What is the Shape of the Universe?

When you stare up at the stars from an empty field, or from the top of a mountain, well away from the light pollution of cities and roads, it is truly a marvelous sight. The stars seem to form a heavenly dome above your head, twinkling down at you from the massive, endless expanse of space.

In our explorations of outer space, we have made some amazing discoveries – black holes, dark matter, galaxies containing hundreds of billions of stars, and spectacular nebulae. We can place all of these celestial objects in a relative “map” in relation to our planet, but try thinking outside the box a bit….

Think beyond our planet, solar system, galaxy, and even the universe. Imagine stepping outside of the universe and peering down like some sort of extra-universal super-being. The million-dollar question, of course, is….what would you see? What is the shape of the universe?

Mind-Boggling and Fascinating

It can be difficult for human beings to conceive the vastness of space. At a certain point, the massive distance and scope of the term “infinite” become too great; a relative perspective becomes almost impossible. Furthermore, that confusion happens when we are still discussing things within our universe, let alone when considering the idea of stepping outside of it! Fortunately, there are a number of scientists who enjoy stretching their brains to those incredible proportions, and while we don’t have a definite answer to this head-scratching question, we do have a few possible answers…

Einstein… As Always

Whenever theories or debates about space arise, it seems like Albert Einstein’s name inevitably pops up, and this particular question is no different. To understand the shape of the universe, we need to dip our toes into Einstein’s theory of general relativity. If you think you already understand it well enough, this is what that German genius has to say…

In extremely simple terms, Einstein posited that space, time, mass, and energy were inextricably linked. He argued that gravity can bend light, affect time, and even determine the shape of space itself. Gravity is generated by objects with mass, so the next logical step in that argument is that mass can change the curve of space.

Since the universe, as we know it, is filled with celestial objects and bodies that possess mass, space also has a density (the amount of mass spread over the amount of volume). The important factor here is “critical density”, which is the point where the universe is said to be “balanced”. This critical point is calculated based on the expansion rate of the universe.

Now, when the Big Bang occurred, and for the approximately 14 billion years since then, the universe has been expanding rapidly (some even say it’s speeding up!). Scientists have observed that everything in space appears to be flying away from everything else (on a grand scale). The great question of our modern astronomical age is whether that expansion is going to continue, stop, or reverse.

Credits:Designua/Shutterstock

That is precisely where this discussion of the universe’s shape gets interesting.

Our Three Possible Universes

So, now we know that we have a “critical density” of the universe, but what about the actual density (calculated based on mass and volume)? Well, since we can only observe roughly 14 billion light years in any direction from an observable point, scientists have a rather good idea of the “observable universe”, but that means we only know the volume and the estimated mass of the observable universe. Hence, the uncertainty, and the three following possibilities…

Option 1: Actual Density Greater than Critical Density – In this scenario, the shape of the universe is a perfect sphere. Essentially, the universe contains enough mass to eventually stop the expansion, which has been moving outwards from the point of the Big Bang. This version is called a “closed universe”, with no beginning or end (a sphere). Eventually, the expansion will reverse, and we will experience the opposite of the Big Bang, with the entire universe compressing in on itself. This uncomfortable fate is popularly called “The Big Crunch”.

Option 2: Actual Density Less than Critical Density – In this scenario, the shape of the universe is the same as a saddle, or a hyperbolic form (in geometric terms). Here, the universe doesn’t have enough mass to stop the expansion, and it will continue expanding outwards forever. This version is called an “open universe”.

Option 3: Actual Density Equals Critical Density – In this scenario, the shape of the universe is completely flat and infinite. While this seems like the least likely (that the two densities are just perfectly balanced), this is actually the most popularly assumed theory in scientific circles. The expansion will slow down gradually, perhaps over tens or hundreds of billions of years, until a stasis point is achieved, but there will be no great contraction or “Crunch”.

Shape of Universe where Ω is the density parameter (Credits:NASA/Wikipedia)

What Does This Mean for Us?

While it’s a lot of fun to think of our role in the grand cosmic displays above our heads, the truth is, the shape of the universe and the various density measurements discussed above will never affect our lives. Again, it is difficult to comprehend the scale of light years and the universe, and it is almost impossible to conceive billions of years. Whether we end up stretched out into an icy, infinite, frozen universe, or crunched back down into a singularity, we certainly won’t be around to see it. We can guess at the answers, but we are still limited by the observable universe and mystified by the hundreds of other unexplained phenomena and anomalies of the cosmos.

