The Big Bang, Holograms and Repulsive Gravity
When a load of bricks, dumped on a corner lot, can arrange themselves into a house; when a handful of springs and screws and wheels, emptied on a desk, can gather themselves into a watch, then and not until then will it seem sensible, to some of us at least, to believe that all these thousands or millions of worlds could have been created, balanced and set to revolving in their separate orbits — all without any directing intelligence at all. – Bruce Barton
What is the meaning of life, the universe and everything?
42, of course
Our universe is a magnificent being. It’s such an odd thing yet stunningly so. On one hand there are fiery heavenly bodies twinkling majestically in our night sky while on the other, there are oceans of invisible matter dancing elegantly. The universe is indeed one big machine. Processes occur continuously and everything appears to be in sync. It is true, we are truly made of stardust…we are the remnants of stars gone poof…of stars gone bang…of stars gone dead.
Yet it’s rather scary. We are a mere speck in this entire universe. The humans are generally a proud race…and maybe too proud. We are arrogant little things; some believing that we are the only life out there. I, for one, can’t fathom to begin that out of the billions, gazillions of astronomical objects out there that we are the only ones to be given the grace to form and develop.
Welcome to Part 3 of ‘The Weird and Wacky World of Physics.’ In this thread, I hope to delve into the universe itself and unravel just some of the mysteries it conceals. Once again, if there’s anything you believe is wrong…correct me at anytime…I think this is rather a boring one but I hope you enjoy it nevertheless…
The Inflationary Big Bang Theory
Tune your television to any channel it doesn’t receive and about 1 percent of the dancing static you see is accounted for by this ancient remnant of the Big Bang. The next time you complain that there is nothing on, remember that you can always watch the birth of the universe. – Bill Bryson
It all started with a Big Bang.
13.7 billion years ago, we believe that our own universe was created by this very event. BAM. It just…happened. But what caused this? Why did it bang? What banged? These questions could indeed be the ultimate ones. The B.B is indeed the ‘Holy Grail’ of Physics. It was the beginning of everything as we know it! The origin of space…the origin of time itself. The closer we get to the moment of the Big Bang, the more our equations collapse…..our equations become befuzzling to say the least.
Every Frenchman, fry, fruit…every cat, cart, corn,…every pickle, panda, parakeet…every…well you get the idea. These and all are made up from matter created in the first few seconds of the B.B. It is the defining event of our universe and everything in it. The more we learn about the Big Bang, the deeper the mystery becomes and it once again, brings up more questions such as the multiverse…but how can we focus on that, when unravelling and deciphering one is hard enough itself. All our matter, all of existence itself was compacted into a very small space…a millionth of a billionth of a centimetre across at the dawn of the universe.
Everything, we believe, was at a single point, a single speck. It was unimaginably hot, infinitely small and super dense full of energy. ..and then it expanded…it grew…and it evolved.
Quantum fluctuations created a singularity that was very hot and dense. Our universe at some point, scientists believe, stretched first from this singularity…and as it did this, it cooled.
Photons became quarks…giving rise to the quarks from our current Standard Model:
The quarks became neutrons and protons…which lead to atoms and those clumped together to make stars and galaxies.
It’s thought the universe grew by a factor of at least 10^78 in volume between about 10^-35 and 10^-32 seconds after the Big Bang. Why did this occur? There are some very interesting ideas which I hope to delve into. Inflationary Big Bang. The key is that it stretches space-time. This theory has evolved from the Big Bang and was developed by Alan Guth in 1981. Not at all that long ago. Why do we really like this theory? It provides the solution to two long standing problems with the standard B.B theory; the Horizon problem and the Flatness problem.
While there are many other theories such as God, strings and ‘The Steady State Theory,’ I aim to look at the most prevailing one of our time., a theory that has a slight twist compared to world known BBT. Here’s a very great introduction to summarise the points I hope to glaze over. It describes some of the evidence for the B.B, what actually occurred and the theory itself.
What Caused the Big Bang; Repulsive Gravity and the Inflaton Field?
