This week, what puts the brakes on the growth of galaxies?

It was essentially a very big question mark, how the black hole, which is powerful, is extremely powerful,

but so tiny and compact, can affect the whole galaxy.

And the scientists whose business ideas are getting a grilling.

Really, I have to admit at this point, I don't know what you do, and I don't know why it's important.

Plus the ice that could be in all of our cells.

This is the nature podcast. I'm Jeff Marsh.

And I'm Kerry Smith.

Mary, Mary, quite contrary, how does your galaxy grow?

Not as much as we would expect, it seems.

In simulations, galaxies form many more stars than we see in the real universe.

Something must be stopping stars from developing.

The culprits might be supermassive black holes.

They lurk at the centre of every galaxy,

and when they're active, they produce crazy powerful winds

that could blow star-forming gas clean out of the galaxy.

But seeing the process in action is difficult.

Black holes are powerful, all right, but they're tiny compared to their galaxy, and the winds obscure the black hole.

Physicists have seen either the black hole or a sea of gas exiting the galaxy, but not the two together.

Now a group of astrophysicists have caught a black hole red-handed.

Francesco Tom Bezi, an astrophysicist at NASA's Goddard Space Flight Center,

explained their findings to reporter Lizzie Gibney.

...