Turns
out that it is the definition of zero which explains the situation. An
amplifier is designed to produce a certain level of amplification and that is
defined as 0dB, you then turn down the amplification to suit your needs. So
that means my amplifier must be bigger than his!
This
got me thinking about other places where negative numbers make things
confusing. I used to work with a man who use to talk about getting a negative
interchange on his way to work on the train. Unless he’d invented a time
machine or was a friend of Dr Who how could that be possible?
If
your train arrives at an interchange point at 12 o’clock and your onward train
has already left (11:50) then you will have to wait for the next one (12:07),
however, if the first train is 10 minutes or more late you can get that one.
Voila you’ve just made a -10min interchange.
It
doesn’t just work for interchanges it works for any train. I typically arrive
at the station at 7:05 for a departure at 7:18 (I don’t like being late – what if
it takes me longer to cross the road than usual?) but if the 7:03 train is
running just a few minutes late I can get on that train instead. I only travel
on the train once a week and it’s surprising how often this happens (or maybe
not that surprising when you realise I’m travelling on the UK rail network).
Delays
are not uncommon on my way home from work either. I often arrive at the station
and hear an announcement that all trains are running 30 minutes late because of
an earlier incident (signal failure or body on the line usually).
On
the face of it this sounds terrible, I’m going to have to stand on a wet and
windy platform for an additional 30 minutes (they’ve taken away the cosy
waiting room and replaced it with a smaller, one man version for the station
guard) but unless the earlier incident happened in the last 30 minutes it will
have little effect on my waiting time.
There
are 3 trains per hour, one every 20 minutes, so if you add 30 minutes to all of
them all you have done is move them out of phase by 10 minutes. If there were
only 2 trains per hour you wouldn’t notice any difference at all.
Trains
don’t use radar to work out where they and other trains are but if they did
they would implement an extremely confusing use of negative numbers – imaginary
numbers.
I’ve
read numerous popular science books which have contained a chapter on imaginary
numbers and I still can’t get my head around the concept.
An
imaginary number is defined as:
and
apparently they make doing calculations with waves and phases much easier – by
easier I think what they mean is quicker for a computer to calculate not easier
for a person to understand.
The clocks went back last weekend (i.e. we added -1 hours) so does that mean it will be lighter or darker when I get up for work
in the morning?