There is nothing certain in this world. – Benjamin Franklin
It’s one of the biggest questions to confront physics….what caused our universe to magically appear? Changing just one digit or tweaking just one law would mean our universe would be a strange and lethal place. Astronomical phenomena like ours would never exist, rather they would contort in a different environment to produce something much more mind-boggling. In this section, I hope to brush over what may have created our universe.
We all learned at primary school that gravity is an attractive force. It is not only the invisible hand which keeps our feet on the ground but it’s universal, providing us the entertainment of a beautiful dance; keeping the Earth in orbit around the Sun, that star orbiting around the centre of the Milky Way, the Milky orbiting around it’s centre of gravity and so on. Fact is, although gravity is familiar, it’s proved to be the most frustrating for physicists. They just can’t fit it in to their theories (except string theory…that’s why we’re in love with it :lol I mentioned general relativity in my previous thread which is really mostly to do with gravity. It’s not possible to merge quantum theories with general relativity leaving scientists still seeking their GUT. And it’s not just at the small scales gravity screws up. If you look at the grandest cosmic scales…something, again, is just not right with gravity!
The Inflationary Big Bang is an enchanced version of the original. We know that in the first few seconds, there was a rapid increase in space…it indeed did inflate. But what caused this?
It’s often said Einstein blinked…that he went back to his notebooks and tried to rectify his equations of general relativity to make them symbolise that universe that was not only uniform but unchanging. And of course, this was completely sensible at the time. Imagine you were a strong atheist, stubborn that your beliefs are correct. You’re delving into some mathematical equations that leave as a by-product that God exists; of course you don’t believe this can occur and quickly rectify your numbers to get rid of it. That’s what Einstein did, he added what we know to be the ‘cosmological constant.’ It’s one of the “products” that can be seen from G.R ; the amount of energy stitched into the fabric space. Being the curious man he is, he fiddled with it. When entering a positive number for this, Einstein found that the fabric that now contains positive energy would PUSH AWAY from each other, leaving us with…repulsive gravity.
Yes, you read correctly…repulsive gravity. How can that be? Well let’s take a look. Newton and Einstein both spent years trying to reveal the mysteries that gravity concealed and succeeded in many ways. Both developed theories yet there is one massive difference between them. Newton’s theory says that gravity arises solely from object’s mass. Bigger the mass/energy, greater the gravitational pull between 2 objects. However Einstein’s theory takes into account one more thing; the mass AND its pressure. Just like positive pressure leads to an attractive gravitational field, repulsive gravity can be caused by uniform negative pressure.
Uniform negative pressure? If I’m leaving some befuzzling faces, be not confuzzled! While positive pressure pushes outwards, negative pressure pulls inwards. Think of a vaccum cleaner. When you turn it on, an area of negative pressure is formed in the bag of it, which sucks air in as it tries to even out its internal pressure. Along with the air, the vacuum picks up particulate matter, leaving the floors cleaner. Another example can include the inward pull of an elastic band.The inflationary theory suggerstss a kind of repulsive gravity that’s astoundingly short and thunderingly intense. The repulsive gravity is indeed the answer to what caused that large expansion of space in a very short span of time. By answering what caused this inflation, we can also answer a couple of questions e.g. ‘Why does the universe look the same?’ which I’ll talk about further on.
Some genius’ showed that negative pressure emerges naturally from quantum fields. (Physicists don’t make up everything ). Fields are funny little things. You can’t see it’s there but you can see it’s effect. Think of a magnet. If you push 2 poles of 2 different magnets together, it will either push or pull due to it’s magnetic field. Just like flames generate heat, magnets generate a magnetic field. There are a whole variety of other fields such as the electric, strong and weak nuclear, electron, quark and neturino fields. We also believe there is a hypothetical field called the ‘Inflaton Field’ which is carried by inflatons. It’s credited to generate the universe and fuelling its inflation.
Fields carry energy. The larger the value of the field, the larger the energy it has. The field’s value is constant, taking the same value everywhere; therefore the same energy at each and every point even though the field’s value can vary place to place. One amazing guy, named Alan Guth, came up with an amazing insight.
He suggested that just a uniform inflaton field does not only have uniform energy but also uniform negative pressure. This was then developed by a few other guys to come to a refined model; where a burst of inflation can occur and then it being ‘switched off.’ It can all explained by my very poor drawing below (yes as you can see my drawing skills are very poor…thank you Paint for letting me use your understandable tools.)
