- How do we know we’re only observing 5% of the Universe?
One of the indications is that the dynamics of the visible Universe cannot be fully described without introducing two key components: Dark Matter and Dark Energy. To be in accordance with the laws of physics, these two elements must compose 95% of the Universe.
- Why does it matter if we’re not seeing all of the Universe?
The “Dark” components of the Universe might be made of something extraordinarily unexpected which could give us a better understanding of our Universe, its origin and its fate. It might also give us practical benefits – as it was the case with Einstein’s general relativity and the GPS navigation system – and improve our quality of life. And philosophically: one of the human attributes is curiosity. Asking questions and looking for answers is the reason why so many scientists are dedicated to unraveling the mysteries laying behind these 95%
- What are dark matter and dark energy and how are they different?
Although some theories exist regarding the nature of Dark matter and Dark energy, a lot more efforts need to be made. Dark Matter is expected to be responsible for the visible gravitational effects, e.g. galaxies rotation, while Dark Energy is believed to cause the accelerated expansion of the Universe, as if its components were repelled one from another.
- What is a “dark messenger”?
Here we speak of a particle or ensembles of particles that can be observed with the available tools and whose existence is the result or manifestation of the existence and properties of Dark Matter or Dark Energy.
- Why would “Dark messengers” travel in groups – why is this important?
A group of particles, according to some theoretical models, might be a Dark Messenger. And a group of particles, or better – widely distributed group, might produce a clear footprint that we can see with available tools. The footprint might be more clear if we look at it in a clever way – globally. A single particle (non-group) can be a Dark Messenger too, but we have a plenty of “standard” models explaining single particles. A group would be something truly new.
- Why would I want to know if my catch is part of a group?
As explained above, groups of particles would have a very distinguishable footprint and would therefore give us a much better idea of what we are dealing with.
- Will people be aware of my location?
First of all we do not request any of your personal data, nor even your phone number, so nobody knows whose smartphones are doing the measurements (except their owners). All we will receive from the application is the location of the smartphone when a particle hits it. And this can be registered only when the application is running, so you can decide, when you want to disclose your location.
- How can these groups of particles be detected?
We speak mostly about muons, the elementary particles that are energetic enough to travel through water, soil and other materials, but eventually are stopped. During their passage through matter the energy they carry is deposited in the surrounding medium. If they traverse a smart-phone photo-sensor, then a kind of an image is produced which with some expertise/algorithm can be interpreted as a particle hit. This is what we call a “catch”.
- What do you mean ‘catch’ – will this damage my phone?
There is no additional cosmic-ray energy deposited in our smart-phones just because we have an application that identifies cosmic-rays. The cosmic-ray flux is constantly invading our smart-phones, whether we analyze it or not. So no additional damage will be caused to your device when using our application.
- What is a “supermassive particle” and why are they good Dark Matter candidates?
What we mean by “supermassive” is the mass of 1020 eV or more. It’s about the mass of 10 millions of Higgs bosons – the heavy particles recently discovered at the Large Hadon Collider at CERN. Such “supermassive particles”, if they exist, do not have to be associated with visible astrophysical sources, they can travel freely through the space and we have no means to see them. However, if there is a lot of such particles, it might result in gravitational effects that can be detected.
- What do you mean by a “decay” – is it radioactive and dangerous?
In principle yes, the decay means that a particle transforms into multiple other particles. This process might be dangerous if you are heavily exposed to plenty of suych decays, like in the case of known radioactivity source. The good news is that the decay we consider can happen most likely far away from us, the products of the decay need to travel a lot until they reach the Earth atmosphere, and the atmosphere is our shield – it further reduces the energies of incoming “radioactivity”. That’s why we are not worried at all about cosmic rays on Earth, but we have to care when we plan a space mission.
- What is a “photon”?
“Photon” is the term used to describe the particle-behavior of light. This particle is massless and travels at the speed of light c (~10⁹ km/h). It is the carrier of the electromagnetic force and has a wide range of energies (from radiowaves to gamma-ray).
- What is an ‘eV’ and why not use watts – if the energy is that high why can’t we see them?
eV is a unit of energy that stands for “electron volt” and which correspnds to the amount of energy gained by a single electron moved across an electric potential difference of one volt. This can be of course converted to Joules, but this unit is too large for subatomic particles. The Joules and eV units can be compared to the light-years and meters used in astronomy and in everday life. On the other hand a 1020 eV particle is already as energetic as a well served tennis ball. As explained in question #11, atmospheric shielding prevents these particles of huge energy from reaching the ground. We can however detect their interactions with the amosphere.
