Connect with us

# How to Easily Locate the Accelerometer in an iPhone

Everyone should probably know that I’m obsessed with both physics and smart phones. If I can use my phone for a physics experiment, I’m good to go. That’s exactly what I am going to do right now—use some physics to find the location of the accelerometer in the iPhone 7.

Your smart phone has a bunch of sensors in it. One of the most common is the accelerometer. It’s basically a super tiny mass connected with springs (not actual springs). When the phone accelerates in a particular direction, some of these springs will get compressed in order to make the tiny test mass also accelerate. The accelerometer measures this spring compression and uses that to determine the acceleration of the phone. With that, it will know if it is facing up or down. It also can estimate how far you move and use this along with the camera to find out where real world objects are, using ARKit.

So, we know there is a sensor in the phone—but where is it located? I’m not going to take apart my phone; everyone knows I’ll never get it back together after that. Instead, I will find out the location by moving the phone in a circular path. Yes, moving in a circle is a type of acceleration.

Of course you already knew that circular motion was a type of acceleration. Yes, you knew this because you have been in car (you have probably been in a car). It turns out that the human body can also feel accelerations—although we sometimes confuse these accelerations with gravitational forces, but we can still feel them. If you are sitting in a car seat and the vehicle speeds up, it accelerates and you can feel that. Now if that car is turning in a circle, you can also feel it. That turning car is accelerating—even if it travels at a constant speed.

If you want to really understand why circular motion is a type of acceleration, you need to start with the definition of acceleration.

Here the Δ means “change in”. So the acceleration is the change in velocity divided by the change in time—that is a rate. But here is the key point. Both the acceleration and velocity are vector quantities. This means that they depend on direction as well as magnitude. Since the velocity is a vector, you can have an acceleration just by changing the direction of the velocity. Moving in a circle at a constant speed means there is indeed an acceleration.

If we have an object moving in a circle, the acceleration is pointed towards the center of the circle and depends on two things: the angular velocity (ω) and the circular radius (r). If you increase either of these values, the magnitude of the acceleration will also increase according to the following:

So perhaps you can see where this is going. If I move a phone around in a circle, I can measure both the acceleration and the angular velocity. From this, I can calculate the radius of the circle—which will be the distance from the center of the circle to the accelerometer. That shouldn’t be too difficult. Actually, I have done this experiment before but it was a slightly different setup.

Actually, you can do this yourself. Really, all you need a device that rotates the phone such that it moves in a circle with a constant radius. For me, I used this nice rotating platform.

Notice the addition of the ruler so that I can accurately measure the distance from the center of the circle to the bottom of the phone. I also put a small clamp at the end to prevent the phone from flinging off the platform. That would be bad.

The other thing you need is a way to measure both the angular velocity and the acceleration. Most phones have a type of gyroscope to measure rotations so that you can get both measurements with your phone. Although there are several apps to record sensor data on your phone, but I really like PhyPhox (for both Android and iOS).

Now we are all set. Start recording data and rotate the phone. As the angular velocity changes, so does the acceleration (since the radius is fixed). Since the acceleration is proportional to the square of the angular velocity, I can plot acceleration vs. ω22. It should look something like this (hopefully).

It seems to be linear—so that’s good. The slope of this line is 0.14138 meters with an intercept of 0.093 (rad/s)2 (that’s close to zero). That slope is the important part. It’s the distance from the center of the circle to the sensor. I recorded the distance of the bottom of the phone to the center with a radius of 0.09 meters. This means that the accelerometer is 5.1 centimeters above the bottom of the phone.

But wait! What about the side-to-side location? I can repeat the experiment with the side of the phone facing the center of the circle. Here is the data for that run.

In this case, I had the screen facing down with the “sleep” button side of the phone facing the center of the circle at a radius of 15.9 cm. The slope of the line above is 17.7 cm. That means the sensor is 1.8 cm from the side. OK, this is technically wrong, but I’m going to use it anyway. The 17.7 cm is actually the radial distance to the sensor. This will only give me the distance from the side of phone if the sensor was half way from the top of the phone. Oh well, this will be close enough.

So here is a diagram of my iPhone (looking at it from the back).

Pretty sure that’s where the sensor is located. Now I just need to take apart my phone to verify this result. Oh wait. I’m not going to do that.

Read More On This At Science Latest

# New Physics: Mysterious radiation pointed to the verge of discovering a “ghost” particle that makes up dark matter

Photo: Daniel Molybdenum, NASA's Goddard Space Flight Center

Physicists at the Lawrence Berkeley National Laboratory in the United States have found that the mysterious high-energy radiation emitted from the vicinity of a group of neutron stars may indicate the existence of axions – not yet discovered particles within the framework of New Physics, the search for which has been going on since 1977. It is assumed that special types of axions form dark matter. This is reported in an article published in the journal Physical Review Letters. The research is summarized in a press release on Phys.org.

It is believed that axions can form in the core of neutron stars and transform into photons in the presence of a powerful magnetic field. To detect the electromagnetic radiation associated with axions, you need to find stars that do not emit radiation at different wavelengths that can mask the desired signal.

These objects include the Magnificent Seven neutron stars that emit only X-ray and ultraviolet radiation. They are located at a distance of 200-500 parsecs from the Earth.

The researchers ruled out the scenario that the excess X-rays produced by the Magnificent Seven are actually emitted by other, more distant objects. These sources would be found in datasets from the XMM-Newton and Chandra X-ray space telescopes.