When you lift an object it is said to have (gravitational) potential energy. The object wants any excuse to relase that energy and if you let go, it will form; converting it’s potential energy to kinetic energy. The energy carried away from a field’s nonzero values are also potentail energy. Below is my friend, Pogston. In the flatter regions, his potential energy doesn’t change very much…but those big slopes you see, if he walks up them…his potential energy would increase sharply. When Pogston rolls down the slope, as shown, inflation releases its potential energy to a lower value. Like so, when the inflation is on the flatter regions it fills space with large potential energy and negative pressure. The energy isn’t lost but it’s converted into a spray of particles; a uniform spread.
But there is a burning question, to me and to many others. The Goldilocks effect. The fine-tuning. Why is inflation, like so many other properties of the Universe ‘just right’ to allow our universe to exist?
The Flatness Problem
Although relativity theory thinks of space-time as being a curved surface, astronomers sometimes describe the universe as ‘flat.’ It’s one where the amount of matter present is just sufficient to halt it’s expansion but it’s insufficient to re-collapse it. This means that parallel light rays remain parallel no matter how far they travel in space, that light’s path across the universe is relatively unaffected, however it can bend itself around a massive body (as seen in general relativity.) To picture it:
The problem arises because we live in a universe that has an observed density parameter that is close to 1. It’s close to the “critical density.”If we go above this critical density, the universe will have enough energy to stop expanding and then contract. If it’s less dense, the gravitational attraction will not be enough to overcome the kinetic energy of the universe expanding. Thing is, the reason we are puzzled is that we’re close to the critical density. After nearly 14 billion years of evolution, it appears not to have shifted much. Surely with the greater mass in our universe (clumping of stars, galaxies), therefore the greater attraction we indeed should have a much higher density.
Seems like a pile of junk, doesn’t it?
Rather, this incredible engineering feat named WMAP (Wilkinson Microwave Anisotropy Probe
Below indicates CMB…a shaper view of the temperature differences. What you can see is that it looks oddly similar to the 1 degree one…hence indicating that our universe is indeed flat! Ground based and balloon-based experiments like MAT/TOCA, Boomerang, Maxima and DASI have shown that the brightest spots are about 1 degree across. Thus showing that the universe is indeed flat…and there’s only a margin of 2% error. Not much hope for those sphere loving kittycats.
The flatness problem is also resolved by the inflationary B.B theory because the act of inflation actually flattens the universe. Picture an uninflated balloon, which can have all kinds of wrinkles. As the balloon expands, though, the surface smoothes out. According to inflation theory, this happens to the fabric of the universe as well. NASA describes how the inflationary theory solves this problem; they described it better than I could:
Imagine living on the surface of a soccer ball (a 2-dimensional world). It might be obvious to you that this surface was curved and that you were living in a closed universe. However, if that ball expanded to the size of the Earth, it would appear flat to you, even though it is still a sphere on larger scales. Now imagine increasing the size of that ball to astronomical scales. To you, it would appear to be flat as far as you could see, even though it might have been very curved to start with. Inflation stretches any initial curvature of the 3-dimensional universe to near flatness.
But the universe presents to us another unusual coincidence.
The Horizon Problem
Imagine we somehow had a spaceship that was millions and billions of light years away from us and came across a habited planet that we’ve had no contact with. The inhabitants spoke the same language and had shops, activities exactly like us. Wouldn’t it be mind-boggling? I mean with no contact, how can they be EXACTLY the same? It’ll bring up a lot of questions and problems. That indeed is just how scientists are feeling. Our universe is the same. This indeed describes the Cosmological Principle, although it applies to large scale distances.
The cosmological principle is usually stated formally as ‘Viewed on a sufficiently large scale, the properties of the Universe are the same for all observers.’ This amounts to the strongly philosophical statement that the part of the Universe which we can see is a fair sample, and that the same physical laws apply throughout. In essence, this in a sense says that the Universe is knowable and is playing fair with scientists.
