Health & Science

Boyle: “An’, as it blowed an’ blowed, I ofen looked up at the sky an’ assed meself the question — what is the stars, what is the stars?”

Joxer: “Ah, that’s the question, that’s the question — what is the stars?” Jose of us lucky enough to live far from the bright lights of cities can equate with Sean O’Casey’s characters in Juno and the Petcock if, out standing in a eld, we have often gazed up at the night sky.

On a clear night, you are rewarded with a breathtaking vision of stars — each one a distant sun. If you have a little knowledge (or a handy app), you might even be able to identify a constellation or two.

But the most awe-inspiring thing is that space seems to go on forever.So, what do we know, and what do we not know? Just how big is the Universe?

A static Universe

To begin with, we know two crucial facts. e rst is that the Universe began just shy of 14 billion years ago in a singular event, called the Big Bang. e second is that ordinary, visible light has a nite speed. It travels at the amazing rate of 300,000 kilometres (186,000 miles) a second, or fast enough to circle the Earth about seven times in a single second. We call the distance light can travel in a year a light-year, which is equal to about ten trillion kilometres (6 trillion miles).

Another important idea we need to understand is the difference between the visible Universe versus the entire Universe. e rst is what we can see, and the other is everything. is isn’t so hard to understand. Someone standing on the roof of the tallest building on the planet (the Burj Khalifa in Dubai) can see in every direction for about 100 km (60 miles). However, the surface of the Earth is much bigger than that, and the curvature of the planet makes it impossible to see everything.

If our Universe were static and unchanging (which isn’t true), the farthest thing we could see would be 14 billion light-years away. at’s because if an object that far away emitted light the moment the Universe began, that light would just now be arriving at Earth. Light emitted from an objected located 15 billion light-years away wouldn’t arrive here at Earth for another billion years, so we couldn’t see it yet.

In our hypothetical static Universe, the visible Universe would be a sphere, surrounding the Earth, with a radius of 14 billion light-years. e entire Universe might be bigger than that, but we would have no way of knowing, since light from more distant locations hasn’t arrived yet.

Our actual Universe

Of course, the Universe isn’t static, and that complicates things. e Universe began in the Big Bang, and that ‘bang’ caused the Universe to expand. As it travels, light has to ght against that expansion, which takes it longer to get to you.

To understand this, suppose a child stands ten metres away from you and rolls a ball toward you at two metres a second. It will take ve seconds for the ball to get to you. Now, suppose we have the same situation, with you standing on rm ground, but the child on one of those moving walking escalators you nd in airports. Suppose further that the walkway is moving away from you at one metre a second. Because of the motion of the walkway, the ball will not take ve seconds to get to you; it will take 10.

Alas, it gets more complicated. While the child was 10 metres away from you when they rolled the ball, because of the motion of the walkway, the child will be 20 metres away from you when the ball gets to you. e same thing has happened to the visible light from the Big Bang. at light travelled for 14 billion years to arrive at Earth now. And just like the child on the moving walkway, the current location of whatever emitted that earliest light isn’t 14 billion lightyears away; it’s now 46 billion light-years away. We see the light from where it was emitted, not where the emission source is now.

In this way, astronomers can say with con dence that the visible Universe — which is the sphere around the Earth out to the distance of the oldest thing we can see — is 92 billion light-years in diameter (that is, edge to edge).

So how big is the Universe?

But that is merely the visible Universe. What about the entire Universe? How can we know about parts that are so far away that we have not even seen them yet? at’s where things get interesting.

It may be surprising, but astronomers are not 100% sure they know the geometry of space. It could be at, or it could be curved. While space is three dimensional, we can use a two-dimensional analogy to understand what that means.

In two dimensions, at means at, like the surface of a table. However, a twodimensional surface could be curved, like the surface of a globe, but it also could be curved like the surface of a saddle. If it’s curved like the surface of a globe, that means if you had a super-fast spaceship and traveled long enough, you could end up back where you started, like a plane ying along the Earth’s equator.

Astronomers have studied the data and have determined that space is at, or nearly so. However, this determination is a measurement, and measurements have uncertainty. It remains possible that the Universe has a very tiny curvature. But if it is curved, then the equivalent of the ‘Universe’s equator’ is at least 500 times bigger than the visible Universe. Or possibly bigger than that.

So, despite not knowing the size of the entire Universe, astronomers know that it is at least 500 times larger than what we can see. ( at number represents the distance one would have to travel to return to your starting location.) In the same way that the volume of a cube is the distance along the sides cubed, the volume of the entire Universe is, at a minimum, 125 million times bigger than the visible Universe.

What would Joxer have to say?

There is very positive news for the thousands of men with prostate cancer who medics in the UK say could be cured through a simple but innovative hour-long operation.

The ‘game-changing’ treatment uses electrical currents to destroy difficult to reach tumours. The one-hour ‘Nanoknife’ operation has been described as ‘amazingly simple and quick’ by surgeons.

It uses a technique called irreversible electroporation to administer electrical pulses into the tumour, cutting open the membrane of the cells in a far less invasive manner than standard treatments, meaning there are fewer risks to surrounding organs and tissues.

The introduction of the therapy on the NHS comes as more than 50,000 cases of prostate cancer are detected ment, consultant urologist Professor Mark Emberton said: ‘This offers us a new class of therapy – it’s a completely new way of destroying cells. The beauty of it is that it’s such a simple technique to train surgeons in. That makes it a gamechanger.”

Mr Emberton has said that Nanoknife has the potential to become a standard treatment for prostate cancer as opposed to having it only available in major specialist centres, as is currently the case with targeted treatments. “At times like this, when the NHS is under great pressure, day surgery avoids the need for overnight stays in hospital and means that we can use our operating theatres more efficiently,” the professor said.

Guided by MRI scanning, the short pulses can be targeted to the right area, and surrounding healthy cells are left untouched and preserved, experts said.

Natalia Norori, the knowledge manager at Prostate Cancer UK, said: “Early studies suggest that treatments like Nanoknife could effectively treat prostate cancer while also reducing side-effects for men. This technology is one of many types of focal therapy on the horizon, which are designed to target the tumour more precisely and limit damage to the rest of the prostate.”

This could make a big difference to the quality of life of men and it now needs to be tested in much larger trials to see whether it is as effective as traditional treatments.

Senior medics in Ireland are keeping a close eye on developments.