DARK
ENERGY SPECTROSCOPIC INSTRUMENT - ECONOMY
News:
What a new 3-D map of
universe hints about the nature of dark energy
What's
in the news?
●
Recent findings from the Dark Energy
Spectroscopic Instrument (DESI) highlight the expansion of the universe at a
rate of 68.5 km/s per megaparsec and the significant roles of dark matter and
energy.
Dark
Energy Spectroscopic Instrument (DESI):
●
DESI has produced the largest ever 3D map of the universe to study dark energy's effects over
the past 11 billion years, achieving a precision better than 1% for the first
time.
●
The leading model, Lambda CDM, incorporates both cold dark matter (CDM) and dark
energy (Lambda), where matter and dark matter slow down expansion, whereas dark
energy accelerates it.
Location:
●
DESI, located on the Mayall 4-meter
telescope at Kitt Peak National
Observatory, US, is a collaborative effort of over 70 institutions
worldwide, including those from India, measuring the impact of dark energy on
universe expansion.
Joint
Collaboration:
●
DESI is a collaboration of more than 900 researchers in institutions across
the world.
●
From India, TIFR is the only participating institution.
Key
Findings From Observations:
1.
Preparation of Detailed Map of Universe:
●
Using Dark Energy Spectroscopic Instrument
(DESI) researchers have been able to measure
light from six million galaxies to prepare the most detailed map of the
universe yet with very precise information about the distances between
these galaxies.
○
The distances between these galaxies have
been measured with a very high degree of accuracy. Thus, it is called a
three-dimensional map.
●
Knowing the precise distances of the
galaxies is crucial because that allows us to calculate the expansion rate of
the universe.
2.
Mapping of the Distribution and Movement of these Galaxies:
●
The precise distances calculated have
resulted in the mapping of the distribution and movement of these galaxies over
time.
●
This has been done by comparing the data with similar data for some of the galaxies
obtained through other experiments.
3.
Measurement of the Expansion Rate of the Universe:
●
The dark energy spectroscopic instrument
collaboration has measured that the expansion
rate of the universe was increasing by 68.5 km per second after every 3.26
million light years of distance, defined as megaparsec.
●
Through these precise measurements, the
scientists have found that some of the calculated values are not consistent
with current well-established theoretical models, which otherwise describe the
universe very well.
4.
Change in Energy Density:
●
The results from dark energy spectroscopic
instruments suggest that there are changes in energy density in contrast to the
theoretical models.
○
The theoretical models suggest that the
energy density of dark energy, or the amount of dark energy contained in any
volume of space, remains constant even under expansion.
●
In these theoretical models, a change in
energy density would make the universe unstable.
Go
back to basics:
Dark
Energy:
●
Dark energy is the mysterious force that is believed to be causing the universe to expand uncontrollably.
Expanding
Universe:
●
The hypothesis comes mainly from the
observed phenomenon of the universe
expanding at a rapid rate.
●
The vast empty spaces between stars and
galaxies have been measured to be expanding at an accelerating pace, despite
the countervailing force of gravitation that has the effect of pulling things
together.
●
Scientists have been unable to find any
explanation for this rapid expansion, and have been forced to hypothesize that
there must be some “dark” energy causing this expansion.
Significance:
●
Understanding the nature of dark energy
can offer key insights into the origin and evolution of the universe, as well
as its eventual fate.
●
It can reveal new fundamental forces at
work, and could unravel our entire knowledge of the physical world.
Dark
Energy vs Dark Matter:
1.
Composition of the Universe:
●
Dark energy accounts for roughly 68
percent of the universe’s total mass and energy.
●
Dark matter makes up 27 percent.
●
The rest i.e., around 5 percent is all the
regular matter we see and interact with every day.
2.
Dark Matter:
●
It makes up most of the mass of galaxies
and galaxy clusters, and is responsible for the way galaxies are organized on
grand scales.
3.
Dark Energy:
●
It is the mysterious influence driving the
accelerated expansion of the universe.
●
While dark matter attracts and holds
galaxies together, dark energy repels and causes the expansion of our universe.
4.
Interaction with Gravity:
●
Dark
matter does interact with gravity, but it doesn’t reflect, absorb, or emit
light.
●
On the other hand, dark energy is a repulsive force — a sort of anti-gravity that
drives the universe’s ever-accelerating expansion.