Our universe appears to be unfathomably uniform. Look across space from one edge of the visible universe to the other, and you’ll see that the microwave background radiation filling the cosmos is at the same temperature everywhere. That may not seem surprising until you consider that the two edges are nearly 28 billion light years apart and our universe is only 14 billion years old. Indeed, this can be termed as the Horizon Problem.
We haven’t and won’t ever contact parts of our universe because light from there has no time to travel to us. Nothing can travel faster than speed of light in a vacuum….no heat, no matter…nothing. That means there will always be some part of the universe untouched by us. In some cases, that’s a good thing. Look what condition we’ve left the Earth in…and the rubbish hauled into space around it. On the other hand…we’ll never know what does indeed occupy those regions.
So…how did 2 completely opposite ends that haven’t been touched turn out to be the same? E.g. the temperature everywhere that we’ve been able to observe is 2.725 K. When you look at 2 different patches of the CMB, their temperatures are the same to within 1 part in 10,000. Nothing can travel faster than the speed of light, so there is no way heat radiation could have travelled between the two horizons to even out the hot and cold spots created in the big bang and leave the thermal equilibrium we see now. According to the inflationary universe model before inflation occurred, the universe was smaller than the horizon distance…so any change was transmitted everywhere.
The Monopole Problem
The lack of symmetry between electric and magnetic fields is one of the oldest puzzles in physics. It’s possible to isolate positive and negative electric carge but not north and south magnetic poles. Paul Dirac first put forward the idea of magnetic monopole in 1931but all the searches so far have appeared to be fruitless.
The magnetic monopole is a HYPOTHETICAL particle that is a magnet with one magnetic pole and therefore will have a charge. These particles are predicted by theories that try to unify all the forces e.g. M theory. Fact is, these are rare so detecting one in a particle accelerator will be a miracle. The Big Bang should have created these. Inflation allows for magnetic monopoles to exist as long as they were produced prior to the period of inflation. During inflation, the density of monopoles drops exponentially, so their abundance drops to undetectable levels.
Here’s a few sites to further read:
Dark Matter May Make Planets Habitable
The Hunt For Dark Matter (Details of Some Experiments)
Second Signal Hints Dark Matter (3th May 2011)
Is the Universe Infinite?
Before the 20th century, people used to believe that our universe had existed forever. Einstein’s G.R predicted the B.B singularity and the Big Crunch’s’. But the question is….does the universe have a beginning or an end? Is our universe closed or open? Again this can be explained apparently by The Flatness Problem.
There is one basic difference between the two is quite simple. Imagine a photon that follows a straight path. In a finite universe it may end up in the same spot as it started out but in an infinite one it will never be able to. In infinite universes, the main difference is the rate of expansion. In an open one…expansion will be forever and constant/accelerated. In the latter, it will be forever but at an asymptotically decelerating rate.
I personally believe that the Big Bang creates a closed universe in an infinite space…if that makes sense? Like bubbles in a never ending space. Here’s a great episode by Cosmic Journeys which brings up a lot of questions. It’s a very informative, and hopefully you’ll enjoy it as much as I did.
The Darkness Is Here…
The universe is made mostly of dark matter and dark energy, and we don’t know what either of them is – Sarah Perlmutter
It is not only disturbing but also embarrassing that we, as scientists, have only seen a minute amount of our universe and most of it we are still unable to decipher its contents. To learn the fact that there is something surrounding us, which we are unaware of is rather scary. Fact is, science can only explain a mere 5% of the universe we abide in…and even that we don’t completely understand! According to modern physics, the empty space that we believe to be “empty” is not. The Red Shift Effect (when a source of light moves away from us, we see an increase in the wavelengths causing a shift to the red end of the spectrum.) has showed us that the universe is EXPANDING! When we found the evidence to that theory, it posed new questions, significantly:
What the hell is causing this?
Let There Be Dark Matter
Take our best understanding of gravity, apply it to the way galaxies spin and you’ll see the problem: the galaxies should be falling apart. Galactic matter orbits around a central point because its mutual gravitational attraction creates centripetal forces. But there is not enough mass in the galaxies to produce the observed spin, spotted this anomaly in the late 1970s. It’s not every day that a woman’s name comes up in this subject but I’m glad it has. Vera Rubin.
