Anyhow, that was why I had requested a break from the deliberations, so I could spend some time with Dakk on her home territory. I had to get to know her – even though I felt increasingly reluctant to be drawn into her murky future.
She brought me to a new chamber, deep within the Spline ship. Criss-crossed by struts of cartilage, this place was dominated by a pillar made of translucent red-purple rope. There was a crackling stench of ozone.
I knew where I was. ‘This is the hyperdrive chamber.’
‘Yes.’ She reached up and stroked fibres. ‘Magnificent, isn’t it? I remember when I first saw a Spline hyperdrive muscle—’
‘Of course you remember.’
‘What?’
‘Because it’s now. This is my first time seeing this. And I’m you.’ Some day, I thought gloomily, I would inevitably find myself standing on the other side of this room, looking back at my own face. ‘Don’t you remember this? Being me, twenty years old, meeting – you?’
Her answer confused me. ‘It doesn’t work like that.’ She glared at me. ‘You do understand how come I’m stuck back in the past, staring at your zit-ridden face?’
‘No,’ I admitted reluctantly.
‘It was a Tolman manoeuvre.’ She searched my face. ‘Every faster-than-light starship is a time machine. Come on, ensign. That’s just special relativity! Even “Tolman” is the name of some long-dead pre-Extirpation scientist. They teach this stuff to four-year-olds.’
I shrugged. ‘You forget all that unless you want to become a navigator.’
‘With an attitude like that you have an ambition to be a captain?’
‘I don’t,’ I said slowly, ‘have an ambition to be a captain.’
That gave her pause. But she said, ‘The bottom line is that if you fight a war with FTL starships, time slips are always possible, and you have to anticipate them … Think of it this way. There is no universal now. Say it’s midnight here. We’re a light-minute from the Base. So what time is it in your fleapit barracks on 529? What if you could focus a telescope on a clock on the ground?’
I thought about it. It would take a minute for an image of the clock on the Base to reach me at lightspeed. So that would show a minute before midnight … ‘OK, but if you adjust for the time lag needed for signals to travel at lightspeed, you can construct a standard now – can’t you?’
‘If everybody was stationary, maybe. But suppose this creaky old Spline was moving at half lightspeed. Even you must have heard of time dilation. Our clocks would be slowed as seen from the base, and theirs would be slowed as seen from here. Think it through further. There could be a whole flotilla of ships out here, moving at different velocities, their timescales all different. They could never agree.
‘You get the point? Globally speaking there is no past and future. There are only events – like points on a huge graph, with axes marked space and time. That’s the way to think of it. The events swim around, like fish; and the further away they are the more they swim, from your point of view. So there is no one event on the Base, or on Earth, or anywhere else which can be mapped uniquely to your now. In fact there is a whole range of such events at distant places, moving at different speeds.
‘Because of that looseness, histories are ambiguous. A single location on Earth itself has a definite history, of course, and so does the Base. But Earth is maybe ten thousand light years from here. It’s pointless to map dates of specific events on Earth against Base dates; they can vary across a span of millennia. You can even have a history on Earth that runs backwards as seen from a moving ship.
‘Now do you see how faster-than-light screws things up? Causality is controlled by the speed of light. As long as light has time to travel from one event to another they can’t get out of order, from wherever they are viewed, and causality is preserved. But in a ship moving faster than light, you can hop around the spacetime graph at will. I took a FTL jaunt to the Fog. When I was there, from my point of view the history of the Base here was ambiguous over a scale of decades … When I came home I simply hopped back to an event before my departure.’
I nodded. ‘But it was just an accident. Right? This doesn’t always happen.’
‘It depends on the geometry. Fleeing the Xeelee, we happened to be travelling at a large fraction of lightspeed towards the Base when we initiated the hyperdrive. So, yes, it was an accident. But you can make Tolman manoeuvres deliberately. And during every operation we always drop Tolman probes: records, log copies, heading for the past.’
I did a double-take. ‘You’re telling me it’s a deliberate tactic of this war to send information to the past?’
‘Of course. If such a possibility’s there you have to take the opportunity. What better intelligence can there be? The Navy has always cooperated with this fully. In war you seek every advantage.’
‘But don’t the Xeelee do the same?’
‘Sure. But the trick is to try to stop them. The intermingling of past and future depends on relative velocities. We try to choreograph engagements so that we, not they, get the benefit. And of course they reciprocate.’ Dakk grinned wolfishly. ‘It’s a contest in clairvoyance. But we punch our weight.’
I tried to focus on what was important. ‘OK,’ I said. ‘Then give me a message from the future. Tell me how you crossed the chop line.’
She paced around the chamber, while the Spline’s weird hyperdrive muscles pulsed. ‘Before the fallback order came, we’d just taken a major hit. Do you know what that’s like? Your first reaction is sheer surprise that it has happened to you. Surprise, and disbelief, and resentment. And anger. The ship is alive; it’s part of your crew. And you live in it; it’s as if your home has been violated. So there was shock. But most of the crew went to defence posture and began to fulfil their duties, as per their training. There was no panic. Pandemonium, yes, but no panic.’
‘And in all this you decided to disobey the fallback order.’
She looked me in the eye. ‘I had to make an immediate decision. We had an opportunity; we were close enough to strike, I believed, and we were in a situation where my orders weren’t valid. So I believed. I decided to go ahead.
‘We went straight through the chop line and headed for the centre of the Xeelee concentration, bleeding from a dozen hits, starbreakers blazing. That’s how we fight the Xeelee, you see. They are smarter than us, and stronger. But we just come boiling out at them. They think we are vermin, so we fight like vermin.’
‘You launched the Sunrise.’
‘Hama was the pilot.’ My unborn, unconceived child. ‘He rode a monopole torpedo: the latest stuff. A Xeelee Sugar Lump is a fortress shaped like a cube, thousands of kilometres on a side, a world with edges and corners. We punched a hole in its wall like it was paper.
‘But we were taking a beating. Hit after hit.
‘We had to evacuate the outer decks. You should have seen the hull, human beings swarming like flies on a piece of garbage, scrambling this way and that, fleeing the detonations. They hung onto weapons mounts, stanchions, lifelines, anything. We fear the falling, you see. I think some of the crew feared that more than the Xeelee. The life pods got some of them. We lost hundreds … Her face worked, and she seemed to reach for happier memories. ‘You know why the name “Sunrise”? Because it’s a planet thing. The Xeelee are space dwellers. They don’t know day and night. Every dawn is ours, not theirs – one thing they can’t take away from us. Appropriate, don’t you think? And you should see what it’s like when a Sunrise pilot comes on board.’