Physics

Nasa James Webb space telescope discovered oldest galaxies in the universe

Published

1 year ago

15/01/2023

pouyan

First galaxies discovered by James Webb Telescope

NASA’s James Webb Space Telescope has revealed cosmic wonders, especially galaxies that are much older than previously thought.Scientists recently announced that they had identified objects that may be some of the first galaxies formed in the universe ; An amazing discovery was made thanks to James Webb, NASA’s new flagship space telescope. The discovery represents the first large sample of candidate galaxies far beyond the reach of the Hubble telescope, said Haojing Yan, an astronomer at the University of Missouri and author of the new study, at a press conference at the recent meeting of the American Astronomical Society.

The Universe oldest galaxies discovered by the James Webb Telescope

With more accuracy and sensitivity, the James Webb telescope can see the depths of space and older times better than Hubble. In the new catalog of 87 galaxies observed by James Webb, some are even as old as 13.6 billion years ago, just 200 million years after the Big Bang. At this time, the galaxies emitted the light that we see today; However, even if these gas, dust, and star systems exist today, they have changed significantly.

Although scientists have observed other distant galaxies that date back to the universe’s youth, Yan’s group’s discoveries could break all previous records by a few hundred million years. However, at this stage, they still classify their discoveries as “candidate galaxies”; Because the date of birth of the mentioned galaxies needs confirmation.

Galaxy dating can be difficult due to its “redshift.” The redshift shows how much the light emitted from the galaxy is drawn towards the long red wavelengths, and thus, it proves how fast the galaxy in question is moving away from us in the expanding universe. Astronomers can therefore calculate the galaxy’s distance from Earth, or more precisely, the distance photons from stars travel at the speed of light to reach a near-Earth telescope like James Webb’s.

How their age calculated?

The light from the stars in the most distant galaxy in the cluster was probably emitted 13.6 billion years ago, right after the young galaxy formed. The new estimated distances must be confirmed based on color spectra, which means measuring the galaxy’s light across the electromagnetic spectrum and determining its unique properties. However, Ian believes that many of them date back to the universe’s early days.

Using James Webb’s Near Infrared Camera (NIRCam), Yan’s group photographed the galaxies above at six near-infrared wavelengths. The researchers used the standard “dropout” method to estimate the distance of the galaxies. Hydrogen gas around galaxies absorbs light in a specific wavelength; Therefore, wavelengths at which mass is detectable or undetectable can help measure distance. The 87 candidate galaxies often appear as blobs that are only detectable at longer near-infrared wavelengths with NIRCam. Thus, we can conclude that these galaxies are very distant and old.

However, some galaxies may be much closer than thought and not as old as we think. For example, their light may be too faint to detect at certain wavelengths. We can’t say for sure until Yan and his team collect more detailed data.

Many astronomers are excited to use the James Webb Telescope to study early galaxies. Each galaxy needs a lot of time to reach a unique shape. Many of them look like the Spanish sombrero, So their inner part is bellied, and a thin disk is located on the other side. While some others only have a convex and circular appearance. Astronomers previously thought that few galaxies had disks, But with the advent of the James Webb telescope, many facts were revealed.

Now some astronomers, such as Jehan Karteltep, an astrophysicist at the Rochester Institute of Technology, hypothesize that early galaxies could have complex structures like the massive spiral arms of the Milky Way. Cartletep is part of the scientific investigation of early cosmic evolution and presented his paper at the Astronomy Conference. He adds:

James Webb’s increased resolution allows for clearer structure observations, and NIRCam’s increased sensitivity allows us to observe low-light features we couldn’t see before.

Kartaltop and his team examined 850 galaxies with an infrared web camera. These galaxies are between 11.5 and 13 billion years old. His group found that approximately 40% of these galaxies have disks. Another group of astronomers used James Webb’s near-infrared spectrometer, which measures light intensity over a range of wavelengths. They discovered three objects, roughly 700 million years after the Big Bang, that resemble small pea-sized galaxies.

James Rhodes, an astrophysicist at NASA’s Goddard Space Flight Center, published the research paper last week. Their research shows that 700 million years after the formation of the universe, these compact galaxies, thought to be young and forming stars, were probably very common. He says that today we see similar galaxies in nearby space, But pea galaxies are much rarer in our cosmic backyard.

