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More pertinent today than ever…..

thecuriousastronomer

It was announced a few days ago that the American sprinter Justin Gatlin is on the shortlist for the IAAF (International Association of Athletics Federations) “Athlete of the Year” award for 2014. This is largely due to his having set the fastest times over both 100m and 200m this year; faster than Usain Bolt, faster than Yohan Blake, faster than anyone. In fact, he has set 6 of the 7 fastest times over 100m in 2014! Also, he has run faster over both 100m and 200m than anyone one else in their 30s (he is 32). Ever. But, should Gatlin be considered by the IAAF for such a prestigious award? Should he be even allowed to compete at all?

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For those of you not familiar with Gatlin’s athletics career, he has twice been banned for failing drugs tests. In 2001 he failed a doping test, testing positive for amphetamines. He…

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Tomorrow morning (Disunited Kingdom and Namibian time) the British & Irish Lions will play the 1st Test of their 2017 tour against New Zealand’s All Blacks. It is a much anticipated match, one of the most important in which most of the players will take part. 

My first rugby memory is of the 1971 Lions tour of NZ, the only time that the Lions have won a Test series there. Of course, as a 7-year old I did not realise that the 1971 tour was, and would remain, so historic. 

I didn’t say that I was witnessing history, as live TV of sporting events occurring on the other side of the world did not exist in 1971. At least, not for rugby. So we listened live on the radio, at 4am (as matches were played mid-afternoon local time). Later in the day, highlights would be shown on TV, which we also watched even though we knew the score. 

The “we” were myself, my two sisters and my parents. My father gave us no choice in whether we were woken up to listen to the Test matches in 1971; refusal was not an option. 

The 1971 tour remains burned in the minds of so many rugby fans, and not just supportes of the Lions but those of the All Blacks too. Many Kiwis of my age will tell you that their rugby heroes were Barry John, Gareth Edwards, Gerald Davies or J.P.R. Williams, not the men who represented New Zealand at that time. 

This 2017 tour is not only a chance to get that second series win, It is also a chance for Kiwi Warren Gatland to put one over on his native country and put himself at the head of the list to succeed Steve Hansen as the next All Blacks’ coach. Here is the team chosen for the 1st Test. 


To many people’s surprise, Leigh Halfpenny and George North have not been included. Gatland and his coaching team have, instead, gone with a far more attacking back three. The other major talking point is Allan Wyn Jones’ inclusion ahead of Maro Itoje, but I’m not surprised by this. Although Itoje has been in great form, Alun Wyn is one of the most experienced and best locks in World rugby. Tour captain Sam Warburton had pretty much declared himself out of contention to start the 1st Test, feeling that he’s not yet fit enough. 

If the Lions can win the 1st Test then it will be a huge result. Not only will it make winning the 3-Test series a real possibility, but it will also be the first time that the All Blacks have lost at Eden Park since 1994! A loss by the All Blacks would send shockwaves through New Zealand rugby. The Lions need no greater motivation to play the game of their lives. 

Continuing my countdown of the 30 greatest Bob Dylan songs according to the Daily Telegraph, today I am covering the songs from numbers 10 to 6. These are

  • 10 – Knockin’ On Heaven’s Door
  • 9 – Ballad Of A Thin Man
  • 8 – Hurricane
  • 7 – Visions Of Johanna
  • 6 – Like A Rolling Stone
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Bob Dylan granted his first interview since being awarded the 2016 Nobel prize in literature to Edna Gundersen.

10. Knockin’ On Heaven’s Door (1973)

This song has become very well known through cover versions, in particular the versions by Bob Marley and Guns ‘n’ Roses. As with most cover versions of Dylan songs, I have to say that I prefer the original (but I also know that I’m biased!). There is a simplicity and starkness to Dylan’s original, which is lost in the two more famous cover versions.  After saying that, I do think both cover versions are great, and the Guns ‘n’ Roses version is one of the few songs done by them that I like.

From the soundtrack of a violent Sam Peckinpah western, in which Dylan once again demonstrated that acting is not one of his many talents, comes this elegiac classic. It rides on a simple, repetitive chord progression and has a ridiculously swift fade out but conveys such a spirit of bittersweet farewell to life it has become one of rock’s most universal anthems.

9. Ballad Of A Thin Man (1965)

This song is believed to be a cutting criticism of an out-of-touch newspaper reporter, and was written during a period when Dylan was showing a different side to his song writing. A side in which he was laying bare his frustrations with the people who didn’t understand him, or the societal changes which he was spearheading. When he sang this song in concert during his infamous world tour of 1965-66, the anger in his voice was clear to all who listened (rather than those who were booing him for “going electric”).