The extra X-rays likely originate from axions hitting an extremely strong electromagnetic field billions of times stronger than the magnetic fields that could be created on Earth, the scientists concluded. The axions themselves resemble neutrinos in their properties, since both have insignificant masses and rarely and weakly interact with matter.

The axion is currently viewed as the most promising candidate for dark matter particles, since another hypothetical candidate, the massive WIMP particle, has gone unnoticed in experiments aimed at detecting it.

In addition, there may be a whole family of axion-like particles that form dark matter, as suggested by string theory. If axions are found, it will prove that there is a whole new area of ​​physics outside the Standard Model describing the properties of all known particles.

To find out, the next step will be to study white dwarfs, which are not expected to emit X-rays.

“If we see an abundance of X-rays there too, our arguments will be pretty compelling,” said lead author Benjamin Safdie.

# The goal of human civilization is to create AI and disappear?

Various sources often talk about civilizations that lived long before us. They all developed, prospered for a while, and then disappeared in an incomprehensible way.

What is the reason for their decline, we probably will not know. All we can do is admire the remains of stone buildings, over which time has almost no power.

While looking for an answer, we somehow accidentally stumbled upon an interesting saying about the life of Japanese samurai: “A samurai has no goal, but a path.” In the end, the “path of the samurai” ended in what is known – death. The path of any civilization ended in the same way.

If you look at the issue through the prism of a samurai saying, then there is no point in looking for why and how civilization ended its existence. Probably, the process itself and its result are important here. But to whom is it important and what result does it expect?

## Mysterious director

Apparently, behind the curtains of this “ancient theater” there is a mysterious “director” who periodically makes necessary adjustments to the history of civilization.

To figure out what’s what, you need to look at current trends in science. Where does a person strive with such an irresistible desire to “play God.” This attracts him and at the same time frightens him, but in no way turns him away from the intended path. Most likely, artificial intelligence (AI) is the purpose of our civilization’s existence.

About 50 years ago it would have seemed nonsense, but to someone, perhaps even now. However, if you trace the last 100 years of the life of our civilization, you get the feeling that most of the discoveries were given to mankind at the same time. A powerful leap has taken place in a hundred years. Why did it happen?

At the beginning of the last century, scientists recognized the existence of fields that have memory and the ability to store and transmit information. It is very likely that such or a similar field can be around the Earth and, more interesting, possess intelligence. Isn’t this the same “Director” hiding behind the screen of the “ancient theater”?

If this is so, then at a certain moment the “Director” gives the selected scientist “access” to certain knowledge (perhaps even in a dream, like Mendeleev), and another scientific breakthrough occurs in the world. Step by step, discovery after discovery, humanity is steadily moving towards the creation of AI. The trend is already well visible.

AI is probably the next “Babylon”, which will combine all the knowledge, culture and accumulated experience of civilization. In the future, the neural network will enter into a connection with the general information field and leave humanity without knowledge, technology, and even a spoken language. This will be the next decline of civilization. And the “Director” will receive another array of new data (experience) in order to start creating a new civilization.

If someone believes that past civilizations ended in large-scale conflicts, then most likely this is already the consequences of “turning off” AI.

## Co-founder of Skype talked about the threat of AI to humanity

One of the creators of the Skype internet call service, Jaan Ta

llinn, said that the development of artificial intelligence (AI) threatens humanity. According to him, humans face three key threats, but it is AI that should be feared most of all, the expert said.

Tallinn explained that at the moment, no one can predict what development AI will achieve in the next decades. In addition, the fact that scientists are creating artificial intelligence that can form a new AI without human intervention is also a cause for concern.

In addition, as the co-founder of the popular video calling service noted, the development of synthetic biology also causes concern. According to him, this direction in science allows the creation of artificial DNA sequences and biological systems that may not exist in nature.

Tallinn also drew attention to the fact that he fears we are entering an era of “unknown unknowns”, things that people are not even able to imagine right now.

# Volkswagen robot will autonomously charge cars: a working prototype presented

The renowned German car manufacturer announced a new development. This time, engineers have created a unique robot capable of autonomously charging electric vehicles.

For more than a year, specialists have been developing this project, but only now the concern was ready to demonstrate the first working prototype. The robot is ready to charge electric vehicles and has shown the high efficiency of this process.

It is called the Mobile Charging Robot, and experts have already compared it to the R2-D2 droid from Star Wars, including squeaks and clangs. Indeed, there is a similarity. Before implementing this idea, the engineers decided that robots should be allowed to charge cars parked in large residential complexes.

This will save their owners from leaving in order to find a gas station. Another advantage is that large parking lots and garages do not have to contain several expensive charging points for electric cars. The car company said in a press release that the robot works exclusively autonomously.

It independently controls and interacts with the vehicle being charged. It opens the cover of the charging socket and independently connects the power plug, then disconnects it. The robot looks like a trailer, which is a mobile energy storage.

It is capable of charging multiple electric vehicles at the same time. Despite the fact that the manufacturer confidently praises its concept, experts saw inefficiency in the fact that first it is necessary to charge the robot’s battery, which is then used to recharge electric cars.

Volkswagen Group Components CEO Thomas Schmall noted that creating an efficient charging infrastructure for the cars of the future is an important step in the company’s development.

Its engineers focus on finding solutions to avoid costly do-it-yourself measures. The mobile robot is only part of the concept that will continue to be developed.