BBC Focus - 09.2019

Q&A

GETTY IMAGES X8, ALAMY ILLUSTRATIONS: DAN BRIGHT

This apparently simple question impinges on a

fundamental axiom of physics: that there is no

universal reference frame. So, when talking

about the motion of the Earth, we have to

declare which object the motion is with respect

to. For example, at the Earth’s equator you travel

approximately 40,000km a day with respect to

the Earth’s centre. Each day, the Earth’s orbit

takes you about 2.5 million kilometres with

respect to the Sun’s centre. And each day, the

Earth moves about 19 million kilometres with

respect to the centre of the Milky Way. Finally,

the Earth is also travelling about 47 million

kilometres per day with respect to the ‘cosmic

microwave background’ (CMB) – the leover

radiation from the birth of the Universe – which

is perhaps the best surrogate we have for a

universal reference frame. Since the directions of

all these velocities are always changing, it would

be meaningless to add them together. AGu

CHARLES

DARWIN AND

CHEWBACCA?

WHAT CONNECTS

3. Badgers have a complex vocal
   repertoire of at least 16 dierent calls,
   ranging from low growls and grunts, to
   chiers, squeaks, yelps and even a sort of
   quacking sound.


4. When Ben Bur,
   sound designeron
   the original Star
   Wars movies,
   developed thevoice
   of Chewbacca,he
   used recordingsof
   badger calls, aswell
   as bears, lionsand
   a walrus.


5. Earthworms are the staple food of
   badgers, making up to 80 per cent of their
   diet. Earthworms aren’t very nutritious,
   though, so a single badger can eat several
   hundred of them in a night.

Tomatoes from the fridge rarely fail

to disappoint. Refrigeration does

extend their shelf life by slowing the

ripening process, but it also

dramatically reduces levels of avour

and fragrance chemicals known

as ‘volatiles’.

A 2016 US study found that chilling

tomatoes for a week reduced the

activity of genes that code for

enzymes needed to synthesise these

volatiles, which are responsible for

giving tomatoes a sweeter, more

complex taste. ED

I , I I

WHY SHOULDN’T

YOU PUT TOMATOES

IN THE FRIDGE?

STEPHEN NEWMAN, FOLEY, ALABAMA

HOW FAR DO WE TRAVEL THROUGH SPACE EVERY DAY?

1. Although most famous for his work on
   evolution, Charles Darwin’s final
   scientific book was about earthworms. It
   sold more quickly in its first year than
   On The Origin Of Species!

IAIN TODD, BRISTOL

WHY DO I PRODUCE SO MUCH

SALIVA WHEN I GO FOR A RUN?

The various studies that have looked at this actually

show conicting results. It seems that a short jog in

cold weather results in more saliva, while a marathon

on a warm day actually reduces saliva production.

Your body may initially be trying to oset the drying

eect of the extra mouth breathing, but over longer

periods dehydration sets in and your body reduces

saliva production to conserve water. All exercise,

regardless of the intensity, also makes you secrete

more of a protein called MUC5B. This makes your

saliva more sticky and viscous, which contributes to

that dry mouth feeling you can get aer exercising. LV