When is the real Easter?

The date of Easter has long been a subject of dispute. It was one of the issues at the Synod of Whitby, which took place in 664. This year, Easter is particularly early. The Orthodox Easter and the Jewish Passover are a month later. This discrepancy dates back to 1582 and the replacement of the Julian calendar by the more accurate Gregorian calendar. The Orthodox churches mostly retained the Julian calendar, which is now twelve days late. Thus they are celebrating Christmas when everyone else is celebrating the Feast of the Epiphany. Only occasionally do the two occur at the same time.

The western churches fix Easter Sunday to the first Sunday after the first full moon following the vernal equinox, the latter being on 19th, 20th or 21st March. If a full moon occurs just before the vernal equinox, an additional lunar month is effectively inserted before Easter, which will then occur at a late date and correspond with the Orthodox Easter and the Jewish Passover.

It would in principle be an excellent expression of Christian unity if all the churches celebrated Easter at the same time, which logically and for the sake of historic authenticity would correspond with the Jewish Passover. However, this brings us to the Jewish calendar, which is a lunar calendar. A lunar year is 353 days, ie 11 days short.of a solar year, and additional months are therefore added to correct the shortfall. The extra month in the Jewish leap year is called Adar Sheni - the second Adar, and seven of these occur within  a 19 year cycle, on the 3rd, 6th, 8th, 11th, 14th, 17th, and 19th years.

This 19 year cycle is quite accurate but it is not perfect. The average length of the Jewish year over a 19 year cycle is about 365 days, 5 hr, 55 min, 25.4 sec. This is 6 min, 40.2 sec longer than the current average value of the solar year (though that is changing very slowly) and 6 min, 13.4 sec longer than the average value of the year in the Gregorian calendar (which is itself slightly too long). As a result, the average date of the first day of Passover is getting later by one day in about 216 years compared to the Sun and 231 years compared to the Gregorian calendar. Thus it is already on average a few days later than 2000 years ago.

In a 19 year cycle, Pesach currently occurs a month later than on the first Full Moon after the vernal equinox in the 8th, 11th and 19th year of each 19 year cycle, such as 2005, 2008 and 2016. This accounts for the discrepancy.

Thus an important question regarding an agreed date for Easter is whether the desire for unity should outweigh considerations of astronomical accuracy?

Comment was free

The Guardian's comments section goes by the title "Comment is Free". Only it is no longer. Most of the many articles following today's terrorist attack have not been open for comments on its web site. The sort of comments that would be made would not be supportive of the Guardian's "narrative", the yarn it has been trying to spin for the past five years.

Paris, Brussels, where next?

The expected has happened. London is probably in the terrorists' sights. I suspect that the British will take one more serious incident on the cheek, but the one after that will be followed by a wave of thuggery against anyone who looks as if they might be a muslim, together with attacks against their property. After that it will be tit-for-tat.

People expect to be able to go about their daily business without the risk of being killed or maimed. If politicians do not act effectively and decisively, then vigilante groups will take matters into their own hands. That is the route to a breakdown in civil order.

This is one of those situation where the Jews are the canary in the cage. First they came for the Jews... and Islam comes with antisemitism built-in. The Israelis have had to deal with this same situation for the past couple of decades. Their solution - and it has only been a partial solution - has been to take draconian measures which have led to accusations of apartheid. Although they have been accused of it, there has not been ethnic cleansing, concentration camps and genocide. However, the innocent have certainly suffered along with the guilty as the entire community has come under suspicion.

Where should the suspicion stop? As Mao famously pointed out, the terrorist swims in the sea of the people. If the community will not root out and disown the fanatics in its midst, they are going to pay the price. Ultimately, it is their choice. We also have a own choice. We can continue to pretend it is a fringe issue, but in the face of this threat - and it is a very old one - politicians must be prepared to do what is distasteful and at least follow the Israeli example if anything like normal life is to continue. If they do not act now and do the minimum needed to preserve public security, then pressures will build for measures that would be infinitely worse.