However, if we could step outside of the universe and look down at its shape (whatever it happens to be), it would certainly be a glorious sight!

How Can We Create Artificial Gravity?

Gravity is one of the fundamental forces of the universe. It defines the world as we know it by binding the cosmos together. Without gravity, everything would constantly move away from everything else. It’s such a basic building block of physics that we often take it for granted. It’s frightening to think about what would happen if someone just simply turned Earth’s metaphorical gravity switch off. We would be flung off the surface of the earth into space due to inertia of the Earth’s rotational motion. If we turned the Sun’s gravity off, there would be nothing holding the solar system together. We’d witness chaos on an incredible scale with planets colliding into each other and meteors raining down on us like a storm of destruction.

However, as essential as gravity is, there are some scenarios in which some degree of control over it would be tremendously useful. Imagine flying without airplanes or transporting heavy objects with almost no effort. Astronauts currently experience many physiological changes during weightless space travel, and most of these changes affect them negatively. They suffer from muscular dystrophy, bone mass loss, disorientation and other zero-g effects. Therefore, interstellar travel would be much easier if gravity could be synthesized artificially. What goes up must come down, right? Is that a fact? The bigger you are, the harder you fall? Truth or fiction? 

Now, let’s see how close we are to actually harnessing the force of gravity.

Defining Gravity

Gravity is the force of attraction that two objects exert on each other. The magnitude of this force increases as the bodies become more massive, and decreases if the bodies move further away from each other. Also, gravitational force always acts in a direction that tries to bring the two objects closer together. Ultimately, gravity is a force that can only bring two objects together, not drive them apart. It doesn’t require the two objects to be in actual contact and is always active (varied in magnitude) for each and every pair of objects in the universe without exception.

How to simulate gravity?

Rotation: Travel in a rotating Spaceship

Gravity, by definition, is a force of attraction, but there are other ways in which two bodies move towards each other. One of these ways could be using a rotating spacecraft, which would induce conditions that are normally observed in a centrifuge.

The rotation would drive any object inside the spacecraft towards the base and away from the center of rotation. The resistive force from the base of the hull would act like the normal force exerted on us by the Earth’s surface while standing. The centrifugal force pushing us towards the base of the hull would act like the gravitational force that the Earth exerts on us.

However, there is one caveat. In this system, the artificial levels vary greatly based on the distance from the center of rotation. Hence, the artificial gravity experienced at the head would be greater than that at the legs. This could make movement and changing body position awkward. However, this effect could be reduced if the radius of the ship was kept much larger than the height of an average person.

Linear Acceleration: Travel in a Space Roller Coaster

An increase in speed, i.e. acceleration, is brought about due to gravity. This is the main reason why, when we free fall, our speed increases. This acceleration can be simulated in the form of an accelerating spacecraft. A spacecraft under constant acceleration in a straight line would give the appearance of gravitational pull in the opposite direction. This would cause the object being accelerated to experience a force pulling it backwards. If you’re wondering how comfortable it would be in a constant state of acceleration, don’t worry, because that’s what you experience all the time due the Earth’s gravitational pull, roller coasters and sports cars. Also, the body won’t know that it’s moving if there is no acceleration. Think about it… the Earth rotates at about 1700 kilometers per hour at the Equator, but we don’t feel it because this speed is constant and there is no acceleration.

Linear acceleration in space travel would require huge amounts of rocket fuel, whereas the rotation strategy doesn’t need any continuous application of force. Nevertheless, constant linear acceleration is desirable, since in addition to providing artificial gravity, it could theoretically provide relatively short flight times around the solar system.

Magnetism:

There is a method by which the effects of gravity can be created using dia-magnetism, but it requires extremely powerful magnetic fields. With such strong magnetic fields, it is doubtful that it will ever be safe for use by humans. Experimentally, frogs and even rats have been levitated against the Earth’s gravity, but that is a very small scale. The machines using dia-magnetism to simulate gravity can be used to induce low gravity conditions safely, and the strength is similar to what one might experience in lunar or Martian gravity.

Live frog levitating inside a magnetic field

Para-gravity:

Artificially simulated gravity in a spacecraft that is neither rotating nor accelerating, also known as ‘para-gravity’, has been hypothesized, but there is no confirmed technique, at present, that can simulate gravity other than mechanical or magnetic acceleration. However, Murphy from Interstellar figured it out, so how hard could it be?