Via: Wired

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Physics

Recording the first X-ray image of an atom with a “quantum needle”

Published

11 months ago

05/06/2023

pouyan

Recording the first X-ray image of an atom with a “quantum needle”. For the first time, Ohio University scientists have managed to record the first X-ray image of an atom using a quantum needle.

Recording the first X-ray image of an atom with a “quantum needle”

A group of researchers led by Professor Saw Wai Hla from Ohio University’s School of Physics has captured the first X-ray image of an atom, allowing scientists to study materials and their chemical states with greater clarity than ever before.

Taking pictures of atoms is nothing new. Scientists have been able to do this for years with scanning probe microscopes.

Scanning probe microscopes use a sharp, electrically charged, atomically charged needle tip to probe the surfaces of materials at the nanoscale, thanks to quantum mechanical interactions that cause electrons to flow between the tip and atoms on the surface. Scanning probe microscopes (SPM: Scanning probe microscope) use a probe that moves on the sample to check the surface of the samples. By using these microscopes, in addition to surface topography, it is possible to obtain information about friction, magnetization, thermal properties, and elasticity of the surface, which cannot be obtained using other methods. In this microscope, the tip of a healthy and ideal probe is very sharp, so that only one atom can fit in its tip. Therefore, it has a very high sensitivity, and due to its very small dimensions, it can detect the smallest deviations or heights on the surface of the sample in the range of nanometers, and using the equipment and software in the device, the obtained data can be displayed as an image on the screen.

Many scanning probe microscopes can take a large number of images simultaneously. The method of using these interactions to obtain an image is generally called a “mode”. Resolution varies somewhat with each different technique, but some techniques achieve impressive atomic resolution. This is largely due to the fact that electrical pressure actuators can execute motion with precision at the atomic level, or even better, at the electron level.

But the constant problem in using scanning probe microscopes is the resolution of these images. Not only do scientists want to see atoms, but they also want to know about their chemical state on a single-atom scale, and that requires the use of X-rays, but current X-ray-based devices can only measure up to one autogram, or one-millionth of a trillionth. Analyze the gram, which consists of about 10,000 atoms. That’s not much at the atomic level, but it’s still too much for scientists.

To overcome this problem, Ohio University researchers embedded iron and terbium atoms in a matrix of ring-shaped supermolecules. They then used a technique called synchrotron X-ray scanning tunneling microscopy (SX-STM), which combines the basic mechanics of a scanning probe microscope with X-rays produced by an atomic accelerator called a synchrotron.

This aggregation produces an X-ray spectrum that records how the X-rays are absorbed by the electrons mentioned at the surface of the nucleus.

“Atoms can be imaged normally with scanning probe microscopes, but without X-rays, you can’t tell what they’re made of,” says Professor High Law.

He added: “We can now precisely identify the type of a particular atom and we can simultaneously measure its chemical state.” Once we can do this, we can trace materials down to the size of an atom. This will have a huge impact on environmental science and medicine, and maybe even find a cure that can have a huge impact on humanity. This discovery will revolutionize the world.

This research was published in the journal Nature.

Physics

Water play in the space station is not just fun and games

Published

1 year ago

14/03/2023

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Water play in the space station is not just fun and games .ESA astronaut Samantha Cristoforti, who recently visited the International Space Station, poured liquids into the International Space Station to gather information for the design of fuel tanks.

Water play in the space station is not just fun and games

In this artice we’re going to read about why water play in the space station is not just fun and games .In an interview with Nature magazine, he said about his job: I am an astronaut of the European Space Agency. Last year, I spent five months—from late April to mid-October—on the International Space Station (ISS), with the last month as station commander. Before returning to the field, my team and I took some time to play with the water. Here, inside the International Space Station, I show how water behaves in zero gravity.

There are a few tricks you can use to make sure the water stays where you want it. Surface tension holds the water bubble together, and you can move it by gently pulling on it using a straw or blowing on it. If the bubble is small enough, you can drink it. We recycle all the water inside the spacecraft.

Weightlessness is not only exciting but also an opportunity to study fundamental physics. There is a lot of research on fluid dynamics in space stations. A study that I personally participated in deals with the loosening behavior of different types of liquids and mixtures of liquids and gases in containers. The results are very important for the design of fuel tanks, especially for space applications.

This photo was taken in the Japanese test module. It’s the largest single module on the ISS, so we often use it to talk to the media or school students. When we communicate with them, we use things like the balls behind my head that are models of the planets and the moon. The round thing behind me is the module airlock. We use it to deploy satellites as well as hardware like scanners for science experiments.

