If you were in a Virgo Cluster galaxy today, and you had a telescope powerful enough to study Earth, you would be able to see the prehistoric reptiles.
Why isn’t the night sky uniformly at least as bright as the surface of the Sun? If the Universe has infinitely many stars, then presumably it should be. After all, if you move the Sun twice as far away from us, we will intercept one quarter as many photons, but the Sun’s angular area against the sky background will also have now dropped to a quarter of what it was. So its areal intensity remains constant. With infinitely many stars, every element of the sky background should have a star, and the entire heavens should be at least as bright as an average star like the Sun.
(We say “at least as bright” because the stars of such a bright universe would begin to absorb heat from their neighbours, and precisely what happens when a star is heated is a technical matter for thermodynamic and nuclear theories. We don’t expect such stars to cool down, but neither do we expect them to heat up indefinitely. Olbers’ Paradox originated before physicists had developed the nuclear theory of how stars shine; thus, it was never concerned with how old the stars might be, and how the details of their energy transactions might affect their brightness.)
The fact that the night sky is not as bright as the Sun is called Olbers’ paradox. It can be traced as far back as Kepler in 1610, and was rediscussed by Halley and Cheseaux in the eighteen century; but it was not popularized as a paradox until Olbers took up the issue in the nineteenth century.
There are many possible explanations which have been considered. Here are a few:
There’s too much dust to see the distant stars.
The Universe has only a finite number of stars.
The distribution of stars is not uniform. So, for example, there could be an infinity of stars,
but they hide behind one another so that only a finite angular area is subtended by them.
The Universe is expanding, so distant stars are red-shifted into obscurity.
The Universe is young. Distant light hasn’t even reached us yet.
If the universe were infinite and filled with stars in a uniform distribution, then every line of sight would terminate on the surface of a star and should be bright. To be sure, those further away would be fainter, but there would be more of them. Careful analysis suggests that the sky should be as bright as the surface of an average star.
Noting that the night sky is obviously not that bright, there are two lines of explanation. First, the universe appears to be of finite age and that light from stars at an infinite distance would not have reached us in the age of the universe. Second, we observe that the universe is expanding and that stars further away from us are receding at a faster rate. The result of this expansion is that the light from more distant stars is Doppler shifted more toward the red and beyond a certain distance would not contribute significantly in the visible region of the electromagnetic spectrum.
Aliens may be ‘staring us in the face’ according to Lord Martin Rees, the president of the Royal Society Lord Martin Rees, president of the Royal Society and astronomer to the Queen, said the existence of extra terrestrial life may be beyond human understanding.He made the remarks shortly after hosting the national science academy’s first conference on the possibility of alien life.They could be staring us in the face and we just don’t recognise them. The problem is that we’re looking for something very much like us, assuming that they at least have something like the same mathematics and technology,” he said.“I suspect there could be life and intelligence out there in forms we can’t conceive. Just as a chimpanzee can’t understand quantum theory, it could be there as aspects of reality that are beyond the capacity of our brains.”
An object you can see in front of you may exist simultaneously in a parallel universe.
“When you observe something in one state, one theory is it split the universe into two parts,” Cleland told FoxNews.com, trying to explain how there can be multiple universes and we can see only one of them.
The multi-verse theory says the entire universe “freezes” during observation, and we see only one reality. You see a soccer ball flying through the air, but maybe in a second universe the ball has dropped already. Or you were looking the other way. Or they don’t even play soccer over there.
Carroll suggests that we don’t exactly feel time — we perceive its passing. For example, time moves fast on a rollercoaster and very slowly during a dull college lecture. It races when you’re late for work . . . but the last few minutes before quitting time seem like hours.
“Time seems to be a one-way street that runs from the past to the present,” says Fred Alan Wolf, a.k.a. Dr. Quantum, a physicist and author. “But take into consideration theories that look at the level of quantum fields … particles that travel both forward and backward in time. If we leave out the forward-and-backwards-in-time part, we miss out on some of the physics.”
