In their article, the scientists propose a new model with dark energy and our universe riding on an expanding bubble in an extra dimension. So, one idea for the dark energy is that it is a modern version of the cosmological constant. Because string theory has made so few specific predictions, it’s hard to disprove it, but the theory has fallen short of some of the hype about how it will be a fundamental theory to explain all the physics in our universe, a “theory of everything”. This drastic shift in theory emerged as a result of the realization that space possesses its own energy, dark energy, whose repulsive force is responsible for the increasing rate of expansion that has been observed through two key techniques.
Scientists have proposed all kinds of theories to explain dark matter and dark energy, and “a lot of alternate theories to general relativity start with adding an extra dimension”, said graduate student Maya Fishbach, a coauthor on the paper. Thus, to discover the right quantum theory of gravity and cosmology we must find a new way to formulate quantum theory, as well as the notions of time and change, to apply to a system with no fixed background, which contains all its possible observers. The universe has been expanding since the time of the Big Bang, about 14 billion years ago. This is in contrast to the traditional static vacuum energy or cosmological constant. What about dark energy, vacuum energy, or a cosmological constant?
Einstein’s theory of general relativity explains the solar system very well, but as scientists learned more about the universe beyond, big holes in our understanding began to emerge.
It’s the gravity that shapes the large scale structure of the universe, even though it is the weakest of four categories of forces.
That lifetime is at least 450 million years, the scientists found. In fact, researchers are currently rejoicing at the prospects of exploring life on Earth. Two, that on a large scale, the distribution of matter is about the same everywhere. What’s new, is evidence that the expansion of the universe has actually been speeding up, and that the more recent history of cosmic expansion shows galaxies zooming away from each other faster than the galaxies were receding from one another in the distant past. So dark energy could not be seen until we could measure things very, very far away. In all fairness, 70 % of the Universe’s energy density is dark energy. The accelerated expansion of our Universe was one of the biggest surprise discoveries of all-time, and something that still lacks a good physical explanation.
According to the Cosmic Microwave Background, the rate that the Universe is expanding today ( the Hubble rate of expansion ) is 67±1 km s Mpc, while according to the other ( distance ladder ) method, that rate is 74±2 km s Mpc. After the discovery of the expanding Universe, scientists considered that there was a great cosmic race from the moment of the Big Bang.
Of course, no other theory anticipated an accelerating expansion of the universe either. In fact, the data show that the strength of repulsion can not have changed by more than about 20 % over the past eight billion years, when the universe was just half of its current size.
Because of supersymmetry, string theory requires a large number of particles beyond what scientists have ever observed. Instead of narrowing in on a single vacuum ( solution ) that could be used to explain the universe, it began to look like there were an absurdly large number of vacua. One problem with this is that instead of the 18 fundamental particles in the Standard Model, supersymmetry requires at least 36 fundamental particles ( which means that nature allows 18 particles that scientists have never seen! ). But dark energy has been on their minds only since 1998, when two independent studies of type 1a supernovae revealed the bright, exploding stars to be fainter than expected, hinting that the expansion of the universe is speeding up.
Scientists previously thought that, under Einstein’s Theory of General Relativity, the expansion of the universe would slow as time went on due to the pull of gravity. Before that, gravity had been the dominant force in the universe, but then something else took over, relentlessly pushing parts of the cosmos away from one another. Dark matter is an invisible, mysterious substance that makes up about 27 percent of all matter and energy in the universe. In order for the effect of density differences to be important enough to notice, they would need to be very pronounced on large scales of tens to hundreds of millions of light years. But until this has been determined, they argues that astronomers can not say for sure that the accelerating expansion is due to dark energy. It turns out that the kind of matter that makes up the stars we see with our telescopes, and that we are made of, only amounts to a small fraction, about 5 %, of the mass and energy in the universe.
The technique takes advantage of the observation that the outer reaches of galaxy clusters, the largest structures in the universe held together by gravity, show similarity in their X-ray emission profiles and sizes. Some of the Universe’s most important secrets are hidden in the shape of a beautiful undulating curve: the power spectrum of the cosmic microwave spectrum. Knowing the facts and the theories are good enough for some of us, probably a minority. This surprising and beautiful idea has been confirmed by many precision experiments.
Two of these are dark matter, one of the basic ingredients of the universe; and dark energy, the mysterious force that’s making the universe expand faster over time. When you do this, you realize that the universe had to be much smaller than it is now. Studies of the waves generated during earthquakes continue to provide evidence of the amazing design of Earth’s interior. The Planck mission has made the most precise map ever of the oldest light from our universe, the cosmic microwave background, harking back to less than 400,000 years after the big bang. Even on a diet, a black hole produces lots of X-rays. The modern idea is that empty space is not completely without properties.
A breakthrough in the study of ghostly particles called high-energy neutrinos that traverse space, zipping unimpeded through people, planets and whole galaxies, is giving scientists an audacious new way to expand our understanding of the cosmos. Important, because the physical world – as we know it – is made of those 2 fields: electrical & magnetic fields of Energy. Dark matter makes up 85 % of the Universe and is responsible for its underlying structure.