Hello. Quick yet complicated question… How can the universe be "flat" if gravity curves spacetime?
Well, to be honest, I do not fully understand it, it’s hard to imagine because we live in a 3D universe (three spatial dimensions plus a temporal dimension), so when we say that the universe is flat, it is not in the same sense that a piece of paper is flat, but it means that geometry of the universe is such that the parallel lines never intersect, the angles in a triangle will always add up to 180 degrees, and the cube corners will always make right angles.
If Ω = 1, the universe is flat
If Ω > 1, there is positive curvature
if Ω < 1 there is negative curvature
And also in relation to curvature. When we see a “ simulation ” of the curvature in the space-time fabric, it is always shown in 2D, but this is just a simple way to demonstrate, in a 3D universe the visualization is a bit different and more complicated to understand.
Hey, nice Tumblr you got here! I'm just curious about what you think you would experience if you were to survive the "fall" into a black hole? I personally love hearing different thoughts, cause nobody really knows.
Well, that’s an interesting subject. To begin with, I think it would be practically impossible to survive a fall in a black hole, even though you could barely get “close” to one. Black holes distort the space-time fabric to a point of singularity, and the laws of physics we know “they break” to that limit. In fact, I think we have a lot to learn about them… Among some examples (as seen by an outside observer), we can say that when you fall into a black hole, you would be falling at an altissima velocity. Time seems to run slowly, (this also applies to the gravitational field. For example, because of the gravitational field of the earth, time passes slower here than in space, now imagine this in a black hole). When falling into a black hole, you would be “ spaghettification ” ought to the gravitational force be stronger on your feet than on your head.
In addition, there are some theories that black holes could generate other universes, others say that black holes would have links like “wormholes”, and that we could travel through them faster than the speed of light.
However, it is still a subject to discuss, and it would be difficult to see or prove, there are some who say that this connection from one point of space to another, the wormholes, due to entropy, would be unstable, and we would have a very short time to travel between they. Well, I do not know much about it, for me this is very complex hahaha, I tried to explain what little I know, and some explanations may be wrong … 🙂
how close of the sun would i need to be in order to get incinerated?
Honestly, I do not know what the limit is. But the approximation with its star, can provide some extreme cases. Due to being so close to its star, some planets have their “ locked ” orbit and always have the same face facing star. Some of these planets may orbit their stars in just a few days, much closer than the orbit of Mercury. Because of this, its atmosphere can evaporate by the intense radiation and winds blown by the star. Some exoplanets lose part of their atmosphere, and bear a resemblance to comets.
However, in extreme cases it is expected to completely evaporate the planet. As seen in the above gif, it shows the star system: a blue star KELT-9 and its planet KELT-9b. The KELT-9b exoplanet is so close to its star that its temperature is over 7,800 degrees Fahrenheit (4,600 Kelvin), it is a planet warmer than most stars.
Is there a reason the planets closest to earth are around it's size, mercury is tiny, and the planets farther out are massive gas giants? Does it tell us things about how the solar system formed? What was our solar system like, before it was really a "solar system"?
Well, the solar system started from the gravitational collapse of a molecular cloud of gas and dust caused by some star that passed close or shock waves from a supernova. Most of the collected mass was collected in the center, forming the star of our solar system, the Sun, while the rest flattened into a protoplanetary disk from which the planets and all other bodies of the solar system formed.
At the beginning of the formation of the solar system the temperature was high. The young Sun blew the gas that contained there, to where the gaseous planets are now located. So, this allowed them to collect enough mass to capture very light elements such as hydrogen and helium, which allowed them to grow to such large sizes. However, some extrasolar systems have “hot Jupiteres” orbiting near their star. Maybe, they form far beyond the frost line, and eventually migrate closer if their star. In another hypothesis, the nuclei of these hot Jupiteres began as more common super-Earths that joined their envelopes of gas in their present places, becoming gaseous giants.
I was learning about Saturn, and saw a picture of some of it's moons? They were oddly shaped and oblong, instead of perfectly spherical. Why would they be shaped that way? And does gravity warp matter, like on the planets, so that it's spherical? Could it warp in other ways? P.S. I really love this blog!! Informative and awesome 🚀✨
The tiny moons of Saturn are actually possible asteroids captured by the planet’s strong gravitational field. They are small, therefore, it does not have enough mass so that gravity molds it, and leaves them round, others are fragments of a greater celestial body. Thank you.
Do you think that once Smith's Cloud collides with the Milky Way, it will survive the collision to resuscitate the formation of stars in our dying (or possibly dead) Galaxy?
Very interesting it.
Although, really, I do not know for sure, but possibly its collision can generate a new explosion of star formation, although it may take millions of years for this to happen.
Smith’s cloud is a cloud of hydrogen and high speed, it is expected that it will collide with the Perseus arm of our galaxy. The impact will compress gas clouds on that spiral arm, causing a brilliant burst of star formation.
But it offers no danger, for, however large (10 000 or 11 000light-years), it is very small compared to the Milky Way.
This is a simple and solved case. The problem is that there are people who want to draw attention to themselves, and end up inventing these things.
There are several earth images taken from space to prove this.
The Blue Marble photograph of Earth, taken during the Apollo 17lunar mission in 1972. Credit: NASA
The crescent Earth rises above the lunar horizon in this spectacular photograph taken from the Apollo 17 spacecraft in lunar orbit during final lunar landing mission in the Apollo program. Credit: NASA
Apollo 11 astronauts took this photo of Earth on July 20, 1969. Credit: NASA
The possibility of the spherical earth was already predicted by ancient Greek philosophers, such as Pythagoras and Aristotle.
They cited simple observations, such as the changing position of stars as you travel north or south, the sinking of ships below the horizon, and the shape of the moon.
Despite this, there is other evidence that proves that the earth is not flat, like the lunar eclipse.
You can see the shadow of the Earth crossing the face of the Moon, and the shape of the shadow is curved because the Earth is spherical.
We can also mention the existence of time zones and several other aspects that prove that the earth is spherical. I do not think I need to put them all here.
Despite all this, look at the other planets (the largest moons, stars, etc.) all are round. This is because of the force of gravity.
I will use our solar system as an example. When our Solar System was forming, gravity gathered billions of pieces of gas and dust into clumps which grew larger and larger to become the planets. The gravity of a planet pulls equally from all sides. Gravity pulls from the center to the edges like the spokes of a bicycle wheel. This makes the general shape of a planet a sphere, which is a three-dimensional circle.
Other celestial bodies, comets and asteroids have irregular shapes because they do not have enough mass for gravity to mold them and leave them round.
So there is no reason why the force of gravity works for all other planets and does not work for our planet, leaving it flat. (more)
Unlike the Earth, Mercury’s surface is made up of just one continental plate covering the entire planet, as Mercury’s interior is slowly cooling it also shrinks and the total volume of mercury shrinks.
If all the galaxies are expanding away from each other, doesn't that mean they should be going in several different directions at the same time?
Basically, however, it turns out that galaxies are actually concentrated in clusters and super clusters of galaxies, and by that order of magnitude they are actually moving away from one another. But for galaxies that are close enough to each other, gravity overcomes the expansion, and both collide. For example the future collision of our Galaxy with Andromeda.