BBC Focus - 09.2019

Q&A

DEAR DOCTOR...

DELICATE ISSUES DEALT WITH

BY SCIENCE FOCUS EXPERTS

DOI REALLYNEEDTOLEAVE

MYFOODTOSTANDAFTERIT

COMESOUTOFTHE

MICROWAVE?

Microwaves only penetrate to a depth of around
three or four centimetres, so anything deeper is
heated indirectly, by conduction from the outer
layers of food. The cooking instructions on a ready
meal might say to heat it on full power for five
minutes and then leave to stand for another two. The
first phase adds enough energy to cook your lasagne,
but when it comes out of the microwave, that energy
is unevenly distributed. Leaving it to stand allows the
heat to make it to the centre, where it will kill o any
bacteria. So always respect the instructions. LV

It may seem that way, but

rest assured, it’s probably

not that they don’t care,

and it’s probably not all

down to jealousy, either.

It’s likely that they just

find it diicult to fully

appreciate what an

awesome time you had.

Psychologists at

Harvard University have

been studying the social

dynamics that play out

when we share stories.

They’ve found that most

of us (storytellers and

listeners alike) think that

it will be more

pleasurable for all

involved to hear stories

of extraordinary

experiences rather than

more mundane tales. Yet

the converse tends to be

true – it’s actually more

rewarding to share stories

that everyone finds

familiar. A key reason is

that it’s such a challenge

to convey exciting or

unusual experiences in

words. Your head may be

filled with memories of

astonishing views or

hilarious nights out, but

unless you’re a gied

raconteur, when you try

to articulate those

experiences, your

audience is likely to be le

cold. So, paradoxically,

the more remarkable your

summer escape, the more

you risk alienating your

audience. By contrast, if

you went somewhere

familiar and did what

many others in your social

group do, your colleagues

will probably enjoy

hearing about your

holiday more, as they’ll be

able to chip in with their

own anecdotes. CJ

WHY DOES NO ONE AT WORK

CARE ABOUT MY LOVELY

SUMMER HOLIDAY?

I TOOK ONE OF MY WIFE’S

CONTRACEPTIVE PILLS AS A

DARE, BUT NOW I’M WORRIED.

WILLANYTHINGHAPPEN?

Nothing will happen if you only took one. There’s a
one in four chance that the pill was a dummy anyway,
as most packets include seven tablets with no drugs
in them (meant to maintain the habit of taking the
pill while the ‘withdrawal bleed’ happens). If you
regularly took the ‘combined pill’, which contains
oestrogen and progestogen hormones, it would have
mild feminising eects, such as wider hips, soer skin
and slight breast development. The oestrogen dose is
about a tenth of that taken by transgender women,
but it’s a form of oestrogen associated with higher
risks of deep vein thrombosis, so it wouldn’t be a
good idea for anyone wanting to transition. Regularly
taking a progestogen-only pill would have the main
impact of reducing your sperm count and libido. HG

DAVID KELLY,

MANCHESTER

DO OBJECTS

IN THE

UNIVERSE

MOVING

TOWARDS

US SHOW A

BLUE SHIFT?

The wavelength of

light emied by an

object is changed by

its motion relative to

an observer. An object

moving away from us

is ‘redshied’ – that is,

its light is shied

towards the longer

wavelengths at the

red end of the visible

spectrum. But

although the Universe

is expanding, not all

objects are redshied.

Some of the nearest

stars, such as

Barnard’s Star, are

moving towards us

and hence show a

‘blueshi’ (their light

is shied towards

shorter wavelengths).

Even some galaxies

(for example, the

Andromeda Galaxy)

are blueshied. This is

because, over

relatively short

distances, the local

gravitational

araction between

galaxies can

overcome the general

expansion of the

Universe. The highest

blueshi yet recorded

is actually from a

group of stars called a

‘globular cluster’

that’s whizzing

towards us at

1,026km/s. But

fear not – it is still

millions of light-years

away! AGu