It is comical to consider that Sixties Dylan is so associated with the peace and love ethos of the hippies. Over an ungainly, almost lumpen piano motif, Ballad Of A Thin Man heaps surreal scorn on some self-regarding representative of the straight world baffled by the inscrutable counter-culture. Dylan’s vocal drips contempt. “Something is happening and you don’t know what it is, do you, Mr Jones?” He sounds like the original punk.

8. Hurricane (1976)

Is there a songwriter who can weave a story as masterfully as Dylan? The story in this song, however, is shockingly true. It tells of the incorrect conviction and imprisonment of Ruben Carter, a boxer who was also known as the Hurricane. The song is the opening track on Dylan’s 1976 album Desire, which is one of my favourite Dylan albums. A movie was later made of Carter’s life, with this as the opening song.

“Pistol shots ring out in the barroom night…” Hurricane marked a thrilling late flourish from Dylan the protest singer, moved to write by the flagrant framing of champion black boxer Ruben Carter (finally exonerated in 1985). The dramatic temperature of this forensically bitter narrative (composed with Jaques Levy) is matched by wild violin flourishes from beautiful novice Scarlet Rivera, who Dylan picked up walking in the street on the way to the recording session.

7. Visions of Johanna (1966)

This song is simply mesmerising. The opening lines “Ain’t it just like the night to play tricks / When you’re trying to be so quiet” are masterful. Although I like the studio version which appears on Blonde on Blonde a lot; when I heard the acoustic version that he did in concert in May 1966 in Manchester (the famous “Royal Albert Hall” concert, with the Judas heckle), I was simply blown away by the haunting power of that live version. Bear in mind that, when he performed this in May 1966, the audience didn’t know the song at all as Blonde on Blonde had not yet been released.

“Inside the museums, infinity goes up on trial.” Dylan at his most expressive and elusive, slipping in and out of the cracks of his own lyrics as he holds contrasting romantic muses in the balance. “I do know what my songs are about,” he insisted to an interviewer from Playboy magazine. “Some are about four minutes, some are about five minutes, and some, believe it or not, are about eleven or twelve.

6. Like A Rolling Stone (1965)

In Rolling Stone Magazine’s list of Dylan’s greatest songs, as well as their list of the greatest songs of all time, “Like A Rolling Stone” is at number 1. The Telegraph puts it at number 6, so you will have to wait and see which songs they put above it. When released in 1965, this song was the longest song ever released as a single. It was also Dylan’s biggest chart success. He finished the set of each concert in his 1965-66 world tour with it. Sometimes, the incessant booing which accompanied the second half of the show (the “electric” half) would cease during this song, as it was such a big hit in the USA and Europe.

“That snare shot sounded like somebody’d kicked open the door to your mind” is how Bruce Springsteen recalled first hearing this at 15 years old. This thunderous six-minute rock epic marks the moment when the young protest singer emerged as something popular music had never witnessed before. The vocal is as fierce and relentless as the flowing, spitting lyric, a tale of a fallen society princess adjusting to a disorientating new reality. “How does it feeeel?” Dylan demands. Many of us are still wondering about that.

Knockin’ on Heaven’s Door

The song which I have chosen to share today is “Knockin’ on Heaven’s Door”, as it is the only one which is on Dylan’s official Vevo channel. This version is from his MTV Unplugged concert, which he did in the mid-1990s. Enjoy!

Tonight (Friday 10th March), Wales take on Ireland in Cardiff in the 2017 6 Nations clash. It is the first match of the penultimate weekend of this year’s 6 Nations, and a Friday evening clash in Cardiff usually has a special atmosphere. Wales have lost two matches from three, with their heavy defeat at Murrayfield two weekends ago still being picked over by the rugby media and pundits in Wales. This means that we are out of contention for this year’s 6 Nations title, but there is more than pride at stake.

The 2019 World Cup draw will be made in the next few months, and if Wales do not win at least one of their remaining two matches in the 6 Nations they risk dropping out of the top 8 in the World rankings. This means that they will be drawn in the same group as two higher ranked teams, with one team from the top 4 and the second team from 5-8. This was the situation we faced in the 2015 World Cup, being drawn in the same group as Australia and England.

This has left Welsh interim-coach Rob Howley with a difficult decision to make. There have been calls for him to try starting players like Sam Davies at outside half, with the 6 Nations title now out of reach. But, we cannot afford to lose either of our two remaining matches because of the World Cup draw. So, despite most people in Wales calling for some changes to the starting 15, Howley has decided to keep exactly the same 23 as he did against Scotland, with the same starting 15 too.

