Big Bang. Everything was superimposed in one spot. Then there was a huge explosion and everything started to drift apart. Then there were stars, the world was formed, life was born, right? I wish life were that easy, Romeo.
The Big Bang did not occur at any particular point. It’s true that the galaxies are getting further and further apart, but it’s wrong that they overlapped in one spot before. Well, whatever you say is true, it is true that the big bang was everywhere at the same time and with the same intensity.
Before, there were no stars or galaxies. What existed was gas and dark matter. The statement that all objects in the universe are moving away from each other is among the mistakes we think we know. To give the simplest example, we approach each other to shake the hand of Andromeda, the galaxy closest to us. The universe has not continued to expand at an accelerating rate since the big bang. There is also a period when the expansion rate of the universe decreases. Then he changed gear and started to accelerate.
Einstein fails!
Einstein’s equations described a static universe. However, these equations were quadratic, indicating that they did not have a single solution. After this process, a great race started to find the right result. Physicists and mathematicians were solving equations adding new perspectives. Of course, those who were jealous of Einstein’s popularity were going crazy. Those who claim that the equations are wrong, and even those who claim these equations, are floundering around.
Willem de Sitter approached these equations differently than Einstein. His equations managed to subtract zero while preserving the cosmological constant. However, Einstein never thought that there would be a model with zero density, thanks to the cosmological constant he added to the equation. This result obtained by Sitter symbolizes the existence of energy in the void (that is, at zero density).
Considering the energy of zero density and the pressure of the universe, it can be thought that the universe should expand. It was thought about… In 1929, Uncle Edwin Hubble examined the spectrum of celestial bodies and observed the red shift. In other words, it was observationally proven in 1929 that the universe was expanding. Don’t worry, everyone can make mistakes. Despite those who are happy about this event, let’s take this opportunity to remember Einstein with respect.
Redshift?
Let’s look at that simple thing called redshift and Doppler Shift. I think it would be better if we follow the example given by most people for the Doppler Effect (Unless the menstruation is interrupted!).
You heard the screeching sound of an ambulance siren. If that ambulance is right behind you and you’re stuck in traffic, you’ll probably selfishly rejoice. As you know, you will arrive at your destination 1-2 minutes early. It’s a huge event.
Hear the sound of this ambulance in your ears now. As the ambulance approaches you, its sound gets louder, right? (If your answer is no, go near a hospital right now and observe!) Likewise, it should thicken as it moves away from you. This is what we call the Doppler Shift. Those who don’t know how objects move away from us with this understand, right? I did not understand too.
The same phenomenon is observed in light as in sound. As the sound thins and thickens, it shows a shift in light. As objects move away from us, their frequencies decrease, and if they get closer, they increase. Wavelength changes in the opposite way. If the frequency of an object decreases and moves away from us, a red shift is observed in the spectrum of the light it emits. I likened it to cars to keep it in my mind. If a car overtakes you and starts to drive away, you’ll see the red brake lights.
Let’s think about it this way. Think of frequency as a flexible spring (let it be huge). Let’s connect two galaxies with this arc. If galaxies move away from each other, this spring of ours gets stretched. So our wavelength increases. The thing is just that.
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