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Einstein's theory of relativity is 100 years old. Shutterstock/Bangkokhappiness

What is the theory of relativity all about?

This is the century-old theory that has given us concepts like black holes and the big bang, writes Dr Cormac O’Raifeartaigh.

Today marks the beginning of Science Week and for 100 years Einstein’s theory of relativity has been a pillar of modern physics. You’ve probably heard of it, but aren’t sure what the hell it means. Here is physicist Dr Cormac O’Raifeartaig’s super-painless guide to the theory that conquered the universe.

1. What’s the big deal?

2016 marks the centenary of one of the greatest breakthroughs in modern science, Einstein’s general theory of relativity. This is the theory that has given us concepts like black holes, time warps and the big bang.

2. Is it all just theory?

No, as the 20th century progressed, more and more evidence emerged in support of the theory, even its strangest predictions.

3. Can you give us a basic idea of relativity?

Students are always surprised to discover that there are actually two theories of relativity. In the first, the special theory of relativity, Einstein suggested that time and distance are not the same for all; an observer in motion relative to an object will measure the length of the object differently from an observer at rest relative to the object. Even stranger, the observer in motion will measure time differently from an observer at rest. The theory seemed strange at first, but experimental evidence soon emerged to support it.

shutterstock_173695178 E=mc2 changed our understanding of our world. Shutterstock / Fernando Batista Shutterstock / Fernando Batista / Fernando Batista

4. And the second theory?

In 1916, Einstein published the general theory of relativity, a theory that predicted that space and time could be distorted by mass. In Einstein’s theory the sun doesn’t pull on the earth – the mass of the sun distorts the space around it, and the earth travels through that curved space. The theory also led to the prediction of strange phenomena such as black holes and the big bang. Strangest of all, time could be affected by gravity!

5. What is a black hole exactly?

In a black hole, a huge concentration of matter in a small amount of space warps the surrounding space so severely that the space curls back on itself so that nothing can escape – not even light.

6. Is there any evidence to support the general theory?

Yes. In 1919, British astronomers measured a bending of distant starlight by our sun, confirming a warping of space by the sun’s mass. Since then, many other effects have been measured, such as the discovery of a giant black hole in the centre of our galaxy.

7. Wasn’t there some big news on black holes recently?

Yes, last year saw the first detection of gravitational waves, a prediction of the theory. The waves are thought to emanate from the collision of two black holes a billion light years away.

8. I don’t suppose all this has any technological application?

Actually, GPS depends critically on general relativity. Because relativity predicts that gravity affects time, the satellite clocks have to be adjusted to take account of the fact that they are in a weaker gravitational field than earthbound clocks in order to the two sets of clocks. Without this correction, GPS would not work.

9. Where does the big bang come into the story?

General relativity predicts that our universe cannot be static, but must expand or contract. Astronomical evidence suggests that the universe has been expanding and cooling for billions of years, from an initial state that was much smaller and hotter – known as the big bang.

Galaxy Einstein connected the mass of an object with its energy and heralded a new world. Shutterstock / PlanilAstro Shutterstock / PlanilAstro / PlanilAstro

10. Didn’t I hear that relativity has been disproven?

Newspapers love to publish ‘refutations’ of relativity from diverse commentators. Relativity scepticism is so common that most science journals and magazines have long since stopped accepting submissions on the topic. ‘Einstein wrong’ is a great story but amateur commentators usually ignore the vast body of supporting evidence for the theory.

11. What do you think causes scepticism about relativity?

Relativity scepticism is interesting because the theory is not in conflict with religious dogma, political worldviews or vested interests. I suspect the scepticism stems from the fact that relativity makes predictions that seem to conflict with our everyday ‘common sense’ experience of the world, while the supporting evidence is locked away in the rather inaccessible world of particle physics and cosmology. As Einstein himself once remarked, “Common sense is a collection of prejudices acquired by age 18.”

The Science Week talk on Einstein is on at 8pm tonight (November 14) in the Ed Burke Theatre in Trinity College Dublin and is open to the general public.

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62 Comments
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    Mute Bernard A Kavanagh
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    Mar 14th 2022, 1:03 PM

    And this all happened under FG FF when in power for the last 99 years! They have morally destroyed this country. But the Irish have short memories and keep voting them back into POWER!

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    Mute Mike Dunne
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    Mar 14th 2022, 2:32 PM

    @Bernard A Kavanagh: There isn’t much to choose from. Sinn Fein have been supporting the coalition since day one. All very depressing.

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    Mute Bernard A Kavanagh
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    Mar 14th 2022, 3:02 PM

    @Mike Dunne: That’s a poor argument.

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    Mute Just Some Guy
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    Mar 14th 2022, 3:47 PM

    @Bernard A Kavanagh:

    Fine Gael haven’t been in Government for 99 years. Fianna Fail bankrupted this country when we needed a bailout. Also these illegal adoptions happened when Fianna Fail were in charge. Society allowed this to happen

    Sinn Fein are angels are they? David Cullinane who shouted up the Ira when he got elected.

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    Mute Bernard A Kavanagh
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    Mar 14th 2022, 5:42 PM

    @Just Some Guy: I never said FG have been in power for 99 years. I said FG and FF have been in power for 99 years.