Other than the above-mentioned methods, there are simpler methods to negate the effects of gravity and obtain near zero-g conditions. Those huge human centrifuges with a long rotating arm that we see in cartoons and movies are actually very useful in preparing astronauts for high-g conditions during launches.

Neutral buoyancy is another technique in which people are trained to tackle low-g by performing simple tasks in the simulated environment of a swimming pool.

Neutral Buoyancy is not weightlessness, since we can still sense the direction of gravity underwater, but this comes very close to approximating spaceflight conditions.

 That's What artificial gravity Is

10 Things About the Solar System Your Teachers Never Told You

Any science classroom would seem incomplete without a picture of the solar system. The Sun is always in the center, along with eight planets (nine, if you, like me, love Pluto a bit too much) orbiting around it, followed by the Kuiper belt, all of which is contained within the enigmatic Oort Cloud. We can see their opulence, and wonder at the magnificence of the Great Beyond – the vast blackness of deep space.

The only thing is… all of these pictures are wrong. Sorry to disappoint you or shatter those childhood dreams.

 I’m not claiming that the positions of the planets are wrong, or that the asteroid belt is some conspiracy propagated by the Illuminati. The content of these classroom diagrams isn’t up for debate, but what is problematic is the fact that they ignore the most important feature of the Solar System – all the space inside of it. Confused? Let’s take a trip through the Solar System and try to understand just how vast it truly is.

1. Let’s start with the inner planets first. They happen to be very close to the Sun, so there’s nothing extraordinarily dramatic about the distances between them. What is dramatic though, is their minuscule sizes. If the Sun’s diameter was reduced in scale to 30 cm (the average length of a ruler), Mercury would be 1 mm wide, Venus would be 2.6 mm, Earth would be 2.7 mm wide, and Mars would only be 1.4 mm wide. The inner planets are basically the size of a period in comparison to an A4 notebook paper Sun!
   
2. The journey from Mars to Jupiter is 3 times as long as the journey from the Sun to Mars. Sure, it has the asteroid belt in between, but that isn’t as packed with asteroids as you may think. As a matter of fact, if you clumped all the asteroids together, they would only constitute about 4% of the Moon’s mass. In other words, don’t worry about your favorite sci-fi spacecraft getting smashed to bits by asteroids – there’s plenty of empty space around them!
   

   Science Fiction Lies
   
   
3. Jupiter happens to be significantly larger than all the inner planets, but the Sun is still about 10 times larger than Jupiter – the 5th planet from the Sun.
   

   Credit: Tristan3D
   
   
4. The next big and beautiful planet on our journey is Saturn! This is another gas giant, much like Jupiter, and is approximately 12 times smaller than the Sun. As we go further away from Saturn, there is hardly anything out there that grabs our attention. You see, humans aren’t evolved to understand the scale of emptiness that defines the majority of the universe, and our solar system. If we see a point, we immediately search for another, because everything in between is inconsequential to us. However, the universe in which we live wasn’t created to accommodate our narrow mindsets.
   

   Neil Degrasse Tyson. PREACH.
   
   
5. Finally, we reach Uranus, but if you think we’re nearing the end of our journey, think again. Uranus is actually somewhere around the midpointbetween the Sun and Pluto.
6. Neptune is far away. I mean really, really far away. The distance from Jupiter to Neptune is 5 times longer than the distance from Earth to Jupiter. At this point, you’re probably realizing that the universe is made up almost entirely of Nothing. Technically, it’s 99.999999999999999999958% nothing but Nothing.
7. At long last, we reach Pluto. Perhaps you can see why some people no longer consider it a planet anymore. To be fair, it is really remote – 40 timesfarther away from Earth than the Earth is from the Sun. If Jupiter was as large as the period ending this statement, Pluto would still be 10 meters away! Not only that, but Pluto is also tiny – less than half the size of Mercury, to be precise.
8. That’s a pretty exhausting trip, don’t you think? If a map of the Solar System was created to scale, with the Moon being the size of a single pixel, 1,256 computer screens held side-by-side would be required to encompass the entire length, from the Sun to Pluto. If printed, this map would be 145 meters long (475 ft), which is about the size of 1.5 football fields.
   

   Mind. Blown.
   
   
9. Wait! You may not believe this, but we’re not quite done yet! We still have the Kuiper belt to navigate, and we still have to reach the Oort cloud. Surely it can’t be that far out, right?
   The fastest spacecraft ever made is New Horizons, which just recently sent back amazing high-definition images of Pluto. At a speed of 58,536 km/hr (36,372 miles/hr), it took New Horizons 9 years and 9 months to reach Pluto.
   If we continued traveling at the same speed beyond Pluto, we would reach the Oort cloud  – and I am so sorry to say this- in 10,000 years.
   
