Sunday 31 December 2017

The Holdo Maneuver

So first, ***SPOILERS***, do not read on if you don't want to read a major spoiler about Star Wars: The Last Jedi.

Okay, it's been out for several weeks now but better to be safe than sorry!







Also quick disclaimer before going on, these are just my thoughts around the issue, I've got a PhD in astrophysics and have written about this stuff before (e.g. http://astrojje.blogspot.co.nz/2016/07/science-of-sci-fi-spaceflight.html) read and watched more sci-fi than I probably should have and completed X-wing, TIE fighter and X-wing alliance, again, more times than I should have. So I do love Star Wars and really like thinking not of the problems with science fiction but with "how could they possibly happen".

Anyway, one of the main scenes in the movie is when Admiral Holdo takes the Mon Calamari cruiser "Raddus" and rams into Supreme Leader Snoke's ship by sending it to hyperdrive. The second I saw this I thought that it tells us something interesting about how this fictional hyperdrive works. After some thought and googling I found out many people were having similar thoughts, e.g. https://www.theringer.com/2017/12/20/16800970/vice-admiral-holdo-maneuver-the-last-jedi 

In case you're wondering what the aftermath looks like here's a link: https://cdn-images-1.medium.com/max/1600/1*fNvQQ4vnLNY6M_pnBsEEHw.png

But over doing the washing up I realised something, we've seen starship/starship collisions before. For example in Rogue One, https://www.youtube.com/watch?v=BZMepnUqpo8 where the collision between two Star Destroyers was "bad" for those ships.

Then even in Return of the Jedi there was the collision of a tiny little A-wing with a super-Star Destroyer (https://www.youtube.com/watch?v=lbsIUX2LoJQ).

In both these cases the velocities weren't at "hyperspeed" but the collisions were still bad. In the latter case mainly because of the collision hitting the bridge of the Executor.

A lot of people seem to have latched onto the fact that the Holdo Maneuver is the first to occur at light speed. However when you look at the damage to the mega-ship, it doesn't look so bad. The ship didn't suddenly explode it was just cut through. This looks quite similar to the star destroyer-star destroyer collision but at higher speed.

So here is the sciency bit - why did Admirial Holdo go to lightspeed? It was to make the collision happen quickly rather than allowing time for the First Order to move out the way. The energy of the collision wasn't enhanced due to the lightspeed it was just the time of the collision changed. This fact suggests the hyperdrive in the Star Wars Universe doesn't warp space but time? Or both maybe? So how it allows an object to travel the same distance that would take minutes at sub-light speed in a fraction of a second. Thus when the cruiser collides with the First Order ship rather than taking minutes or seconds as we've seen before it takes fractions of a micro-second. The trailing wake of material from the explosion is then what hits the other destroys behind the mega-ship.

If you want an analogy: think along the lines of someone punching a watermelon (=sublight collision) compared to a sword being slashed at speed through a watermelon and cutting it in half (=hyperdrive speed collision). Same energy (as a person throws the punch or turns the sword) but the speed is different. Actually, thinking on this more, a lot of martial art breaking techniques are more about speed than strength... but that's another post....

Another sciency thing her is that it means by the way that the hyperdrive doesn't remove a ship from spacetime like say the TARDIS does in Dr Who. But it means that there must be a similar solution, that we don't know of, that is how to "disconnect" one bit of spacetime from another, change the passage of time in someway and then "reconnect" them later without problems (this is impossible in our current understanding of the Universe).

Anyway the good news is this removes some of the problems what people have pointed out about the collision, namely "why did no one think of doing this before?". Well first, they have, just not with the hyperdrive engaged. Also let's think about this, a cruiser is an expensive ship, even if it's really old and ready for scrap, using one up as a weapon wouldn't be cost effective. There are many better (more cost effective) weapons that could be deployed.

Also let's think about mass. A tiny little fighter is maybe, 10 or 20 tonnes? A modern aircraft carrier on the Earth is about 100,000 tonnes, lets guesstimate that the Mon Calamari cruise is 1,000,000 tonnes. That's why the collision is so destructive, it's got 500,000 times more mass in that collision than a tiny little fighter would have. And its going to be more often that a person in a fighter would ram another ship in desperation than having a large carrier ship with only one person on board to decide their own fate

Summary: the hyperdrive didn't add destructive power, it just meant the collision (which we know already to be destructive) to just happen much more quickly.

