New Way to Measure Dark Energy

Researchers have discovered a method to potentially detect and measure dark energy by examining the motion between the Milky Way and Andromeda galaxies. This technique, still in its early stages, can estimate the upper value of the cosmological constant, a simple model of dark energy, which is five times higher than values determined from the early universe.




Researchers from the University of Cambridge have discovered a new way to measure dark energy – the mysterious force that makes up more than two-thirds of the universe and is responsible for its accelerating expansion – in our own cosmic backyard.

The researchers found that it may be possible to detect and measure dark energy by studying Andromeda, our galactic next-door neighbor that is on a slow-motion collision course with the Milky Way.


Since it was first identified in the late 1990s, scientists have used very distant galaxies to study dark energy but have yet to directly detect it. 

However, the Cambridge researchers found that by studying how Andromeda and the Milky Way are moving toward each other given their collective mass, they could place an upper limit on the value of the cosmological constant, which is the simplest model of dark energy. 

The upper limit they found is five times higher than the value of the cosmological constant that can be detected from the early universe.

Although the technique is still early in its development, the researchers say that it could be possible to detect dark energy by studying our own cosmic neighborhood. The results are reported in The Astrophysical Journal Letters.

Everything we can see in our world and in the skies – from tiny insects to massive galaxies – makes up just five percent of the observable universe. 

The rest is dark: scientists believe that about 27% of the universe is made of dark matter, which holds objects together, while 68% is dark energy, which pushes objects apart.  READ MORE...

FIFTH Fundamental Force of Nature

Quarks and antiquarks, which interact with the strong nuclear force, have color charges that correspond to red, green, and blue (for the quarks) and cyan, magenta, and yellow (for the antiquarks). Any colorless combination, of either red + green + blue, cyan + yellow + magenta, or the appropriate color/anticolor combination, is permitted under the rules of the strong force. If new phenomena appear in these well-studied systems, they could be indicative of a new fundamental force beyond the known four.



Back in the late 1800s, only two forces, electromagnetism and gravity, were thought to describe all of the interactions that occurred in the Universe.

Over the 20th century, new phenomena resulted in the discovery of two more fundamental forces: the strong and weak nuclear forces, revealed by precise high-energy experiments.

Now, in the 21st century, more precise experiments than ever before are occurring, and each anomaly holds the tantalizing possibility of revealing a new fundamental force. Will we ever find a 5th?

Despite all we’ve learned about the nature of the Universe — from a fundamental, elementary level to the largest cosmic scales fathomable — we’re absolutely certain that there are still many great discoveries yet to be made. 

Our current best theories are spectacular: quantum field theories that describe the electromagnetic interaction as well as the strong and weak nuclear forces on one hand, and General Relativity describing the effects of gravity on the other hand. 

Wherever they’ve been challenged, from subatomic up to cosmic scales, they’ve always emerged victorious. And yet, they simply cannot represent all that there is.

There are many puzzles that hint at this. We cannot explain why there’s more matter than antimatter in the Universe with current physics. 

Nor do we understand what dark matter’s nature is, whether dark energy is anything other than a cosmological constant, or precisely how cosmic inflation occurred to set up the conditions for the hot Big Bang. 

And, at a fundamental level, we do not know whether all of the known forces unify under some overarching umbrella in some way.

We have clues that there’s more to the Universe than what we presently know, but is a new fundamental force among them? Believe it or not, we have two completely different approaches to try and uncover the answer to that.  READ MORE...

De all we’ve learned about the nature of the Universe — from a fundamental, elementary level to the largest cosmic scales fathomable — we’re absolutely certain that there are still many great discoveries yet to be made. Our current best theories are spectacular: quantum field theories that describe the electromagnetic interaction as well as the strong and weak nuclear forces on one hand, and General Relativity describing the effects of gravity on the other hand. Wherever they’ve been challenged, from subatomic up to cosmic scales, they’ve always emerged victorious. And yet, they simply cannot represent all that there is.
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There are many puzzles that hint at this. We cannot explain why there’s more matter than antimatter in the Universe with current physics. Nor do we understand what dark matter’s nature is, whether dark energy is anything other than a cosmological constant, or precisely how cosmic inflation occurred to set up the conditions for the hot Big Bang. And, at a fundamental level, we do not know whether all of the known forces unify under some overarching umbrella in some way.

We have clues that there’s more to the Universe than what we presently know, but is a new fundamental force among them? Believe it or not, we have two completely different approaches to try and uncover the answer to that.

Dark Energy

Universe Dark Energy-1 Expanding Universe
This diagram reveals changes in the rate of expansion since the universe's birth 15 billion years ago. The more shallow the curve, the faster the rate of expansion. The curve changes noticeably about 7.5 billion years ago, when objects in the universe began flying apart as a faster rate. Astronomers theorize that the faster expansion rate is due to a mysterious, dark force that is pulling galaxies apart.  Credit: NASA/STSci/Ann Feild






One explanation for dark energy is that it is a property of space. Albert Einstein was the first person to realize that empty space is not nothing. Space has amazing properties, many of which are just beginning to be understood. The first property that Einstein discovered is that it is possible for more space to come into existence. 

Then one version of Einstein's gravity theory, the version that contains a cosmological constant, makes a second prediction: "empty space" can possess its own energy. Because this energy is a property of space itself, it would not be diluted as space expands. As more space comes into existence, more of this energy-of-space would appear. 

As a result, this form of energy would cause the universe to expand faster and faster. Unfortunately, no one understands why the cosmological constant should even be there, much less why it would have exactly the right value to cause the observed acceleration of the universe.


Another explanation for how space acquires energy comes from the quantum theory of matter. In this theory, "empty space" is actually full of temporary ("virtual") particles that continually form and then disappear. 

But when physicists tried to calculate how much energy this would give empty space, the answer came out wrong - wrong by a lot. The number came out 10120 times too big. That's a 1 with 120 zeros after it. It's hard to get an answer that bad. So the mystery continues.

Another explanation for dark energy is that it is a new kind of dynamical energy fluid or field, something that fills all of space but something whose effect on the expansion of the universe is the opposite of that of matter and normal energy. 

Some theorists have named this "quintessence," after the fifth element of the Greek philosophers. But, if quintessence is the answer, we still don't know what it is like, what it interacts with, or why it exists. So the mystery continues.  READ MORE...