What is dark energy? Write 1-2 paragraphs.

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Explanation:

Dark Energy, Dark Matter

In the early 1990s, one thing was fairly certain about the expansion of the universe. It might have enough energy density to stop its expansion and recollapse, it might have so little energy density that it would never stop expanding, but gravity was certain to slow the expansion as time went on. Granted, the slowing had not been observed, but, theoretically, the universe had to slow. The universe is full of matter and the attractive force of gravity pulls all matter together. Then came 1998 and the Hubble Space Telescope (HST) observations of very distant supernovae that showed that, a long time ago, the universe was actually expanding more slowly than it is today. So the expansion of the universe has not been slowing due to gravity, as everyone thought, it has been accelerating. No one expected this, no one knew how to explain it. But something was causing it.

Eventually theorists came up with three sorts of explanations. Maybe it was a result of a long-discarded version of Einstein's theory of gravity, one that contained what was called a "cosmological constant." Maybe there was some strange kind of energy-fluid that filled space. Maybe there is something wrong with Einstein's theory of gravity and a new theory could include some kind of field that creates this cosmic acceleration. Theorists still don't know what the correct explanation is, but they have given the solution a name. It is called dark energy.

What Is Dark Energy?

More is unknown than is known. We know how much dark energy there is because we know how it affects the universe's expansion. Other than that, it is a complete mystery. But it is an important mystery. It turns out that roughly 68% of the universe is dark energy. Dark matter makes up about 27%. The rest - everything on Earth, everything ever observed with all of our instruments, all normal matter - adds up to less than 5% of the universe. Come to think of it, maybe it shouldn't be called "normal" matter at all, since it is such a small fraction of the universe.

Changes in the Rate of Expansion over Time

In physical cosmology and astronomy, dark energy is an unknown form of energy that affects the universe on the largest scales. Dark energy is the name given to the mysterious force that's causing the rate of expansion of our universe to accelerate over time.physical cosmology and astronomy, dark energy is an unknown form of energy that affects the universe on the largest scales.

Dark Energy is a hypothetical form of energy that exerts a negative, repulsive pressure, behaving like the opposite of gravity. ... Dark Energy makes up 72% of the total mass-energy density of the universe. The other dominant contributor is Dark Matter, and a small amount is due to atoms or baryonic matter.

Dark energy is the name given to the mysterious force that's causing the rate of expansion of our universe to accelerate over time, rather than to slow down. That's contrary to what one might expect from a universe that began in a Big Bang.

dark energy doesn't actually exist, and is merely a measurement artifact. For example, if we are located in an emptier-than-average region of space, the observed cosmic expansion rate could be mistaken for a variation in time, or acceleration.

Dark energy is the name given to an unexplained force that is drawing galaxies away from each other, against the pull of gravity, at an accelerated pace. Dark energy is a bit like anti-gravity. Where gravity pulls things together at the more local level, dark energy tugs them apart on the grander scale.

Explanation:

the backbone of the dna and rna compound is sugar phosphate.

after a the power stroke, adp is released, but the cross-bridge formed is still in place. atp then binds to myosin, moving the myosin to its high-energy state, releasing the myosin head from the actin active site.