Monthly Archives: April 2022

Electrons and Positrons

I have known about Electron–positron annihilation for at least 52 years, from my course in Atomic and Nuclear Physics at Carleton College in the spring of 1970 if not before. The reaction is

e + e+ → γ + γ

I had always assumed that the inverse reaction

γ + γ → e + e+

was also possible because of time reversal symmetry. Apparently so had everyone else, but it has only recently been observed: Matter arises from light? We finally know the answer to this question!. Even now there is a caveat about “virtual” as opposed to “real” photons.

Slackware Diary – 2

Continuing from Slackware Diary – 1

Fixed the prompt by copying .bashrc and .profile (renamed as .bash_profile) from my primary Ubuntu system. This works and I have nice color prompts in Slackware. Need to see if I have scripts from my previous Slackware days to add environment variables, aliases, etc. Life in Slackware means a lot of time on the command line.

The next task on my list was to install Flatpak so I could use apps from Flathub

“Failure is always an option.”-Adam Savage

Rang Gaeilge, 20ú lá mí Aibreáin 2022

Duinnín agus Imleacán Kali (tuilleadh)

Dineen and the navel of Kali (continued)
  • ‘Rugadh agus tógadh Marie i Sr. Cuffe agus is ansin atá cónaí ormsa. Baisteadh Marie i Sráid na mBráithre Bána. Dhein sí a céad chomaoineach ann. Tá ag éirí go maith le Mr. McCausland sa bhanc agus thóg se an teach seo ar cíos anuraidh. Ar ndóigh, ní bheinnse ag seadú anseo ach go bhfuil gá ag Marie le cúnamh agus Mr. McCausland san … ospidéal.’

    ‘Marie was born and raised in Cuffe Street and that is where I live. Marie was baptized in Whitefriars Street. She made her first communion there. Mr. McCausland is doing well in the bank and he rented this house last year. Of course, I wouldn’t be here except that Marie needs help and Mr. McCausland is in the … hospital.’

    comaoineach Communion f
    cíos rent m
    seadú Settlement; stay, wait m
    cúnamh help m

    Léigh tuilleadh

  • Installing Slackware 15.0

    Back in February I looked at the Slackware Linux web site. After years of working with Ubuntu, and occasionally its parent Debian, I decided to see if I could install Slackware and get it to work. I used it a lot in the first years of the current century. Could I still manage it now, or had the comforts of the Ubuntu installation process dulled my edge? From Slackware 15 – The old brigade:

    Slackware is deployed using an ncurses interface, with a set of menus where you must make intelligent choices, including partitioning and package selection. And then, there’s LILO the bootloader. Not GRUB, mind! Feels a bit daunting, but then, if you’re careful and methodical, there should be no issues. That said, the approach automatically precludes Slackware from being a typical desktop choice, as most people would have no idea what to do with the installer.

    Continue reading

    Rang Gaeilge, 30ú lá na Márta 2022

    Duinnín agus Imleacán Kali

    Dineen and the navel of Kali

    Nodlaig, -lag, pl. -i, f. , oft. with art … .
    N. mhaith chughat, I wish you a merry Christmas…

    • Seachtain roimh Nollaig. An aimsir an-mhíthaitneamhach ar
      fad. Gálaí gaoithe, ráigeanna baistí, flichshneachta. An Duinnineach
      ar a bhealach isteach go hEaglais na mBráithre Bána. Bhí
      sé thart ar a haon agus ba léir go leanfadh an lá anfach, fliuch. I
      halla mór na hEaglaise, bhí go leor pramanna, báibíní ina gcodladh iontu,
      teachtaireachtaí carntha orthu. Bhí daoine, mná don
      chuid is mó de, ag rith isteach chun faoistine nó ag lasadh
      coinnle: ullmhú i gcomhair na Nollag faoi lán tseoil.

      Week before Christmas. The weather was thoroughly unpleasant. Gales of wind,
      sudden outbreaks of rain, sleet. Dineen was on his way to the WhiteFriars’ church.
      It was about one and it was clear that the rainy, wet day would continue.
      In the great hall of the Church, there were many prams, babies sleeping in them,
      messages piled on them. There were people, mostly women, running in to confession or lighting up candles: preparation for Christmas in full swing[sail].

      míthaitneamhach Displeasing, disagreeable; unpleasant, unattractive
      ráig udden rush; sudden outbreak; fit, bout, attack f pl ráigeanna
      flichshneachta sleet m
      anfach Stormy, rough, tempestuous
      teachtaireacht message f
      carn heap, pile v
      faoistin confession f
    • Léigh tuilleadh