Relevance: GS-I Origin of the Universe · GS-III Science & Technology (Space)

Source: MNRAS study, June 2026

1 · What happened

A new study (June 2026) confirms that our universe is growing faster and faster — its expansion is still accelerating. It was led by the University of Southampton (Dr Phil Wiseman) with Johns Hopkins University, and included Nobel laureate Adam Riess. It settles a recent scare. In 2025, a team from Yonsei University (South Korea) claimed the speeding-up may have stopped — blaming an “age effect” (the idea that older and younger exploding stars are not quite identical, fooling our measurements). The new team re-checked the data, found that the supposed flaw was not real, and confirmed the acceleration. The mysterious force behind it — dark energy — stands firm.

2 · Let’s start from the beginning: the Big Bang

About 13.8 billion years ago, everything — all space, matter and energy — was packed into an unimaginably tiny, hot point. In an instant it began expanding outward. This beginning is called the Big Bang.

Two simple ideas help here:

• It was not an explosion in space. It was the start of space itself stretching — and that stretching has never stopped.
• The balloon picture: imagine dots drawn on a balloon. As you blow it up, every dot drifts away from every other dot — not because the dots move, but because the rubber between them stretches. Galaxies are the dots; space is the stretching rubber.

The big surprise: for decades, scientists expected gravity (the pull between all matter) to slowly apply the brakes — like a ball thrown upward slows and falls back. But in 1998, careful measurements showed the opposite: the expansion is speeding up. Something unknown is pushing space apart. That “something” was named dark energy.

3 · What is the universe made of?

Here’s the humbling part: everything we can actually see is just a thin slice. Most of the universe is invisible.

27%

68%

• Ordinary matter — ~5%: stars, planets, gas, dust — everything we can see and touch.
• Dark matter — ~27%: invisible matter whose gravity pulls inward, acting like a glue that holds galaxies together. (We can’t see it, but we feel its pull.)
• Dark energy — ~68%: an unseen force that pushes outward, driving galaxies apart ever faster. It is the largest yet least understood part of the universe. Remember the contrast: dark matter pulls, dark energy pushes.

4 · How do we know? The “standard candle”

To measure such vast distances, astronomers needed a reliable “measuring stick.” They found one in a special kind of star explosion:

• A white dwarf is the small, dense, dead core left behind when a medium star (like our Sun) runs out of fuel.
• When such a star gathers a little extra matter and crosses a fixed mass point — the Chandrasekhar limit (about 1.4 times the Sun’s mass) — it explodes as a Type Ia supernova.
• Because they all explode at the same mass, they shine with almost the same true brightness every time.

The lighthouse trick: if every lighthouse used the same bulb, a dim one must be far away and a bright one must be near. Type Ia supernovae are those identical “lighthouses.” By comparing how bright they should be with how bright they look, astronomers work out their distance — and stitch together the universe’s growth story over billions of years.

This is exactly the tool that revealed the 1998 surprise — and the same tool the 2026 study used to confirm the acceleration is real. If the universe keeps speeding up forever, its likely far-future fate is a cold, dark, empty “Big Freeze.”

5 · Where India fits in

• AstroSat: India’s first multi-wavelength space observatory (by ISRO), carrying the Ultraviolet Imaging Telescope (UVIT) to study high-energy cosmic sources.
• Square Kilometre Array (SKA): India is a member of this global project to build the world’s largest radio telescope; its work is anchored at NCRA, Pune.
• Thirty Meter Telescope (TMT): India is a core partner in this giant optical telescope being built in Hawaii.
• Euclid (global): a European Space Agency telescope (with NASA) mapping how dark energy and dark matter shape the universe.

UPSC Value Box

Big Bang The start of the universe ~13.8 billion years ago, when space itself began expanding. Dark energy ~68% of the universe; an unseen force pushing space apart, driving accelerating expansion. Dark matter ~27%; invisible matter whose gravity pulls inward and binds galaxies (opposite of dark energy). Type Ia supernova Exploding white dwarf of uniform brightness; used as a “standard candle” to measure distance. Chandrasekhar limit The fixed mass (~1.4 × Sun) at which a white dwarf explodes — giving the uniform brightness. 1998 discovery Supernova data first showed expansion is accelerating (Nobel Prize, 2011). AstroSat India’s first multi-wavelength space observatory (ISRO); carries UVIT. SKA / TMT Square Kilometre Array (radio, NCRA Pune) & Thirty Meter Telescope (optical, Hawaii) — India is a partner in both. Big Freeze Likely far-future fate of an ever-accelerating universe — cold, dark and empty.

MCQ Practice Question

Q. With reference to the composition and study of the universe, consider the following statements: Ordinary (visible) matter makes up only about 5% of the universe’s mass-energy. Dark matter is the repulsive force that drives the accelerating expansion of the universe. Type Ia supernovae are used as “standard candles” to measure cosmic distances. Which of the statements given above is/are correct? (a) 1 and 2 only    (b) 2 and 3 only    (c) 1 and 3 only    (d) 1, 2 and 3

Answer: (c) 1 and 3 only Statement 1 — Correct: Ordinary matter is only ~5% of the universe. Statement 2 — Incorrect (the trap): The repulsive driver of acceleration is dark energy (~68%). Dark matter (~27%) does the opposite — its gravity pulls and binds galaxies together. Statement 3 — Correct: Type Ia supernovae, with their uniform brightness, serve as standard candles for measuring cosmic distances.