Three centuries after Newton's death, he still stopped us from heading to the stars.
Or at least his laws of physics are like this.
Keep in mind that in the summer, astronomers hardly see the huge space rock that passes through our neighborhood, called Oumuamua;
The rock is dark spots under the black sky, and the telescope only finds it when it flies back to the edge of the solar system, presumably further away.
However, at a brief moment in early November, some nerds at Harvard University saw it accelerate without business and wanted to know: If today is among those who study these things, this is an alien ship consensus: it is almost certain that this is not.
But it makes everyone talk about whether aliens from another solar system can fly here.
Or what humans need to fly to a distant inhabited planet.
It was time for Newton to lead everyone down to earth.
We asked some astronomers.
"We believe that every star in our galaxy has a planetary system," said Paul Delaney of the University of York . ".
This belief is the result of years of observation, especially the Kepler space telescope launched in 2009.
About 15 to 20 of these planets can sustain life, which means tens of billions on Earth-
Like the planets in the galaxy
Geography, however, hindered the process.
The problem is distance.
There are 11 stars about 10 light years from Earth. (
Light years are the distance light travels in one year or nearly nine years.
5 trillion kilometers. )
The nearest distance is over 4 light years, so it will be a long trip.
"At best it will take a few years for you to travel between the stars, if you are close to the speed of light," Delaney said . ".
Light travels about 300,000 kilometers per second.
What is needed to speed up the spacecraft "a lot and a lot of energy.
"We don't have anything to do that," he said . ". Blame Newton.
First, his first law of motion: any object has inertia;
It only accelerates when the external force works on it.
Add some Newton physics: the more mass an object has, the more force it needs to accelerate it.
Even "space chips" or wafers --
The size space detectors weighing dozens of grams need more energy than we know to achieve the speed at which they are brought to the stars in a reasonable amount of time.
Don't forget the theory of relativity, "Delaney said . "
"The closer you get to the speed of light, the greater the mass of your inertia, which means more energy is needed.
"We really have no choice (for)
Large objects are accelerated to a very fast speed, allowing them to travel through interstellar distances.
"Space Travel" is not difficult if you are willing to wait.
If you want to do this in the life of Homo sapiens, it's a lot harder, "said Seth Shostak, a senior astronomers looking for alien intelligence (SETI)in California.
A typical NASA Mars probe, if fired from the nearest star, "it will take about 75,000 years to get here (and)
By then, your own society may be so different that you have completely forgotten to do it.
To send a ship to a nearby star in a century, "you're talking about energy consumption, which is equivalent to the use of Canada for centuries.
Still, Delaney and others are excited to learn about the Oumuamua, "From the moment you say 'startourists', even if it could be a stone.
"We all have 1. 1 wishful thinking," Delaney said . ".
But there is no evidence yet.
But he's not looking for an alien.
Instead, he sees the big stone as a special delivery of building materials that make another solar system.
At the same time, the bigger question for Shostak is: why do aliens pay attention to the Earth, not to mention traveling here, "because, if they are so far away from the earth, what do they know about the Earth ", only to know that there is oxygen in our atmosphere, so we have some kind of life. Radio signals —
Especially the airport radar, it is a very good frequency to enter space.
It's been about 70 years since I went out.
Most of the universe has not received these signals yet.
However, Xiao Stark still believes in alien life somewhere.
He calculated about trillions of planets in the Milky Way, the Milky Way, and other trillions of galaxies. He believed that the Earth needed a miracle to become the only place with life. He did not believe in miracles.
At the same time, an astronomers at the Massachusetts Institute of Technology proposed
Watt's beam enters space as a "porch light" to let everyone know that the Earth is occupied.
James Clark estimates that anyone within 20,000 light years will notice.