- What is a ‘terrestrial accelerator’ and why can it help us?
Terrestrial accelerators, e.g. Large Hadron Collider in Switzerland, are man-made devices used to accelerate particles, collide them and look at the products of their interaction. The particle detectors that look at the effects of the collisions in terrestrial accelerators record also cosmic-ray signal, particularly useful if there is no artificial beam.
- How and what could effect these super-energetic photons on the way to the Earth?
What: other particles (Van Allen belts, IBEX ribbon), cosmic microwave radiation, unknown properties of the space-time, etc…
How: photons can interact with other particles. Moreover, space-time properties can affect the particle propagation (gravitational lensing, space-time holes, etc…)
- Particles “on their way to Earth” are traveling through space but you said they were “born in the Early Universe” so have they travelled in time?
Yes they have, or sort of. The speed of light has a finite value, so it takes a certain amount of time for photons or other particles to travel from one point to another. Photons born in the Early Universe have traveled for several billion years before reaching us. Observing these photons is like looking in the past. The Cosmic Microwave Background is one of the most famous examples of such concept.
- What do you mean by a ‘fundamental interaction’?
The “fundamental interactions” are those which happen between the physics actors (elementary particles) on the physics scene (space-time) on the most basic level. We know weak, strong, electromagnetic and gravitational interactions but we do not know what is their fundamental nature, e.g. do they have a common root? A popular direction of theoretical thinking is that this common root or origin manifests itself only at the very high energies, inaccessible on Earth. And CREDO addresses the highest energies known in the Universe.
- Why can’t observatories see super-preshowers – there’s lots of observatories and these things sound big and bright?
The existing large cosmic-ray observatories are designed to detect single air showers initiated by ultra-high energy particles. If a super-preshower is composed of relatively low energy particles, e.g. million times lower than primary energies typically observed by these observatories, and if these particles are too far apart from one another, then it becomes clear that they cannot be individually detected. CREDO wants to focus on ensembles of air showers, also those induced by particles with lower energies. Such showers are currently treated as background in big observatories.
- Why do I want to risk my smart phone detecting these things?
If just like us, you are interested in unraveling the mysteries of our Universe, you can be a part of it and explore the realm of the “unknown” with us. There is a very good potential for Nobel Prize.
- Where can I get the app from and does it cost anything?
There are existing applications (DECO, CRAYFIS) but they are not open to public yet. We need our own app and we need it open and free – for many reasons: get the development boosted, acquire new fresh ideas and configurations, increase credibility, attract more users, etc…
- How many other people are doing this?
The CREDO community is currently composed of about 50 people (students, researchers, engineers, etc…). We strongly count on making the project popular through the upcoming publications (science world) and through Zooniverse (citizen science project).
- Where does my data go and what is it used for?
A company operating the strongest supercomputer in Poland has recently been approached to discuss this project. It probably could and want to host all the CREDO computing activity. More details can be given if needed.
- a) Why you don’t create specific hardware for this project ?
CREDO rather defines a wide scientific program, it is not a single project. In this sense a specific hardware is possible to be designed only if a specific project is defined, with the expected characteristics of the hardware. There is a continuously ongoing work within the CREDO Collaboration to determine such characteristics for a number of scenarios. To give an example: one of the scenarios considered in a recent peer-reviewed article “for the CREDO Collaboration” (the preshower effect, //doi.org/10.1016/j.astropartphys.2020.102489), requires gamma telescopes, and there are many of them already taking data, and some others will be built soon – so this kind of infrastructure does not have to be reinvented in order to test this particular CREDO scenario.
We also try to invert the question: which scenarios can be tested with the available infrastructures, e.g. smartphones. Going in this direction we perform “bottom-up” studies that help to understand in detail the capacities of the available devices, e.g. the possibility of identification of muons using smartphone CMOS sensors is demonstrated in another peer-reviewed article “for CREDO”, Appl. Sci. 2021, 11(3), 1185; //doi.org/10.3390/app11031185, and it opens the door to testing the scenarios in which multi-primary cosmic ray events reach the Earth and produce air showers that contain muons.
b) And share schematic and software for all people who want connect
We share all the software on MIT license, please check our github repository, and if the Collaboration develops its own hardware the schematic will be shared as well – to facilitate participation/connection as much as possible, as required by our scientific objectives.
c) Like blitzortung ? I think this will be more stable for interpretation data from users
Excellent analogy – we also pursue global scale monitoring and research driven in some part by a large number of non-expert participants, and we want to be as open and as accessible as possible. You are welcome to join and help in this