There are other things to bear in mind here why no one developed "hyperdrive suicide robot ships". I think this comes down to cost and how difficult it is to build hyperdrives. The original TIE fighters didn't have hyperdrives or even shields. Even in the prequels the jedi starfighters needed to hook up to a special hyperdrive attachment. Hyperdrives are probably either expensive or difficult to make, if they don't add any destructive power it is probably more cost effective to put your money into making a bigger bang for your bomb.

Also then there are the safe guards that hyperdrives have which stop you if there is a large mass nearby. (I've played X-Wing, TIE Fighter and X-wing Alliance and have died in a mission many times when a star destroyer has blocked my exit vector, grrrrr). But you can always override them because as the article above points out, and suggestions in cannon dialogue gives you a "bad feeling" about collisions in hyperdrive.

One last thought though, if the hyperdrive does change time somehow, it means there might be some equivalence between distance and time taken to travel that distance, there might only be one speed of hyperdrive. This means that when in "A New Hope" Han Solo talks about doing the Kessel run in 12 parsecs, that has some direct meaning to time, not necessarily time, although that's still a complex and loaded statemtent.

Anyway, don't panic, we didn't see any new destructive tactic in "The Last Jedi", just a way of speeding things up.

Tuesday 26 December 2017

JJ's 2017 in review.

After writing a review like this last year I thought it'd be interesting to write another one!

Looking back to last year's review it was clear that in 2016 I thought I was working at my limit. This year I know I've gone way beyond that limit. Towards the end of the year I was almost unable to keep going. I was finding it impossible to find energy to start anything new and trouble keeping all the different streams of projects going through my mind. I don't think anything I did on it's own was too difficult but just the combination of multiple different projects was tough. Especially things way outside my comfort zone away from science research and teaching.

I could tell this work load did effect my family life too much. Being stressed and not having energy was a bad thing. Part of the issue was changes at home meaning that I needed to be home earlier than before which meant I had to try to be more efficient with my time and trying to juggle too many things.

Anyway, I survived and a number of things have been completed which means I don't need to worry about them any more. On the big plus side I did also get promoted to "Senior Lecturer above the bar" which is reward for doing so much work. While I still need to do more to get my next promotion in a few years it's good to already have a number of acomplishments. I just need to make sure I don't fill up my to-do list with more things that get in the way of research so much. Especially as I have a sabbatical second semester next year.

So anyway here is a (probably incomplete) list of everything I've done this year....

Research:
Service (astronomy):
  • Edited and published the proceedings for the IAU Symposium, #NZstars2016 which was run in 2016.
  • Took part in continuing discussions to set up Astro Aotearoa of research astronomers in NZ group. This led to the running of the first PhD summer school at Auckland run by myself with support from Nick Rattenbury and Richard Easther. Also the first science meeting which was also a success.
  • Won the Bronze Pleiades award for Auckland Physics Department in collaboration with the department’s equity working group. 
  • More public outreach talks at Stardome and Thames.
  • Curated @astrotweeps for a week again.
  • Refereed lots and lots of papers again and was named one of Nature's referees of 2016.

Service (University, Academia and wider):

Teaching:
  • Oversaw the redesign and teaching of second year courses in department of physics. This year we concentrated on lectures and examples classes. It will take a few more years to get perfect but we definitely improved all the courses and the students did enjoy the courses and seems to have done better (we still need to look in detail). Next year we'll be restructuring and organizing the labs....
  • Taught 5 courses: 2x 1st year astro (36 lectures), 2nd year classical mechanics (24 lectures, 8 example classes), 3rd year astrophysics (11 lectures) and course coordinated 2nd year electromagnetism. Considering the 2nd yr mechanics and 3rd yr astro meant I had to write two new courses in the same semester it wasn't easy and was quite stressful, especially when I wasn't able to keep so many things in my head at the same time but I made is somehow.
  • Finished of the course in Academic Practice, scoring A- grade overall. Again having to do this on top of everything else was difficult. Especially since my project work concerned trans and gender diverse people in academia which meant a serious amount of challenging self-reflection that made me quite uncomfortable, but I did learn a lot about myself at least. I still need to submit one of these projects to an education journal for publication maybe....
  • My 1st University of Auckland PhD student, Dr Lin Xiao, submitted her thesis, and passed. She has now moved back to China to take up a post-doc and she is finishing papers on the unpublished work in her thesis.
  • I still have 2 other PhD students who are close to finishing and submitting their theses early next year. I also now have a MSc student who is progressing through her project well and she should finish early 2019.
  • I did also apply for a University teaching award, I was unsuccessful in this but I did have to put together a teaching portfolio that allowed me to look at my teaching in detail. It allowed me to being to try to understand what it is I do when teaching that seems to be successful. I'll work out what "it" is one day I hope.