This is a

CBS I in the world. I'm John Bachelor with Govered Schilling and his wonderful new book is a search for something that we haven't found.

But the search continues. And one of the ways

the search is, well if it's not small, what if it's massive? What if it's massive

complex halo object, macho. What if gravitational lending,

lensing can give us a result that we haven't been able to find

because we were looking for something small?

As far as I can see right now there are teams who

exhausted themselves in the late 20th century. Has macho now been retired or

is...

Absolutely, absolutely, but it's a very nice story because it's a very neat story to explain how science works.

Back in the 1980s, everybody thought dark matter must be this non-barionic, cold dark matter,

weekly interacting, massive particle, and that's where the physicists started to work on.

And they had all these theories and they tried to look for it.

But then in science you always have to think, yes, but what if?

What if dark matter is actually something else?

Or what if dark matter is actually something else or what if dark matter might be these wind particles

but there might be other types of dark matter too. We can't exclude it. So we need to look for other types of dark method too. You need to be sure that some other explanation cannot be the whole or part of the of the truth.

So what they started to do was looking through this gravitational lensing at the existence of of

dark massive objects in the outer parts of galaxies.

And the only way you can do that is by looking at the way such a dark invisible object would bend and

amplify the light of an individual star. And it's a very rare event. So if you want to be successful in that you have to study hundreds of

...