measure their values in an experimental setup. Figure B shows the ontic state space of such a model: The ontic state is not only provided by ψ, but also by the hidden variable ω. The ontic state space has therefore an additional dimension.

A ψ-epistemic model reduces the wave function ψ to be of epistemic character - it is not an element of the ontic state space (therefore the loop outside the one-dimensional state space denoted by λ in figure C).

Given these classes you can define two dichotomic classifications: ψ-complete v.s. ψ-incomplete and ψ-ontic v.s. ψ-epistemic. Those properties and the three classes are summarized in the following figure (Ask yourself, why there is no model that is ψ-complete and ψ-epistemic simultaneously!)

To which class does Bohmian Mechanics belong?

The ontology of Bohmian Mechanics is clear: The wave function ψ is part of the physical reality, though a complete description can only be achieved with additional variables: the positions of point particles. Therefore Bohmian mechanics falls in the class of ψ-supplemented ontological models.

Finally it's crucial to mention what all of these models have in common: their ontic character requires the acceptance of non-locality. A result which is of such fundamental character that it is not tolerated by the entirety of the physics community - therefore you can also find a lot of attempts of restoring locality in non-ontic-models. More on this will follow in the future.

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[1] Einstein, incompleteness, and the epistemic view of quantum states - Harrigan, Spekkens

😘

I send out bdsm vids here ;)

The solar eclipse that occurred in Chile on July 2, 2019 photographed by Dan Marker-Moore. Great job!

Via Colossal

The Aesthetic Beauty of Math

The best mathematics, like the best literature, will continue to cause intense emotional satisfaction to thousands of people after thousands of years.

André Weil and G. H. Hardy views on mathematical beauty.

A mathematician, like a painter or a poet, is a maker of patterns,” he wrote. “If his patterns are more permanent than theirs, it is because they are made with ideas.” Hardy went on to characterize what makes a mathematical idea worthy: a certain generality, a certain depth, unexpectedness combined with inevitability and economy.

See Hardy’s essay A Mathematician’s Apology (wiki, PDF, Amazon)

😂

Russian troops stock up on supplies for oncoming winter offensive (1941)

This is a Chinese and Japanese Lantern plant. It blooms in the winter and dries up in the spring, revealing the bright red fruit that lives inside its arid petals.

Jesus breakdancing to impress his friends (AD 20)

😂😂😂

Earth and Moon from Saturn [1024x1024]

source

An array of photosynthetic plankton collected from the California coast by a colleague (thanks Greg!) 

The first two are diatoms- an unknown species and Biddulphia (mobilienisis?). I’m not too certain what those last two are, but that’s the beauty of microscopy. No matter how much you’ve seen, you’ll eventually find something completely new! 

…no but seriously if anyone can help me identify those that would be great :D

The various spines and needles help keep the plankton buoyant and may possibly deter grazing from other plankton looking for a meal. I say may because some copepods actually prefer spiny diatoms over spine-less variants of the same species. To the copepod, the spines make the diatom seem bigger and thus more appealing as food (source). I guess that makes these diatoms the equivalent of bags of chips filled with mostly air.

Spatial resolution of Hi-C compared to that of SDO/AIA

The highest resolution data from the corona we currently get on a regular basis are from the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO), however, even higher resolution images have been obtained during a sounding rocket flight by the High-resolution Coronal Imager (Hi-C). The scientific objectives of Hi-C are central to the goal of understanding the Sun’s activity and its effects on the terrestrial environment by providing unprecedented views of small-scale structures in the solar atmosphere.

The Hi-C instrument is scheduled to launch on a sounding rocket May 29, 2018. This will be the third launch of the Hi-C instrument.

Image credit: MSFC/NASA

*blink* 😽 | sukiicat

Staring Down Hurricane Florence via NASA https://ift.tt/2OeQkiW

Active Prominences on a Quiet Sun (Photo: Alan Friedman) [OS] [821x1152]