Wolf says that time — at least in quantum mechanics — doesn’t move straight like an arrow. It zig-zags, and he thinks it may be possible to build a machine that lets you bend time.
Cleland has proved that quantum mechanics scale to slightly larger sizes. The next challenge is to learn how to control quantum mechanics and use it for even larger objects. Do so — and we might be able to warp to parallel universes just by manipulating a few electrons.
“Our concepts of cause and effect will fly out the window,” says Ben Bova, the science fiction author. “People will — for various reasons — try to fix the past or escape into the future. But we may never notice these effects, if the universe actually diverges. Maybe somebody already has invented a time machine and our history is being constantly altered, but we don’t notice the kinks in our path through time.”
It’s raining planets. Members of the science team for NASA’s Kepler telescope have just announced the tentative discovery of more than 1,200 worlds orbiting distant stars. Of these, approximately four dozen are candidates for being Earth’s doppelgangers — planets that could be layered by a liquid ocean and a thick atmosphere. Worlds that might conceivably host life.
Within a thousand light-years of Earth there are at least 30,000 of these habitable worlds.
Well, perhaps they’re only habitable, and not inhabited.
After a journey that had lasted eight months, and covered 352 million miles of space, Curiosity performed a series of aerial acrobatics before landing safely near the equator.
Jubilant scientists hugged, wept and distributed Mars chocolate bars to each other as one of them announced: “Touchdown confirmed. We are wheels down on Mars. Oh, my God.”
Minutes later Curiosity sent back pictures showing one of it wheels, and its own shadow on the Martian surface.
Curiosity is Nasa’s seventh landing on Earth’s neighbour but the most ambitious and expensive.
Adam Seltzner, leader of Curiosity’s descent and landing team, had previously admited to being “rationally confident but emotionally terrified.”
Curiosity will search for evidence that Mars may once have held the necessary building blocks for microbial life to evolve.
It has an array of sophisticated chemistry and geology gadgets for analysing soil and rocks.
It also has cameras and a robotic arm with a power drill, and a magnifying imager that can reveal details smaller than the width of a human hair. Samples will be analysed using a state-of-the-art onboard laboratory.
Curiosity will face several weeks of health checkups before taking its first short drive on the Martian surface.
Curiosity will look there for basic ingredients essential for life, including carbon, nitrogen, phosphorous, sulphur and oxygen.
Pluto has been voted off the island.Pluto will now be dubbed a dwarf planet. But it’s no longer part of an exclusive club, since there are more than 40 of these dwarfs, including the large asteroid Ceres and 2003 UB313, nicknamed Xena—a distant object slightly larger than Pluto. “We know of 44” dwarf planets so far. “We will find hundreds. It’s a very huge category.”
What Is a Planet Today?
According to the new definition, a full-fledged planet is an object that orbits the sun and is large enough to have become round due to the force of its own gravity. In addition, a planet has to dominate the neighborhood around its orbit. Pluto has been demoted because it does not dominate its neighborhood. In addition, bodies that dominate their neighborhoods, “sweep up” asteroids, comets, and other debris, clearing a path along their orbits. By contrast, Pluto’s orbit is somewhat untidy.
A planet (from Ancient Greek αστήρ πλανήτης (astēr planētēs), meaning “wandering star”) is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals. Planetesimals are solid objects thought to exist in protoplanetary disks and in debris disks. The word planetesimal comes from the mathematical concept infinitesimal and literally means an ultimately small fraction of a planet.While the name is always applied to small bodies during the process of planet formation, some scientists also use the term planetesimal as a general term to refer to many small Solar System bodies – such as asteroids and comets – which are left over from the formation process. There are eight planets and five recognized dwarf planets in the Solar System. In increasing distance from the Sun, the planets are:
Mercury – Venus – Earth – Mars – Jupiter – Saturn – Uranus – Neptune
If we believe space and time are infinite, by law of probability we can say that there is an infinite amount of other worlds undergoing the exact same path as us in the exact same way. In other words, there is a person in another world exactly like me, doing and thinking the exact same thing i’m doing right now. So if I believe in paralell universes, my infinite exact counterparts do too. And if I say “hello inifinite counterparts of me” then all the counterparts are saying hi too. So i just said hi to an infinite number of my counterparts and an infite amount said hi too at the same time. 😉
Parallel universes can happen because the theory allows for an infinite universe, but there’s only a finite way that stuff can be organized, so sooner or later our universe is bound to repeat.
