Fixed that for you. 
Sorry I assumed that was a given
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Oh, and you can’t accelerate constantly at 15m/2 because if you do you will exceed light speed - what actually happens is that you need to put exponentially more energy in as you approach light speed.
Ah, I think I got my sums wrong above - it’s not as long as 6 years, less than a year (212 days if I have it right this time - think I divided by 1.5 instead of 15). So the round trip is more doable than I thought. That doesn’t fix the problem of building a spaceship from scratch with a novel, never before used propulsion system, in a couple of months.
They reach ~.995c in the book and then flip
It is 4 years or so with some alien flashbacks or something I’m trying to avoid too many spoilers
The film makes it look much less. Clearly the book tries harder with the physics and the film blows most of that effort away.
Mmm, that makes the “relativistic mass” factor 100 - i.e you have to put in 100x more energy to keep accelerating which makes it less plausible.
You can’t do the journey in less than 11.9 years (as observed from Earth) and that’s ultimately what matters - that you get there and back (or at least send data back) in less than 30 years.
Having re-calculated - 212 days acceleration at 1.5g gets you to 0.92c covering 3x10^12km or 2.2% of your journey. The deceleration at the other end also covers 2.2% in 231 days. For the middle you can coast at 0.92c for 12.35 years - total journey time 13.5 years. So that bit is doable if you can accelerate at 1.5g for long enough - not sure you need to reach .995c or that you need to accelerate to the mid point and that just complicates things energy wise for a relatively small gain in journey time.
I can see online it says constant acceleration for half the journey - not sure if the author worked through the maths (I’ve probably made another mistake somewhere)
Energy to do it - ignoring relativity (because I think that means integrating the relativistic mass equation m = m0 / √(1-v2/c2)) which is beyond me).
F=ma so, as the craft is said to weigh 2100 tonnes we need to generate a force of 15*2100000 or 3.1x107N or just a smidge less than the thrust of a Saturn V so we’ve built rockets that big (just not ones which also burn for a year and a half).
Work=Force x distance so we need 3.1x107 x 2.995850596×10¹⁵ joules. Oh, twice for the accelerate/decelerate phases.
Give or take 2x10^23 Joules. Actually we’d need more because of relativistic mass kicking in.
Even without that it’s the equivalent of 1.2 trillion tonnes of gasoline. The US produces about 1/12000th of that a year.
Astrophage - if I was paying attention (which I admit I wasn’t) can release enough energy from 20μg to melt 1 tonne of steel. Let’s say that’s at 1500°C Heat capacity is about 500J/kg/°C, latent heat of fusion another 247 kJ/kg
So that’s 1000x1500x500+1000x247x1000 = 997MJ (9.97x108J
OK, so if that’s a 20μg you’d need 2x10^23/9.97x108 *20μg
Which is 3786 tonnes.
I’ll check my working tomorrow
As I said the energy cost/mass is meaningless because it is alien tech and can produce nearly infinite energy with almost no mass
Also the travel time is ~13.1 years(earth time)
Antimatter
Churning through these recent threads seems to have taken an eternity. Is that due to relativity? Whether it is relative to the subject of the thread or not! 
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Yes … and no.
You can come up with a journey profile which gets you there in the necessary timeframe and with accelerations which don’t turn the crew into mincemeat.
To do so requires a craft which can achieve 0.92c (or 0.995c) and harness an energy source which involves direct matter->energy transition (a bit more research into the plot shows this is how “astrophage” is supposed to work).
You’d have to build the craft in low Earth orbit - which has never been done (well, ISS I suppose but that’s 1/5th of the size). You have to get 2100 tonnes of material (100tonnes for the living quarters and fuel tanks and 2000 tonnes for the astrophage fuel) into LEO which is 30-50 trips in super heavy lift vehicles - way in excess of current launch capacity.
AND you have to harness a fuel source which is ocmpletely alien, works like nothing we’ve used before and, if it goes wrong, is going to leave a planet busting sized hole in your plans (the energy involved is over a million fold that of the meteor strike which left a hole in Arizona). And all in a timescale of a couple of years.
That’s what makes it science fantasy.
We enjoyed this series.
I have an app that announces the time in my hearing aids every hour. I swear it is the voice of Ann Droid.
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A Canadian writer, Yann Martel, wrote ‘Life of Pi’ in the 1st person, from the perspective of an Indian boy, Piscine Molitor Patel. I read the book which captivated me, years ago. Saw the film later, then reading the book again recently I heard a delightful Indian lilt in the words, even though the author was Canadian.
Something about the film, its superb graphics, the Indian accent throughout, has coloured the words.
Worth reading and seeing the film as well IMO.
Note added: the film depicts a few limited sequences of upsetting animal to animal savagery, so be warned.
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We go to the cinema at least once a month on the premise that we want to be entertained rather than anything else, PHM was good and Gosling is underrated.
@billybutcher just let yourself go once in a while even for a couple of hours.
Thanks Tim, love you too.
Watched ‘Welcome to the Punch’ a 2013 film with some good people in it. Excellent film.
Also we’re on the second series of ‘ After the Flood’ - it’s a series that’s worth watching.
It would be extremely helpful if, after a recommendation, SFers explained where they watched it e.g. Netflix, Iplayer, local cinema etc and also which country. Netflix UK is not the same as Netflix France.
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Watched episode one of the Lockerbie Pan Am bombing drama on Netflix earlier. Bit boring as we all know the outcome of who was involved already and to me it was based on two UK police officers trying to outdo one another by fighting to be in charge. Don’t think I will continue with the following episodes that are on there to watch. My Netflix is from the US
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As I found out. I can’t watch the NYT’s Netflix recommendations.
Saw the Odyssey at an IMAX yesterday. Sound level so high I had to block my ears.
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Son in law hated it, full of woke stuff he cannot stand so he had a snooze instead as the seats over there recline almost flat
Woke stuff? What do you mean?