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    Mute David Dineen
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    Mar 14th 2022, 1:48 PM

    When i went to find my brother i discovered alot, so much so the church were taking me to court, the amount of illegal adoptions are huge, wait till they discover the thousands sent away…

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    Mute Aidan Bergin
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    Mar 14th 2022, 1:55 PM

    @David Dineen: taking you to court for what?

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    Mute John Long
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    Mar 14th 2022, 1:59 PM

    €3000 isn’t a fraction for these people deserve.

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    Mute Olive Whyte
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    Mar 14th 2022, 2:06 PM

    Is there a few zeros missing on that figure??. €3,000 is an insult.

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    Mute Darren Byrne
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    Mar 14th 2022, 3:13 PM

    @Olive Whyte: didn’t read the article then, no. Quelle surprise. The 3000 is to cover the cost of initial DNA tests and legal consultation, it’s not compensation.

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    Mute Olive Whyte
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    Mar 14th 2022, 3:38 PM

    @Darren Byrne: did I mention the word compensation??? No need to be rude to a complete stranger.

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    Mute Denis Ryan
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    Mar 14th 2022, 4:34 PM

    @Olive Whyte: He is only being rude to someone who didn’t read the article but needed to do some virtue signaling. You assumed the €3000 was compensation hence the line about missing zeros.

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    Mute Jane Osman
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    Mar 14th 2022, 4:42 PM

    @Denis Ryan: No she didn’t, read it again (it’s very, very short)

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    Mute Denis Ryan
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    Mar 14th 2022, 4:46 PM

    @Jane Osman: very good Jane, I said she assumed and now she is backtracking at a rate of knots.

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    Mute joe oneill
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    Mar 14th 2022, 1:36 PM

    Magdalene laundries,mother and baby homes,illegal adoption’s….the lies and cover ups continue,the UN Commission
    On Civil Rights needs to come in and do a no holes barred investigation in order for folks to get the proper justice and compensation that they deserve.If people in authority, government don’t want to cooperate jail them.

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    Mute Stephen Carslake
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    Mar 14th 2022, 3:01 PM

    It is very hard to believe that the people in ireland vote these politiicans in every 5 years or so to represent us the people and once they get in all they do is turn their backs on the very people who put them in power for at least four and a half yeats.
    Time to wake up and stop voting the same 2 parties in every year and this €3000 euro offer is for expenses not even for the suffering.
    The only ones suffering now is the voters just ask where is our government now ? ALL ON JUNKET TRIPS at our expense country is a 3rd world country again thanks to the 2 parties forever voted in.

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    Mute Aidan Dorney
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    Mar 14th 2022, 3:14 PM

    @Stephen Carslake: I agree with you, Stephen. May I say Stephen manning from integrity Ireland has coined the perfect name for them. He calls them the diabolical’s

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    Mute Roger Bond
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    Mar 14th 2022, 7:12 PM

    @Stephen Carslake: If the other party is going to give out money for everything that happened many decades ago then we will be bankrupt again.
    People need to know that attitudes were different then in every country in the world.
    We are unique in always looking back and our compensation culture is unique too.

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    Mute John Kavanagh
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    Mar 14th 2022, 2:25 PM

    I always thought knowing who you are is priceless.. but obviously it’s only worth 3k

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    Mute Jane Osman
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    Mar 14th 2022, 4:44 PM

    @John Kavanagh: Well said friend!

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    Mute Nichola Corcoran
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    Mar 14th 2022, 2:30 PM

    Wow 3,000 euro compensation for being sold at birth. They deserve so much more, shame on this government if they think that is appropriate.

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    Mute Disco Inferno
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    Mar 14th 2022, 6:07 PM

    @Nichola Corcoran: it’s not compensation, read the article

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    Mute Marg FitzGerald
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    Mar 14th 2022, 7:07 PM

    @Nichola Corcoran: it’s not compensation

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    Mute Ciaran Dunne
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    Mar 14th 2022, 3:58 PM

    What about a criminal prosecution in every proven case of fraud against St Patrick’s Guild . Or is the €3000 hush money ?

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    Mute Aidan Dorney
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    Mar 14th 2022, 2:32 PM

    3k is a joke & the state should be held to account 3k? Just dealt with a gentleman looking up his records for his wife for health reasons. If the entries were incorrect well they were up the river without a paddle to put it nicely. 3k does not cut it.

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    Mute Gerrard
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    Mar 14th 2022, 5:12 PM

    Give them all 1 million each sure we have loads of money to hand out

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    Mute Roger Bond
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    Mar 14th 2022, 7:05 PM

    Compensation should be sought from the families who forced these adoptions on the mother because the families were not brave enough to accept a child from an unmarried mother.

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    Mute Mike Dunne
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    Mar 14th 2022, 2:33 PM

    This sounds like a bad Irish joke, except it’s not funny for those directly involved.

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    Mute Ciaran Dunne
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    Mar 14th 2022, 8:30 PM

    God forgive the poor eejit that though this €3000 was an appeasement for their scandalous treatment by this government!

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