There are only so many ways matter can arrange itself within that infinite universe. Eventually, matter has to repeat itself and arrange itself in similar ways. So if the universe is infinitely large, it is also home to infinite parallel universes.
Does that sound confusing? Try this:
Think of the universe like a deck of cards.
“Now, if you shuffle that deck, there’s just so many orderings that can happen,” Greene says. “If you shuffle that deck enough times, the orders will have to repeat. Similarly, with an infinite universe and only a finite number of complexions of matter, the way in which matter arranges itself has to repeat.”
Greene thinks the key to understanding these multiverses comes from string theory, the area of physics he has studied for the past 25 years.
In a nutshell, string theory attempts to reconcile a mathematical conflict between two already accepted ideas in physics: quantum mechanics and the theory of relativity.
“Einstein’s theory of relativity does a fantastic job for explaining big things,” Greene says. “Quantum mechanics is fantastic for the other end of the spectrum — for small things. The big problem is that each theory is great for each realm, but when they confront each other, they are ferocious antagonists, and the mathematics falls apart.”
String theory smooths out the mathematical inconsistencies that currently exist between quantum mechanics and the theory of relativity.
If, when I was growing up, my room had been adorned with only a single mirror, my childhood daydreams might have been very different. But it had two. And each morning when I opened the closet to get my clothes, the one built into its door aligned with the one on the wall, creating a seemingly endless series of reflections of anything situated between them. It was mesmerizing. I delighted in seeing image after image populating the parallel glass planes, extending back as far as the eye could discern. All the reflections seemed to move in unison — but that, I knew, was a mere limitation of human perception. To be sure, reflected images don’t have minds of their own. But these youthful flights of fancy, with their imagined parallel realities, resonate with an increasingly prominent theme in modern science — the possibility of worlds lying beyond the one we know.
“An infinite number of appearances with a finite number of outfits ensures infinite repetition.”
Infinite variations of ourselves, our lives and our solar system are within the theorist’s realm of possibility.
Lots of recent research in physics has made the canvas of reality look much wider than we ever imagined. Our most refined cosmological theories indicate, for instance, that the big bang, which created our own universe, may not have been a unique event. There may have been (and may still be) various big bangs at far-flung locations, each one creating its own universe. Our “everything” may be just one enormous expanding bubble in a gigantic cosmic bubble bath of universes.
“There are many perfect copies of you out there in the cosmos, feeling exactly the same way. And there’s no way to say which is really you.”
Imagine that I line up all your duplicates and ask: “Which of you is the David Gelernter?” All of them would raise their hands, and none of them is being deceptive. Each of these beings really thinks that he is you. And each is fully justified in saying so. Each has had all of your experiences, and each has all your memories. My point is that none of the clones is any more justified than any other in having this thought. There is no “real” you that is somehow distinguished from the others. It depends on whether you’re looking from within a mind or from outside.
,,The most incomprehensible thing about the universe is that it’s comprehensible.,, (Einstein)
,,Your reality is the sole reality. You are alone. Your consciousness is all there is.,,
The idea of parallel universes basically says that space is so big that the rules of probability imply that surely, somewhere else out there, are other planets exactly like Earth. In fact, an infinite universe would have infinitely many planets, and on some of them, the events that play out would be virtually identical to those on our own Earth.
We don’t see these other universes because our cosmic vision is limited by the speed of light — the ultimate speed limit.
Any universe that physicists can get to work out on paper would exist, based on the mathematical democracy principle: Any universe that is mathematically possible has equal possibility of actually existing.