This was the second time I went to the International Space Station. I quickly adapt to the space and enjoy the feeling of weightlessness very much. It’s much harder for me to come back down to earth.

I don’t know when I will go there again. We’ll see how the US-led Artemis program to return humans to the moon evolves over the next decade. Maybe I will get another chance.

Cristoferti was a member of the Crew-4 mission carried out by SpaceX. At that time, he arrived at the space station with the “Dragon” capsule to begin his 6-month stay on April 27. It should be mentioned that the “Cro-4” mission was the second space flight of “Cristoforti”. He previously stayed on the space station from November 2014 to June 2015.

Physics

Why does time move forward?

Published

1 year ago

02/03/2023

pouyan

Why does time move forward? No matter how ambiguous we are about the phenomenon of time, we agree on one thing, and that is that time always moves forward.

Why does time move forward?

Recently, a group in Australia has investigated the category of moving time forward and how it occurs. Before this, it was thought to be one of the fundamental principles of the natural world, but apparently there is a more important reason for this.

We all know that time only moves forward. No matter how many attempts have been made to change it, we know that broken glass will never repair itself and people will never be young again after aging. There are many hypotheses for the cause of this phenomenon, but for a long time, it has been thought that this one-way movement is one of the fundamental and integral parts of nature.

But based on new research conducted by Joan Vaccaro of Griffith University in Australia, it is said that this is not the main issue, and there is probably a deeper and more solid reason for time to move forward. In other words, it can be said that there must be a very careful difference between two different time directions. These two directions are actually the past and the future, and there is a factor that always leads us to the future and the opposite never happens.

Let’s back up for a second. It seems that this category is one of the most exciting and unimaginable aspects of physics. The mystery of time seems ambiguous because the forward movement of time is important in human life. But if we look at them individually at the atomic and molecular scale, then the movement of time forward or backward will not make much of a difference for these particles, and the particles will continue to behave regardless of the movement of time forward or backward.

We should keep in mind that our main discussion here is not about space, because you shouldn’t expect that moving objects in space won’t change their location anyway. Therefore, scientists believed for a long time that there must be a basic reason for the expansion of the universe as time moves forward, and they did not imagine this for the category of space itself. This view is actually known as the asymmetry between space and time. The best example to express inconsistency is that the equations of the laws of motion and stability have inhomogeneous functions in time and space. Vaccaro says:

In the relationship between space and time, it is easier to understand and receive space; Because space is something that simply exists. But time is something that always pushes us forward.

His new plan states that it is possible that the two mentioned directions for time (forward and backward) are not the same at all. Vaccaro continues: Experiments conducted on subatomic particles in the last fifty years show that nature does not behave the same in dealing with these two directions of time. Among these, we can especially mention the subatomic particles called B and K mesons, which exhibit anomalous behaviors in terms of time direction.

K and B mesons are very small subatomic particles that cannot be examined without the help of some advanced tools. But the evidence of their different behavior according to the time direction effective on them shows that the reason for this difference, instead of being related to a fundamental part of nature’s behavior, may be due to the direction in which we are moving in time. We are walking. Vaccaro explains in this context: As we move forward in time, there will always be some backward bounce, like the effects of motional instability, and in fact, this backward motion is what I intend to measure using the B and K mesons.

To carry out this research, Ms. Vaccaro rewrote the equations of quantum mechanics, taking into account that the nature of time will not be the same in two directions, and the results showed that the calculations performed can accurately explain the mechanism of our world. Vaccaro said about this: When we included this complex behavior in the model of the universe, we realized that the universe moves from a fixed state in one moment to moment-to-moment and continuous changes. In other words, this difference in the two directions of time seems to be the reason for forcing the universe to move forward.

If this issue is proven, it will mean that we have to rethink and revise our understanding and acceptance of the category of time passage and the equations affected by it. But on the other hand, this achievement may lead to new insights and findings about the more strange aspects of time. Vaccaro said in the end: Understanding how time passes and evolves brings us to a completely new perspective on the natural foundations of the phenomenon of time itself. Also, in this way, we may be able to get a better understanding and reception of amazing and exciting ideas such as traveling to the past.

Vaccaro’s calculations have been published in the Journal of Physical and Mathematical Engineering Sciences.