Almost 4,000 people referred to UK deradicalisation scheme

"Almost 4,000 people referred to UK deradicalisation scheme last year", run a Guardian headline. According to the article, "Children aged nine and under were among 3,955 people reported to Channel in 2015, up from 1,681 in 2014".

The article, which is not open for comments, does not say what sort of radicalisation they are suspected of. Are they radical Christian Scientists, who have been inspired by reading Science and Health by Mary Eddy Baker, believe that everything is spirit and refuse to go to the doctor or take their medicine?

Are they Catholics, who are open to variety of possibilities for radicalisation? Boys as young as five have been known to turn a coffee table into a pretend altar, dress themselves in a piece of white, red, green or purple curtain material and play at celebrating Mass. Are they having to be restrained from absconding to join the Franciscans and insist on serving the homeless on the local soup run instead of doing their homework. Or are they aspiring Benedictines, who are spending every moment of their spare time learning church Latin and poring over the Liber Usualis, keeping their parents awake chanting the office of Matins in the small hours and Compline last thing at night, waiting only for the day they can enter a monastery as postulants?

Or are they radical Anglicans, who instead of going home after school, pester their parents to attend evensong at their local cathedral?

Then there are radical Jews - thirteen year old boys, fervent after their barmitzvahs, who wake the whole household when they get up at the crack of dawn to put on their phylacteries and say their morning prayers, whilst the radicalised Jewish girls drive their mothers mad, demanding strict kashrut in the kitchen, with only glatt-kosher food, separate plates, cutlery and pans for milk and meat, and separate sinks for washing up.

Dangerous stuff, this radicalisation.

Crossrail 2

Crossrail2 is a project for a new cross-London railway running roughly from the south-west to the north-east. It is not a vanity scheme in itself - on the contrary, it is a long-overdue construction of a project first put forward in 1904 and from time to time ever since. It links together existing routes which at present running to Waterloo, by diverting them into an underground route northwards to Seven Sisters and Tottenham. Amongst other benefits, this will reduce pressure on congested Waterloo.

There are questions, nevertheless. From the south-west, four separate routes converge into one, which is always a potential source of operating difficulties. At the northern end, the line splits into two, which means that some of the trains arriving from the south will have to turn back before they get to the end of the route, probably at Tottenham or Seven Sisters.

More seriously, should it be built as a full-scale railway with overhead electrification, or as a tube? The former, with 6 metre diameter tunnels, involves excavating three times as much material as a 3.5 metre diameter tube.

A related issue is the choice of electrification. The routes from the south-west are already electrified with a 750V DC conductor rail supply. If this were continued throughout the length of the tunnels, the latter could be constructed to a 5 metre diameter instead of 6 metres, ie only 70% of the excavation volume. A conductor rail DC system would also avoid having to fit the trains with heavy transformers, as well as providing greater reliability and reduced maintenance costs, since conductor rail electrification is almost a fit-and-forget arrangement.

The argument usually given for 25KV electrification is that it is more energy-efficient, which is true over long distances where transmission loss becomes an issue at low voltages due to the much higher currents. However, Crossrail 2 is a short-distance railway and transmission losses are not going to be so significant.

Brexit perils

These are some of the things that will happen if Britain leaves the EU

• A meteorite will land in the middle of the pitch at Lord's at the start of the season, making a huge crater. All cricket matches will have to be cancelled for the rest of the year, and trains from Baker Street and Marylebone will have to be replaced by buses for several months.
• The Straits of  Dover will be blocked with icebergs.
• A 60 foot high tidal wave will sweep up the English Channel leaving a trail of destruction along the south coast.
• A volcano will appear in the middle of Slough and start to erupt.
• A major city in the Midlands will be destroyed by an earthquake.
• Kittens will die.
• The sun will stop shining for five years.

There is probably more, but you would need to look in Old Moore's Almanac.