That’s a wonderful question. Assuming you mean outer space (or our universe), then the answer would have to be: we can’t. I’ll lead with an easy example of the scientific problem and how it pertains to your question.
In very general terms, the simplest way you or I can measure how big something is—and therefore find out where its boundaries are—is through observation, right? For example, look at a tennis ball and tell me what diameter it has using only your eyes. Assuming you can visualize how long one centimeter is, you’d be able to approximate the diameter of the tennis ball to within a reasonable measurement. Until you take out a ruler and actually measure it, however, you’ll be uncertain of its exact diameter, right?
The centimeter, in our example, is nothing more than a piece of information. In this case, the information we use is a unit of distance. When using solely our eyes to measure the diameter of the ball we use incomplete information since our eyes aren’t as exact as a calibrated ruler.
In terms of measuring the size of the universe in order to find where it ends or begins, our centimeter becomes a light year, and we have no ruler to pull out to tell us the exact diameter because light is always incomplete information in a sense. Therefore, we are always approximating the size of our universe based on incomplete information reaching our eyes or the technologies we use to substitute for our eyes (for things like cosmic microwave background radiation).
To expand on this: our observable universe, and therefore our approximation of its true size and boundaries, is limited by the information we receive via channels of information such as, but not limited to, light. A centimeter’s information, its distance, is technically set in stone. However, light is in a constant state of flux. Meaning: light is constantly reaching Earth from the farthest reaches of the Universe. Therefore the information we receive through light is always changing and is always incomplete. When our measuring stick is light, and not centimeters, we constantly have to change our answer, based on new incoming light (information), to the question of: how big is the universe?
That being said, the speed of light is pretty darn fast. It’s about 300 million meters per second or 670 million miles per hour! At that speed we could travel to the Sun in less than 9 minutes and to the Moon in less than 2 seconds. By comparison, it took about 4 days from launch to landing for the Apollo 11 astronauts to reach the Moon!
Regardless of how amazingly fast the speed of light is, we are unable to use its information unless it has reached Earth. Given the light information that has currently reached Earth from the absolute farthest reaches of our observable universe, we can estimate that that the diameter of our universe is about 93 billion light years. That comes out to a diameter of: 879,847,933,950,014,000,000,000,000 meters!
Unfortunately, when I say diameter, that implies to many that our universe is a sphere. And while since at least the time of Aristotle many people have assumed our Universe is round, the latest science shows that it’s most likely flat. Do you see how confusing this is? Not only can we not ascertain whether our universe is infinite, finite, has boundaries, or is boundless; we can’t even decide on a shape!
In addition, due to other issues, there will come a day when we’ll actually never be able to observe the entire universe “beyond the horizon”. Therefore, we’ll never be able to tell where space ends or begins, or how big the universe is, unless we employ technology or information other than light in order to do so.
Finally, there’s much more to measuring the size of the universe than to measuring a tennis ball; in addition to everything above we have to take into account: space, time, acceleration, expansion, orbits, volume, gravity, density, and many other certainties and uncertainties in order to come up with the right answer.
All this confusion and uncertainty has to do with our ever evolving understanding of math, physics, and our use of technology. As we progress and are able to better utilize all sorts of information, we may one day come up with an answer to your question in a more definitive form or number. As of right now we cannot be sure where, and if, the universe ends or begins in any one place nor what is beyond the horizon we can observe.
Answered by Artem Cheprasov
Every so often, physics gets sexy. The Big Bang and black holes regularly grab the headlines, and, more recently, something else has become the latest scientific superstar – the ‘God particle’. The search for this subatomic fleck has captured the public’s imagination unlike anything since Albert Einstein. But ask anyone what it actually is and you’re guaranteed a tumbleweed moment.
Enter Nicholas Mee, a particle physicist from Cambridge University. Higgs Force: The Symmetry-Breaking Force that Makes the World an Interesting Place, his first book, aims to do for the Higgs boson what Stephen Hawking did for the black hole. Higgs Force sets to bring particle physics to the masses, as A Brief History of Timetaught the world about space and time.
It’s a tall order. Modern physics is steeped in complex ideas and befuddling theories. If we’re honest, Stephen Hawking’s ten-million- copy-selling book sits unread on many bookshelves: few of us have managed to get past chapter nine. Realising this, Mee takes a different tack, opting to depict an historical narrative through a textbook format. Starting in ancient Greece, he charts the intriguing characters that have shaped our present understanding of the world. There’s no shirking on detail: perplexing logical puzzles are dotted throughout to keep the reader apace with the lofty concepts covered.
Higgs Force is a noble effort. Atoms, electrons and quarks are brought to life using metaphors and colourful language. Nevertheless, by page 100, non-academics may be scratching their heads, confused and feeling as if their head is in an isospin (physicist joke). Mee reassures the perplexed by quoting fellow physicist Richard Feynman:
“You think I’m going to explain it to you so you can understand it? You’re not going to be able to… My physics students don’t understand it either. That’s because I don’t understand [particle physics]. Nobody does.”
Higgs Force is a book that does not try to make you a physics expert, nor even particle physics competent. It offers a humble insight into a discipline that few people understand, equipping the reader with enough insight to explain the ‘God particle’ to impress friends. However, the book’s greatest strength is not in the science, but the vivid depictions of the story’s characters, who are as varied as the subatomic principles they discovered. Michael Faraday, the unschooled prodigy who invented the electric motor; Paul Dirac, the genius whose traumatic childhood left him virtually speechless; and Robert Wilson, the American artist-turned-physicist with the charisma to lead soldiers to war.
Higgs Force is an accomplished and engaging read. Be advised: it isn’t for the faint-hearted and a high-school physics education is a prerequisite. Lively biographies keep the pages turning in a way most popular science books fail to do. It reveals to the lay reader the importance of the Large Hadron Collider, the beauty of the natural laws and the riddle of Higgs. And it’ll likely be finished before that ageing copy of A Brief History of Time
Official Higgs Force website: www.higgsforce.co.uk
Congratulations to Pete Aighton, E. Parker and Alex Brown who were the winners of our Higgs Force book competition! You bagged yourselves a free copy, you lucky things…
The last few weeks have seen a spate of amazing images – from the outer edges of the solar system to as nearby as Alaska. Each image, while being visually amazing, represents incredible scientific research and potential discovery.
So, here are a pick of four incredible images from the past couple of months: a tour of the surfaces and skies of Mars, Earth, Saturn and the Milky Way itself.