10. Yup. The Oort Cloud is REALLY far away. The distance from the Sun to Pluto is just 1/50,000th of the way out of the Solar System. With almost nothing out there but random icy rocks like Pluto, as well as potential comets, traveling beyond Pluto is ‘uneventful’ to say the least.
    

How Does A Touch Screen Works

Smartphones have become an integral part of modern life. With their reserves of information and apps to do anything you desire, they have become our beloved personal assistants. Initially, smartphones started out as humble mobile phones – devices that let you talk with a person on a similar device. Although humble, these were revolutionary, but it was only a matter of time before the world realized they had the potential to be so much more. With the advancement of technology, they were soon upgraded with better features and more usability.

One of the revolutionary advancements was the major upgrade to the Input System. In the vast majority of modern phones, physical buttons have been replaced with touchscreens, which are far more efficient and practical. We already make use of touchscreens almost everywhere, aside from smartphones, such as in elevators, ATM machines, cash counters, etc.

 

The only problem is that we don’t understand much of what goes on behind that ‘black mirror’. Our knowledge about touchscreens isn’t any more developed than a toddler – we’re fascinated by them and rarely ask questions… until now.

There are basically two types of touchscreens:

Perimeter-Based Touchscreen

These touchscreens have emitters embedded in the phones that emit waves. The interference in the wave pattern is registered as an input. There is no need for actual contact in order to detect an input; even hovering works. The waves can be infrared light waves or ultrasonic sound waves, which are similar in concept, but differ in effectiveness and accuracy. The wave setup has no metallic layers on the screen, allowing for 100% light through output and perfect image clarity.

Overlay-Based Touchscreens

These touchscreens have sensors embedded under the glass layer, so actual contact with the screen is necessary for registering input. Overlay-based touchscreens are more popular because of their low cost and higher durability. There are two types of Overlay-based touchscreens that are used in your phones and other handheld devices.

Resistive Touchscreens

Resistive Touchscreens

The resistive system works as a result of the interaction between two layers – the resistive layer and the conductive layer. The resistive layer is at the top, followed by the conductive layer, then the glass protector, and finally the display screen. The resistive layer is separated from the conductive layer by small spherical spacers. When you press the resistive layer, it actually bends and touches the conductive layer. The conductive layer then sends a current originating from this point of contact, while the processor in the phone uses this current to figure out the location of the point. Resistive screens are very durable and accurate, but not too efficient. These are used in places where accuracy is a priority over speed of use, such as in an ATM or cash-counter.

Capacitive Touch Screens

The capacitive system, on the other hand, does not have flexible screens, but instead utilizes the conductive nature of our skin. These touchscreens consist of a matrix of electrical circuits arranged on two similar, but perpendicular films that are thinner than a human hair. These layers have low-voltage current flowing through them, which gets transferred to our fingertips upon touch. The voltage drop due to this loss of charge is detected by four electrodes located at the four corners of your phone. Using the voltage drop data, the processor finds out the exact location of the input.

With the use of four electrodes and two conducting layers, unlike in resistive systems, it is possible to register slide input, as well as simultaneous multiple touches. The capacitive system transmits 90% of the light from the monitor, whereas the resistive system only transmits 75%. Due to this basic difference, capacitive surfaces reflect less ambient light, making it easier to see the screen.

Ambient light reflection can make it difficult to read

Another area in which the systems differ is in what registers as a touch event. A resistive system registers a touch as long as the two layers make contact, which means that it doesn’t matter if you touch the screen with your finger or a rubber ball. A capacitive system, on the other hand, must have a conductive input, usually your finger, in order to successfully register a touch.

All of these touchscreen technologies can also be integrated on top of a non-touch-based system, like an ordinary LCD that is converted into an Open Frame Touch Monitor.

Although this touchscreen technology was invented in the 1960s, high-end phones still use the basic concept developed back then. Some would say that we need an upgrade to newer tech.

Disney Research is currently developing a touchscreen technology called ‘TeslaTouch’. This aims to provide the user with hap-tic feedback and lets the touchscreen interact with the user. Voltage on the screen due to the conducting finger could be oscillated to control the friction between the screen and the finger. This could provide the user with the feeling of texture, or the user could find heavy files more difficult to drag than lighter ones! The future is going to be quite an amazing place!