The Big Bang, the concept of dark matter and finding out if the universe is expanding.

Imagine you could throw a ball straight up at 150 kilometres per hour. After a little over four seconds it will reach the peak of its trajectory, around 88 metres above the ground, and then start to fall back down.

This is what we would expect to happen. Something you would not expect is for the ball to continue accelerating after it left your hand, and vanishing into the clouds. This is why astronomers were very surprised to find that the expansion of our universe is not slowing; it is getting faster and faster. Just under 14 billion years ago our universe was extremely small, very hot and unbelievably dense. Then something made it start to expand. That event is often referred to as the Big Bang. As the young universe expanded, it became less dense and cooler, until galaxies and stars started to form. Since every piece of matter in the universe is exerting a gravitational attraction on all other pieces of matter, there is a force resisting the expansion, and which should be slowing it down.

Until very recently one of the big questions in astronomy was whether the expansion of the universe will continue for ever, or whether it would come to a stop and everything would start to fall back, leading to a Big Crunch sometime in the future. Is there enough matter in the universe to exert enough gravity to stop the expansion?

People counted stars, galaxies, gas clouds and so on, to see how much mass there is. The conclusion was that there is not enough material in the universe and that it will expand, slowing but never stopping. This logic and the conclusion it led to have been proved very wrong by more recent measurements. There is far more mass in the universe than we thought, most of it being Dark Matter, which we looked at last time. However, the expansion of the universe is accelerating, not slowing down. High School physics tells us that a thing will only accelerate if there is a force acting on it. In the universe we know of gravity pulling inwards, but for the expansion to accelerate there has to be a strong outward force. What is it?

The concept of Dark Matter was introduced as an extra factor to make the physics fit the observations. This is not satisfactory science and there are great efforts being made to get more solid evidence of its existence. In a similar way, the suggestion was made that the accelerating expansion of the universe is due to something called Dark Energy. As before, it makes the physics work, but what is it really? There are several theories being tested through additional observations. However, the most intriguing one dates back to the work of Albert Einstein.

When Einstein was trying to calculate what the universe is like, he kept getting one that is expanding or collapsing. However at the time scientists thought the universe was static. If a universe is static, it will immediately start to collapse under its own gravity.

To stop this from happening Einstein introduced an outward force, which he called the Cosmological Constant. He chose the force to be just strong enough to stop the collapse. Then, when the universe was discovered to be expanding, the need for Einsteinís outward force vanished. Then, in the 1990’s we found that not only is the universe expanding, it is doing so faster and faster. One proposal is to bring back Einsteinís outward force. Instead of making the force just strong enough to stop the collapse, we make it far stronger. This would cause the expansion of the universe to accelerate. Fortunately, today we know how to test this idea through independent means. We are doing experiments to see if this force exists. If it does, we’ll measure it and see if it is strong enough to explain how the universe is expanding. Otherwise we will need a different idea.

The western sky after sunset is dominated by Venus (lower and brightest) and Jupiter (higher and less bright). Saturn lies low in the southeast. The Moon will be Full on the 2nd.

Ken Tapping is an astronomer with the National Research Council’s Dominion Radio Astrophysical Observatory, Penticton.


Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

The Oliver Fire Department had to put out a fire on their own training ground, and it wasn’t one they set. (Facebook)
Vehicles torched at Oliver Fire Department training grounds

This suspected arson comes after the cars were vandalized earlier and suspicious fire the night before

Nuns of Mother Teresa’s Missionaries of Charity, carry some of her relics during a vigil of prayer in preparation for the canonization of Mother Teresa in the St. John in Latheran Basilica at the Vatican, Friday, Sept. 2, 2016. In which city did she do much of her charitable work? (AP Photo/Gregorio Borgia)
QUIZ: How much do you know about these motherhood issues?

In honour of Mother’s Day, take this 10-question quiz

Steven Brown is running for Penticton city council in the June by-election. (Contributed)
Penticton race director throws hat into city council ring

Steven Brown will run with a focus on small business

Penticton Vees celebrate a goal in their second win to start their season on Saturday night at the SOEC. (Brennan Phillips - Western News)
Penticton Vees head into final weekend tied for first in league

The Vees have two games to take the top spot

Kelsey Johnson, the City of Penticton’s manager for parks and recreation, was recognized by the Canadian Parks and Recreation Association as an emerging leader for her work. (Submitted)
National recognition for Penticton’s head of parks & rec

Kelsey Johnson was deemed an emerging leader by the Canadian Parks and Recreation Association

(The Canadian Press)
Trudeau won’t say whether Canada supports patent waiver for COVID-19 vaccines

‘Canada is at the table to help find a solution’

The body of Brenda Ware, 35, was found along Highway 93 in Kootenay National Park on Thursday, May 6, 2021. (RCMP handout)
RCMP ask for tips after woman’s body found in Kootenay National Park

Brenda Ware was found along Highway 93 in the park, 54 kilometres north of the town of Radium

People pass the red hearts on the COVID-19 Memorial Wall mourning those who have died, opposite the Houses of Parliament on the Embankment in London, Wednesday, April 7, 2021. On May 3, the British government announced that only one person had died of COVID-19 in the previous 24 hours. THE CANADIAN PRESS/AP-Kirsty Wigglesworth
For a view of a COVID-19 future, Canadians should look across the pond

Britain, like Canada, is one of the only countries in the world to delay second doses for several months

Edmonton Oilers’ Connor McDavid (97) celebrates his 100th point this season with Leon Draisaitl (29) against the Vancouver Canucks during second period NHL action in Edmonton on Saturday, May 8, 2021.THE CANADIAN PRESS/Jason Franson
Edmonton superstar McDavid hits 100-point mark as Oilers edge Canucks 4-3

NHL scoring leader needs just 53 games to reach century mark

City of Vernon Coun. Dalvir Nahal proposed two blocks of Main Street be closed to bolster recovery for downtown businesses amid the COVID-19 pandemic. (Caitlin Clow - Vernon Morning Star)
Vernon’s ‘support local’ Main Street closure would cost city $24K, staff say

Bylaw costs, loss of parking revenue and equipment logistics behind price tag

Five properties have been added to the Lake Country fire protection zone, after council moved to expand the local service area Tuesday, May 4, 2021. (Google Maps)
Lake Country expands fire protection zone, covering 5 exposed properties

The properties petitioned to join the local service area after being left out ‘for reasons unknown’

VSAR’s Air Rescue One unit assisted in a rescue in West Kelowna May 3, 2021. (VSAR screenshot)
VIDEO: VSAR’s Air Rescue One team assists in West Kelowna Rescue

The Vernon Search and Rescue helicopter team pulled off a successful rescue Monday

Peachland resident and cleanup volunteer Lloyd Stinson Sotas holds up a discarded TV riddled with bullet holes. (Aaron Hemens/Capital News)
PHOTOS: Peachland residents clean up community watershed

More than 70 people gave back to Mother Earth by assisting with the cleanup

Most Read