What exactly does "Mach" mean, and how many kilometers can you fly at Mach 15 for one hour?

Mach

Mach is a unit of physics that indicates the ratio of the speed of an object to the speed of sound, and this speed of sound is the speed of sound propagation in the air at 340 m/s.

For example, Mach 1 is the speed of sound, and Mach 2 is twice the speed of sound.

Of course, there are cases where Mach 1 is not necessarily 340m/s because the speed of sound in the air has a relationship with pressure and temperature.

When using Mach as a unit, it is important to specify the conditions, such as standard atmospheric pressure.

Mach is often used in aviatbecausethat before an aircraft breaks the speed of sound, there is always a sound barrier, also known as the speed of sound wall.

At that time, when conducting experiments on aircraft, engineers found that the closer the speed of the aircraft was to the speed of sound, then the more drag it would experience.

When the speed of sound, it will be like hitting a wall, hence the name Sonic Wall, the physical name of the sound barrier.

If the speed exceeds the speed of sound, the aircraft becomes less controllable and less stable. More importantly, the aircraft itself will be damaged.

Initially, engineers believed that this sound barrier can not break through, because at that time the material can not withstand the huge drag brought about by the speed of sound flight, often end up falling apart.

However, with the improvement of material technology, supersonic speed is no longer a dream.

In 1947, the U.S. X-1 fighter jet achieved supersonic flight, after which the speed of the fighter jet was improved, and Mach gradually became a common unit in the aerospace field.

The birth of the unit Mach predates the event of human achievement of supersonic flight, and it was proposed by physicist Ernst Mach.

It was proposed for use by the physics community in 1929 as an expression of speed.

When the speed reaches Mach 2.5, the limit of aluminum alloy material is reached and any faster will result in the disintegration of the aircraft.

If the speed reaches Mach 3, the entire aircraft itself will turn into a sizzling fireball because of friction with the air.

The supersonic flight will also appear sonic boom, producing a huge noise, so we often see the fighter jet flight training, are away from the city.

The fastest aircraft

The fastest human aircraft is the U.S. X-43 fighter jet, the speed reached Mach 9.8, from the East Coast of the United States to the West Coast in just half an hour.

It would take more than 3 hours to fly around the earth in such an aircraft.

If an aircraft flies at Mach 15, it can complete its round-the-world flight in just over 2 hours, as Mach 15 indicates a speed of 4080m/s, which translates to 18,376.2km/h.

However, Mach 15 is just a scientist's prediction, the current limit or Mach 9.8.

Some people are curious, why not use how many kilometers per hour, or how many seconds we are all familiar with, but use Mach to express the speed?

This is because Mach is the ratio of speed to the speed of sound, so the expression can be more straightforward to see the relationship between speed and speed of sound, and more convenient to quickly calculate some of the data needed in the process, such as sonic boom, damping, etc.

But even if the Mach 15 aircraft, but only on the Earth fly flight, want to travel in space, its speed is completely insufficient!

Speaking of which many people may think that the speed of a rocket launch will be greater than the fastest aircraft.

The largest rocket thrusters are only about Mach 7, and ordinary rockets are only Mach 2 point a few.

When we launch a rocket on Earth, it doesn't start out at the first cosmic speed either but is gradually accelerated during liftoff to reach it.

This is because the launch direction of the rocket differs from that of the X-43 in that the rocket takes off vertically from the ground, while the aircraft flies horizontally from the ground.

The former weighs much more than the latter, and it has to overcome its gravity while overcoming air resistance.

And the range of the rocket is too much stronger than the aircraft and can rely on the late speed, but the combat aircraft will have to reach the limit of speed in a short period, and the range is relatively weak.

But after all, is said and done, in front of the speed of light, any Mach aircraft, are younger brothers.

To say that the speed of the world's boss, the speed of light is the eternal drop of God, it is currently the largest speed known to man.

Our Earth's unit of length in the universe is simply not enough, so there are light years.

According to Einstein's theory of relativity, if the speed of an object reaches the speed of light, space-time will be distorted, then it can go back in time.

Yet the speed of light is out of reach for humans, who can only use gas pedals to bring particles infinitely close to the speed of light but cannot reach or exceed it.

For it was still Einstein, who deduced that the mass of an object becomes infinite when its speed is equal to the speed of light.

Yes, the mass of matter changes according to its speed, but only in a macroscopic environment, this change is imperceptible because the current macroscopic speed of humans is too small.

Therefore, many scientists believe that FTL flight is impossible to achieve, because it represents a direct collapse of matter, and theoretically there will be no infinite mass.

Moreover, even if FTL is reached, is the distance of the universe that easy to reach?

Assuming that a spaceship travels at the speed of light, the event for it to travel to our nearest neighbor, Proxima, is 4.3 years.

And our galaxy is 100,000 light years in diameter, which is 100,000 years for a speed-of-light ship, and a person who is in it will not live to see that day unless they are immortalized.

So you can see that even the maximum speed known cannot span the sea of stars in the universe.

A physical quantity like Mach cannot be used in the universe because the universe is a vacuum and there is no such thing as the speed of sound.

Spanning Space

So is there a faster-than-light existence in the universe? Scientists believe there is, it's just that humans can't discover it right now.

There is a good chance that we do not know as much about the universe as we think we do.

To complete interstellar travel, it is not necessary to let the object reach the speed of light, even the ordinary speed of the vehicle, but also can do, but it requires certain "tools".

There are two kinds of holes in the universe, one is called a black hole, which we are familiar with, and is what will be sucked in, light is no exception.

The other hole is called a wormhole, which is a hypothesis developed by Albert Einstein when he was studying the gravitational field.

Einstein believed that mass would trigger depression in the surrounding space, forming certain fields, and he believed that these fields would be connected through a kind of bridge.

Matter can reach another space through this bridge, which is the wormhole, also called the "Einstein-Rosen bridge".

This is like when there is no bridge, you have to cross the river by boat, not only slow but also affected by the speed of the current, and the final landing place will deviate from the original plan.

But if you build a bridge over the river, then you can go directly to the other side of the river, even if the river at this time is a monstrous wave.

In addition to wormholes, another technology is very exciting for scientists, and that is space folding.

We all know that the shortest line segment is between two points, but if we fold the line segment, such a distance will be directly halved.

Similarly, a certain face of our universe is regarded as a piece of paper, and the Earth is a point on the paper, fold the paper, and the distance between the Earth and other planets will be shortened.

Fold it a few more times and you will get a distance that is acceptable for a human craft to achieve to the next galaxy, even if it is not an FTL spacecraft.

Space folding

Of course, for an aircraft on Earth, the speed of light is too far away, and Mach is sufficient for human flight on Earth.