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Wales take on Ireland this evening in Cardiff. Wales will be looking to salvage a very poor 2017 6 Nations campaign.

Ireland, on the other hand, are still in with a chance of the 6 Nations title. Win in Cardiff tonight and it will come down to a probable title-decider against England at home in Dublin on Saturday the 18th. Based on their performances in their 3 matches so far, I think Ireland will be too good for Wales. Of course I want to see a Wales victory, but unfortunately I think Ireland are going to win. Whoever wins, it should be a very exciting match.

The 3rd weekend of the 2017 6 Nations saw home victories in all three matches. Scotland beat Wales at Murrayfield, Ireland beat France in Dublin, and England beat Italy at Twickenham.

Scotland v Wales

Scotland beat Wales for the first time since 2007, with a well-deserved win that saw them score 20 unanswered points in the 2nd half. Wales went into half-time with a slim 13-9 lead. It could have been more, with Wales missing a chance to go 16-6 up with only a few minutes left of the first half. Instead, Scotland scored a penalty just before half-time and instead of 16-6 it was 13-9.

If ever there was a game of two halves this was it. The second half saw Scotland score 20 unanswered points, including two well deserved tries. It is true that Wales did have their chances to score points in the 2nd half, but Scotland were by far the better team after the break and fully deserved their victory over a largely ineffective Welsh team.

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Scotland beat Wales 29-13 in a well-deserved victory, their first win over Wales since 2007.

Whereas the Scottish team took their chances, Wales were unable to come away with points when they were in the Scottish 22. It was a poor performance by Wales, but also a very good one by Scotland. After being uncompetitive for most of the last 10 years, it is good to see Scotland back mixing it with the other countries in the 6 Nations.

Ireland v France

This was a cracker of a match. For a neutral, it had everything. Ireland went into half-time with a narrow 7-6 lead, and it was not clear well into the second half who was going to win this keenly contested match. In the end the better play of Irish half-backs Connor Murray and Johnny Sexton proved decisive, Ireland emerging victorious 19-9. With first Ireland, and then France, being the last two sides that Wales will face, the performance of both teams in this match does not bode well for Wales’ chances of winning either match, in my opinion.

England v Italy

I have not seen this match, but am looking forward to seeing the highlights, mainly for the tactics which Italy adopted. By not committing any men to the breakdown, they avoided any rucks forming and thus the off-side line which normally exists did not apply. This allowed them to have men standing between the English backs, completely disrupting the game that England hoped to play. In fact, so effective was this tactic that Italy were 10-5 ahead at half-time. It is, apparently, only in the second half that England got to grips with this novel tactic, and eventually ran away to win 36-15.

The 4th weekend

The 6 Nations now has another brief hiatus, before the next round of matches in just under two weeks. Ireland come to Cardiff to play Wales on Friday evening (10th March), then on the Saturday Italy take on France before the big game of the weekend, England v Scotland. Not only is this for the Calcutta Cup, but both countries are going for the Triple Crown. It will  be the first time in probably some 20 years that Scotland will go to Twickenham with even the slightest hope of winning.

Based on our performance against Scotland, I cannot see Wales beating Ireland, which leaves us with the real possibility of finishing the 2017 6 Nations with only one win. Quite where this will leave the Welsh team and management is a good question,  but it is clear from our performances this season that Wales have not developed the creativity in attack which is needed to win matches. Scotland showed us how it should be done; all we could do was look on and marvel at how much they have developed and how much we have regressed.

 

This weekend sees the 2017 6 Nations come out of its hiatus for the 3rd weekend of matches. The weekend kicks off with Scotland v Wales at Murrayfield, followed by Ireland v France in Dublin, and Sunday sees England v Italy at Twickenham. It is an important weekend in the Championships, particularly for Wales, Scotland, Ireland and France. Win this weekend and their records will be 2 wins from 3, but lose and it will be 1 win from 3, a big difference.

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This weekend is an important one in the 2017 6 Nations. For Wales, Scotland, Ireland and France it will make the difference between being 2 wins from 3 or 1 win from 3.

Scotland v Wales

Wales go to Murrayfield having not lost to Scotland since 2007, either home or away. George North comes back into the team that lost to England, after injury kept him out of that game. Otherwise the Welsh team is unchanged, with perhaps the biggest surprise being that Ross Moriarty keeps his starting position, forcing Taulupe Faletau to start on the bench. Given how well Moriarty played against England I think it is the correct call by Rob Howley.

