For many, the word space has a variety of applications, from outer space to inner space. But what does that actually mean? Is space something physical or just an idea? And what about time? How does it relate to our lives and our universe? In this article, we’ll break down the definition of these two very important concepts that we can’t live without yet don’t often think about.
The Physics Behind Our Universe
To really understand space, you have to understand Einstein’s theory of relativity. You see, when we look out into space (and we’re viewing stars, galaxies or other objects), what we are actually seeing is their past. Why? Because that’s how long it takes for light (which travels at 186,000 miles per second) to reach us from these objects in our universe. The farther away an object is, the longer it takes for its light to travel here. That’s why we can only see a small part of our universe; everything else has already happened—we just haven’t seen it yet. And if you want to know more about time, watch our video on time dilation . It explains why time slows down as you approach the speed of light. We also discuss two different theories of gravity: general relativity and Newtonian gravity. So sit back, relax and learn some physics! The Big Bang Theory: When people think of space and time, they often think of one thing: the big bang. But what exactly was it? Well, there are many different theories about what caused our universe to expand outward after a sudden explosion. One popular hypothesis suggests that all matter in existence was once contained inside a singularity—an infinitely dense point where gravity reigns supreme.
Einstein’s Theory of Relativity
Relativity may be one of Einstein’s more popular theories, but it can often be a little hard to grasp. The basic idea behind relativity is that space and time are dependent on how we move through them, but relative only to each other. For example, if you were in an elevator with no windows and someone asked you what floor you were on, there would be no way for you to answer their question without first knowing where your elevator was going or coming from. But if you knew both where your elevator was going and coming from—and how fast it was moving—you could calculate your current location in relation to those points. This is because space and time aren’t absolute; they depend on our movements through them. In fact, according to relativity, there isn’t even such thing as absolute rest. It doesn’t matter whether you sit still in an empty room; you will always be moving at some speed through space-time. And though you might not feel like you’re moving, everything around you is constantly shifting too. This means that every object in your field of vision has moved since the last time you saw it. Even if nothing seems to have changed, light moves so quickly that something closer than a trillion miles away (the distance between Earth and Proxima Centauri) has shifted out of sight since we last looked at it!
The Big Bang Theory
According to most theoretical cosmologists, space and time emerged as part of a primordial event called the Big Bang. The Big Bang theory suggests that when we talk about space-time (which many physicists like to call simply spacetime), it makes sense to ask questions about how things were before it happened—just as we can ask how things were before Columbus set sail for America in 1492. But according to some theories, asking such questions is meaningless. In fact, these theories suggest there was no before—no moment at which there was no universe. Instead, everything just popped into existence with a big bang! These are known as eternal or no beginning models of our universe. A related idea is what has been dubbed the block universe by philosophers and others who study time and physics. This view suggests that past, present, and future all exist on equal footing within an unchanging four-dimensional block of spacetime. Some people think of time as a river flowing through this block; other people think of it more like an infinite collection of static snapshots, each one representing all possible states at any given moment in time. This model implies that there is no objective flow to time; rather, different observers will experience events occurring at different rates depending on their distance from those events.
Global Positioning Systems (GPS)
GPS relies on satellites, which follow a specific orbit. These satellites send signals to your GPS device (such as in your cell phone or car), giving it information about its position. Without satellites, there would be no GPS system, meaning that many of our modern conveniences—including cars—would cease to exist. Thankfully, these futuristic tools have existed for quite some time now. The United States began sending up satellites into orbit around 1960 for military purposes, but once GPS was created in 1973 by Dr. Bradford Parkinson, civilians could use them too. Today’s GPS devices are incredibly accurate; they’re so precise that you can use them to get turn-by-turn directions while driving down a city street! If you’ve ever had to drive somewhere new and gotten lost, it’s almost certain that you wished your cell phone had GPS capabilities. And if you haven’t had such an experience yet, don’t worry—you will someday soon.
The Second Law of Thermodynamics
This law describes a loss of energy, so it may not seem relevant to something as massive as space. But one thing that happens when you lose energy is that you heat up—and scientists can actually measure spatial temperature fluctuations! Just don’t call it heat; it’s blackbody radiation. This isn’t hot air; rather, these are photons (particles of light) that randomly bounce around in space until they hit an atom and get absorbed. The hotter an object is, the more radiation it gives off. In fact, all objects give off some level of blackbody radiation; even human beings emit infrared light from our bodies. If we were cold enough, we would glow in the dark! As a general rule, colder objects radiate less than warmer ones. So what does all of this have to do with time? Well, if your car breaks down at night on a deserted road, it will be colder than if you broke down during the day. Colder things move slower because there’s less energy inside them. A watch left out on a winter night will run slower because of its low temperature relative to daytime hours. It might be hard to wrap your head around how time moves slower in cold temperatures, but there’s no denying that clocks tend to run slow when they get cold and fast when they heat up.