Rubin and Ford (an astronomer who developed a spectrometer to measure the red shift) found when making Doppler observations of the orbital speeds of galaxies, something out of the blue. The stars from the centre of the galaxies were moving just as fast as those closer in. Now, I remember learning that as the further the distance away, the smaller the gravitational pull on the object and therefore it would move slower. So this find was completely unexpected. And this just wasn’t in 1 or 2…this was in 60 spiral galaxies, therefore their results were quite accurate! This was the proof to Zwicky’s theory. In 1933, Fritz Zwicky analysed these velocities within the Coma cluster. He found that the galaxies moving within the cluster were moving so fast that if the cluster was only held together by gravity of its visible mass, it would escape. But, there was no indication of it flying apart…and therefore this caused Rubin to understand what she found was actual evidence for Zwicky’s dark matter.
No one knows exactly what dark matter is. Dark matter doesn’t appear to be interacting with EM radiation and therefore as Maxwell’s 4 famous equations describe how moving charges can create electromagnetic radiation (charge produces light), dark matter doesn’t abide. We can’t see it, only detect its gravitational pull on normal matter which it outweighs 5:1. That is 5 times the amount we can see…and I still can’t take in all I’m able to view. To think that there is 5 times the amount is completely stunning! Below is the first images of dark matter being mapped 3D:
Two kinds of hypothetical particles pop out of theories describing the nature of dark matter;WIMPs(Weakly Interacting Massive Particles.) and axions. WIMPs, like the name states, they interact only weakly with normal matter yet they are big and heavy. There indeed has be evidence: COGENT Experiment and the DAMA Experiment. We, however see different results…this may be because of our assumption that WIMPS interact with neutrons and protons in the same way is not true. Small tweaks into theories can indeed correct these and bring everything into line.
380,000 years after the Big Bang, the temperature of the universe dropped below 3000K, allowing atoms to form. This caused a huge amount of energy to be released in the form of light and the expansion of the universe stretched this light to microwave wavelengths. This radiation fills all of space and has proved to be awfully helpful to us.
This Cosmic Background Radiation (CMB) tells us how matter was distributed throughout space in the youthful stages of the universe due to the variations of hot and cold patches. Dark matter began clumping together due to gravity earlier than matter did and therefore it can be seen in some of these patches; at an angle of 0.25 degrees in the sky. CMB also allows us to determine how much dark matter must be present. What’s remarkable is that for every gram that we can see in the universe, there has to be 5 grams of those what we can’t see. Moreover, this doesn’t include dark energy.
Every now and again cosmologists decide that the universe needs redecorating. Sometimes they declutter, as when Copernicus and Kepler shuffled the sun and the Earth to get rid of all those epicycles and make the planets move in straightforward orbits. Sometimes they embellish, as when Einstein decided that there’s more to space than good old-fashioned nothingness, and introduced the concept of a deformable space-time – Stuart Clark
Not only did the CMB indicate dark matter but also dark energy (and BOOMERANG was part of finding it). It’s left a shadow, an imprint onto microwaves and changes the temperature of the CMB due to effects on gravity on the energy of photons. In 1998, astronomers discovered that the universe is expanding at ever faster speeds. It’s an effect still searching for a cause – until then, everyone thought the universe’s expansion was slowing down after the big bang. One suggestion is that some property of empty space is responsible – cosmologists call it dark energy. When we talk about dark matter, we are in danger of imagining it to be like ordinary matter. In fact, dark matter’s invisibility tells us that is has another remarkable attribute. It is not made up of charged particles unlike normal matter.
It is one of the biggest conundrums in science. Dark energy, where gravity is repulsive rather than attractive and we can bring back Einstein’s cosmological constant. Theoretical physicists are having trouble to fit it into their existing theories. How space and time looks depends on dark energy; it’s so pivotal. Below are 4 ways we could expand the universe:
When physicists don’t understand something, they invent a new field to explain it. That trait seems to have also affected astronomers. In the case of the dark energy mystery, the result is a quantum field called quintessence. It’s said to saturate the universe but one of the key differences between this and the cosmological constant is that it depends on time and the place. There are loads of different versions. One version, called phantom energy, builds with time…causing expansion to go faster and faster until the eventually the universe rips to pieces. But there are many problems, one being the fact that no quintessence force has shown itself and no particles appear as fluctuations of the field (no gauge boson.)