This will be the sternest test Wales have had against Scotland in the last 10 years, and they will need to be at their best to beat a resurgent Scotland. It will be a fascinating encounter, and I am going to be on the edge of my seat watching it.

Ireland v France

Ireland will be wanting to continue getting their 2017 campaign back on track after their opening loss to Scotland. They beat Italy easily in the 2nd weekend of matches, so if they can beat France their campaign to win the 2017 Championship will still be possible. Lose and they can forget about being crowned champions. France too will be wanting to make it 2 wins from 3, and an away win against Ireland would be a scalp to bolster their confidence of being in contention for the Championship title come the final weekend.

England v Italy

Sunday’s game seems England play Italy at home. This should be a rout, it is really just a question of how many points England can put on Italy. There has been a lot of debate this Championships as to whether Italy deserve to be part of the 6 Nations, and this match will probably do nothing to quell that debate. I expect a cricket score of 60+ points for England.

 

Last week, I blogged about the theoretical arguments for the Galaxy harbouring a supermassive black hole at its centre, and here I blogged about the observational evidence. The work done by the UCLA and MPE teams, discussed here, has led to a determination that the central black hole has a mass of between 4.4 and 4.5 million solar  masses. I am going to take the upper end  of this range, just for convenience.

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An artist’s impression of Sgr A*, showing the central supermassive black hole and the accretion disk which surrounds it.

The size of the event horizon

In this blog here I showed that the radius of a blackhole’s event horizon can be calculated by using the equation for the escape velocity v_{esc} when that velocity is equal to the speed of light c. That is

v_{esc} = c = \sqrt{ \frac{2GM }{ R } }

where M is the mass of the blackhole, G is the universal gravitational constant, and R is the size of the object, which in this case is the radius of the event horizon (also known as the Swarzchild radius R_{s}). So, we can write

R_{s} = \frac{ 2GM }{ c^{2} }

Putting in a mass of 4.5 million solar masses, we find

R_{s} = 1.33 \times 10^{10} \text{ metres}

Converting this to AUs, we find the radius of the event horizon is 0.09 AUs, much smaller than the radius of Mercury’s orbit, which is about 0.3 AUs.

At the distance of the Galactic centre, 8 kpc, this would subtend an angle of
\theta = 6.17 \times 10^{-9} \text{ degrees} (remember to double R_{s} to get the diameter of the event horizon). This is the same as

\boxed{ \theta = 22.22 \text{ micro arc seconds} }

Converting this to radians, we get

\theta ( \text{in radians}) = 1.08 \times 10^{-10}

In fact, we do not need to resolve the event horizon itself, but rather the “shadow” of the event horizon, which is about four times the size, so we need to resolve an angle of

\theta ( \text{in radians}) \approx 4 \times 10^{-10}

The resolution of a telescope

There is a very simple formula for the resolving power of a telescope, it is given by

\theta( \text{in radians}) = \frac{ 1.22 \lambda }{ D }

where D is the diameter of the telescope and \lambda is the wavelength of the observation. Let us work out the diameter of a telescope necessary to resolve an object with an angular size of 50 \times 10^{-4} \text{ radians } at various wavelengths.

For visible light, assuming \lambda = 550 \text{ nanometres}

D = \frac{ 1.22 \times 550 \times 10^{-9} }{ 4 \times 10^{-10 } }, \boxed{ D = 1.68 \text { km} }

There is no visible light telescope this large, nor will there ever be. At the moment, visible-light interferometry is still not technically feasible over this kind of a baseline, so imaging the event horizon of the Galaxy’s supermassive blackhole is not currently possible at visible wavelengths.

For 21cm radio radiation (the neutral hydrogen line)

D = \frac{ 1.22 \times 21 \times 10^{-2} }{ 4 \times 10^{-10 } }, \boxed{ D = 640,000 \text { km} }

This is more than the distance to the Moon (which is about 400,000 km away). So, until we have a radio dish in space, we cannot resolve the supermassive blackhole at 21cm either.

For millimetre waves, we have

D = \frac{ 1.22 \times 1 \times 10^{-3} }{ 4 \times 10^{-10 } }, \boxed{ D = 3,100 \text { km} }

which is feasible with very long baseline interferometry (VLBI). So, with current technology, imaging the event horizon of the Milky Way’s supermassive blackhole is only feasible at millimetre wavelengths. Millimetre waves lie in a niche between visible light and radio waves. They are long enough that we can do VLBI, but they are short enough that the baseline to image the supermassive black hole’s event horizon is small enough to be possible with telescope on the Earth.

Next week I will talk about a project to do just that!