In 1948, Fermi uncovered the origins of Cosmic Ray Acceleration. Today, the concept of Fermi acceleration is foundational in the study of cosmic ray physics. Initially, it was proposed that cosmic rays scattered off moving magnetic clouds. The underlying calculations for this theory are straightforward. Through his analysis, Fermi identified a power law spectrum. The observed power of -2.9 is connected to the mean free path of the scatters, which is determined to be 2 light years — a plausible distance.
Fermi then posed an intriguing question: "Why aren't there any electrons?" He demonstrated that in a typical galactic magnetic field measuring 10 gauss, the energy loss rate due to radiation for electrons with energy more than or equal to 250 MeV exceeds the energy gain rate. However, for protons, this energy threshold is at an astounding 3 x 10²¹ eV. This note was written in December 4, 1948.
A MasterClass on Storytelling
4 year Storytelling Degree in just 5 minutes
You def need this. Kurt Vonnegut is a total legend.
Bookmark and comeback to this again and again.
"Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there-on a mote of dust suspended in a sunbeam.
The Earth is a very small stage in a vast cosmic arena. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot.
Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.
The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.
It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known"
― Carl Sagan
You'd think every computer should be able to divide two numbers, but early microprocessors didn't have division instructions. The Intel 8086 (1978) was one of the first with division. Let's look at how it implemented division and why division is so hard.
Questa mattina mi ha chiamato Elly Schlein per propormi di guidare uno dei Dipartimenti del Partito Democratico, quello riguardante l’inclusione contro ogni forma di barriera (non solo architettonica, ma soprattutto sociale e culturale).
Ho accettato con orgoglio questo incarico con la speranza di fare del mio meglio. L’ho fatto perché sono certo che questa nuova Primavera del PD, con Elly Schlein segretaria, saprà stare al fianco di tutte le persone, a partire dalla tutela dei diritti di ogni minoranza.
Come sempre in questi anni, lavorerò affinché le etichette non abbiano più senso di esistere: per questo la disabilità sarà solo uno dei tanti aspetti che affronteremo in tema di parità, andando contro a quella categorizzazione che piace tanto a questo Governo di Destra che, addirittura, continua a valorizzare un Ministero “ad hoc” discriminante e retrogrado.
In questo, il Dipartimento che avrò il piacere di guidare come responsabile dovrà essere un esempio virtuoso: occorre lavorare per tutte e per tutti, senza pietismo e senza compassione, guardando soltanto alle persone e alle loro identità.
Grazie a Elly per la fiducia, grazie alla Comunità Democratica e grazie a tutte e tutti voi che ogni giorno mi sostenete e che sarete parte fondamentale di un contributo collettivo. Perché così mi piace e perché in questo credo, nella potenza dell’“insieme”.
Un abbraccio, e al lavoro!
#EllySchlein #PartitoDemocratico #PD #SegreteriaPD #Dipartimento #Inclusione #Diritti
@fia you have embarrassed yourselves today with @F1 What an unnecessary mess.
Please remember everyone, this is a sport first and entertainment second, not the other way around.