Another way we could try to combine dark energy is by modifying an old force; gravity. One such example is by a guy called Gia Dvali. He has developed a modified theory of gravity in which space-time is not as formless as we believe. In his theory, he suggests that it has a limiting underlying shape that makes it look like as if energy is warping it. Of course, this warping actually occurs due to gravitons (the gauge bosons, “force carriers”) which are hypothetical. This modification would also explain the acceleration of the universe’s expansion.
Lastly, I want to mention one so ingrained into cosmology that scientists have forgotten it’s there. The Cosmologic Principle….that the universe has no preferred places or directions. But that is just an assumption introduced by Friedman in the 1920s…yet it might be time to ditch it. If the universe is no longer the same everywhere, effects of general relativity that are negligible in a uniform cosmos would probably become much more important. Physicists for decades are trying to meld together general relativity with quantum mechanics…and if we can, we’re on our way to the GUT.
The Holographic Principle
I’d like to bring a very slight touch of this principle into this thread for it appears to have made quite an impact onto the physics society.
The holographic principle is a mathematical principle that the total information contained in a volume of space corresponds to an equal amount of information contained on the boundary of that space. This dependence of information on surface area, rather than volume, is one of the key principles of black hole thermodynamics.
The universe can be thought of as an information processer. It produces information, dependent on how things are now. Everything seems to emerge from information…arising from this fundamental ingredient and evolving to the fundamental rules of physics. Information is vital to everything we do and it seems that the concept of it will be dominating our race for the next few decades, if not centuries. Below is a video which will literally tell you all you need to know about it. It’s better than anything I can write!
The main basis of this principle is that all information contained in some region of space can be represented as a ‘hologram’ – a theory which `lives’ on the boundary of that region. For example, let’s imagine the region of space is a room. The H.P means that all the information that the assets that all of the physics which takes place in the room can be represented by a theory which is defined on the walls of the room. Now applying this to an astronomical object:
For a black hole, the principle states that all the information that will ever fall into it, is contained in surface fluctuations of the event horizon. However, Hawking showed that black holes are in fact not ‘black’ but emit radiation; causing them to evaporate and eventually disappear. When it has gone, all the information about the star that collapsed to form it has been destroyed. If any of you took Physics to GCSE standard, you’d learn the ‘Conservation of Energy Principle’: Energy cannot be created or destroyed.The Holographic Principle helps to resolve the black hole information paradox within string theory.
And this is just not a random theory that people are working on. There’s a lot of evidence coming in. In the corner of a field stands an assortment of boxy temporary buildings covered with corrugated iron. Underneath the metal sheets, however lies something much more interesting….a detector that stretches for 600 metres. This German set-up has been looking for gravitational waves; ripples in space-time thrown by dense objects e.g. neutron stars, black holes. The GEO600 detector hasn’t detected any of these waves so far but has made another discovery; ‘noise’ that is plaguing their detector. According to some physics, GEO600 has stumbled upon the fundamental limit of space-time…quantum convulsions; where space-time stops acting smooth and crumbles into ‘grains’ like zooming in to an image to see the dots. There is no actual evidence that this noise can somehow prove the holographic principle yet modifications are now occurring to further finetune the detector, make it more sensitive.
The concept of holography has lured philosophers of science for decades, and is becoming more and more popular lately. This paper claims that the fuzziness in quantum mechanics, in statistical physics and thermodynamics is due to the fact that we do not see the real image of the object, but a holographic projection of it. They found that the projection of a point particle is a de Broglie-type wave. This indicates that holography could be the origin of the wave nature of a particle. Furthermore, they have also noticed that one cannot stabilize the noise in terms of the integration grid-points of the hologram; it means that one needs to give the grid-points a physical significance. They further claim that the space is quantized, which supports the basic assumption of quantum gravity.
Remember my friends, that we are indeed a small speck of dust in this entire universe…forget about these meaningless things like war and hatred…and truly embrace what we have. Because I tell you what, we all should be honoured we can experience such beauty like this and rather than destroy it, sustain it.