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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>An Analysis of the State of Art of the Metaverse and Its Disruptive Impact on Services</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Andrea Cigliano</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Francesca Fallucchi</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Marco Gerardi</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Department of Engineering Science, Guglielmo Marconi University</institution>
          ,
          <addr-line>00193 Rome</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Leibniz Institute for Educational Media, Georg Eckert Institute</institution>
          ,
          <addr-line>38118 Brunswick</addr-line>
          ,
          <country country="DE">Germany</country>
        </aff>
      </contrib-group>
      <fpage>38</fpage>
      <lpage>46</lpage>
      <abstract>
        <p>The metaverse is a virtual environment where individuals may connect with one another, partake in a variety of activities, and access digital content. It coexists with the real world and it has the potential to significantly afect daily life as well as a variety of services and applications as it develops. To understand the importance of the impacts of the metaverse in today's society, just think of the disruptive technologies that enable it: Artificial Intelligence (AI), Extended Reality (ER), IoT, Digital Twin (DT) and Blockchain/NFT all with assistance with the availability of large, rich and structured/unstructured dataset and advanced computational models. Metaverse is cadidated (and not only) to redefine everyday life, designing activities and services/products provisioning towards increasing eficiencies, money saving and quality performance, with a big impact in everyone and helping the design and testing of next generation of internet. However, there still remain not only technical and interoperability issues but above all ethical, human, social, and cultural concerns as to the metaverse's influence upon its prospective scope in reconstructing the quality of urban life. This paper undertakes an upper-level scientific literature review of the area of the metaverse from a broader perspective. Further, it maps the some services and the relative requirements for declinate the enabling technologies of the metaverse, and explores their contributions.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Metaverse</kwd>
        <kwd>DT</kwd>
        <kwd>Digital Twin</kwd>
        <kwd>ER</kwd>
        <kwd>Extended Reality</kwd>
        <kwd>VR</kwd>
        <kwd>Virtual Reality</kwd>
        <kwd>Blockchain</kwd>
        <kwd>Nft</kwd>
        <kwd>Quantum Computing</kwd>
        <kwd>IOT</kwd>
        <kwd>LLM</kwd>
        <kwd>Large Language Model</kwd>
        <kwd>NLP</kwd>
        <kwd>Natural Language Model</kwd>
        <kwd>GenI</kwd>
        <kwd>Generative Artificial Intelligence</kwd>
        <kwd>DH</kwd>
        <kwd>Digital Humanity</kwd>
        <kwd>AI</kwd>
        <kwd>Artificial Intelligence</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>
        Recent investments and disinvestments by big tech and
some large companies in the metaverse have been seen as a
vital sign that the internet will transform and take on a new
dimension. After the Covid-19 pandemic, people have to
stay at home and perform many activities in digital
environments, which has accelerated the digitalization process. The
recent energy crisis has accelerated the process of
developing alternative energy sources or more sustainable
distribution and consumption [
        <xref ref-type="bibr" rid="ref1 ref2 ref3 ref4">1, 2, 3, 4</xref>
        ]. The new internet design
is planned to be developed to support a permanent digital
world where thousands and millions of people can act
simultaneously and switch between diferent platforms. However,
problems such as the management of energy resources and
equipment products that will support the necessary
infrastructure need to be overcome. In this context, this paper
intends to give is the state of the art of the development of
the metaverse, with particular regard to the technologies
used and the academic publications carried out in the
research areas related to Metaverse, Energy and Smart Cities.
As a first step is a brief conceptualization and definition of
the Metaverse. Basically it is a combination of the prefix
"meta" (meaning beyond) and the sufix "verso" (short for
Universe), if we wanted to define it, it is a composite world
with a coherent value system and an independent economic
system linked to the world physicist. The term metaverse
was first created by Neal Stephenson in his science fiction
novel Snow Crash in 1992. Herrman and Browning define it
as “a fully realized digital world that exists beyond the
analog one we live in” [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ]; Morgado explained it as "a plethora
of interconnected world" [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]. Meta Platforms, Inc. Bosworth
and Clegg (2021) describe it most simply: "The metaverse
is a set of virtual spaces where you can create and explore
with other people who are not in the same physical space
as you" [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ]. Putting the various definitions as a common
factor, metaverse means a collective, persistent and
interactive parallel reality created by synthesizing virtual worlds
in which people can use personal avatars to work, play and
communicate with each other [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ]. For this research we
conducted a literature search on a variety of online scientific
database sources and analyzed which services in real life
could be impacted by the metaverse is treated in the fields
of iot, energy, smart cities and other related collateral areas.
Every service has requirements in term of QOS (Quality Of
Services) [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ] . These requirements and relative QOS have
enabling technologies associated for the respect of its.
      </p>
      <sec id="sec-1-1">
        <title>1.1. Contributions</title>
        <p>We will describe metaverse current background, which helps
us explain why is a hot topic just now, despite having being
around for long time. We highlight current overview on
scientific pubblications on metaverse. We will further
highlight why, this time, the context is radically diferent from
what we experienced in the past: that is, why the upcoming
metaverse instances could represent something
semantically diferent from what we have seen in the technology
domain until now (an approximated answer: exponential
technology growth; unprecedented capabilities in data
generation, collection, and analysis; and, convergence of the
cyber-physical worlds). Based on the introduced
foundational material we develop our vision of the metaverse,
highlighting the metaverse-enabling technologies in particular
on developing energy and smart city services. Finally, in our
discussion we argument the thesis that the exposed threats
and the envisaged impacts generated by the development of
the metaverse call for an interdisciplinary approach where
computer science and engineering are critical.</p>
      </sec>
      <sec id="sec-1-2">
        <title>1.2. Sections</title>
        <p>The remainder of the paper is organized as follows. In
Section II we revise the method utilized and some background
information and related work in the field. In Section III,
we discuss the current istances on metaverse or more
correctly Metaverses, with a specific reference to the many
technologies correlated. In Section IV, based on the state
of play and the introduced guiding principles, we provide
our analysis of what are the most stringent criticalities of
the metaverse, also highlighting broad—in scope, depth, and
breadth—research directions in energy and smart city.
Finally, in Section V we provide our conclusions.</p>
      </sec>
    </sec>
    <sec id="sec-2">
      <title>2. Related Works</title>
      <p>
        The services impacted by the metaverse are analyzed and
treated in many real-world scenarios such as widely
distributed cloud sevices and solutions[
        <xref ref-type="bibr" rid="ref10 ref11">10, 11</xref>
        ], as well as
healthcare [
        <xref ref-type="bibr" rid="ref12 ref13 ref14">12, 13, 14</xref>
        ], gaming [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ], education [
        <xref ref-type="bibr" rid="ref16 ref17 ref18">16, 17, 18</xref>
        ],
culturalheritage [
        <xref ref-type="bibr" rid="ref19 ref20">19, 20</xref>
        ], smart city [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ], etc. Technologies involved
as metaverse enabler have been largely treated in these
domains of services and frameworks are proposed [
        <xref ref-type="bibr" rid="ref22 ref23">22, 23</xref>
        ]. In
these studies, AI [
        <xref ref-type="bibr" rid="ref24 ref25 ref26">24, 25, 26</xref>
        ] is one of main pillar to build
the metaverse. The other one is Digital Twin [
        <xref ref-type="bibr" rid="ref22 ref27">27, 22</xref>
        ], in
the metaverse every real single entity, concept, or operation
should be involved in the created 3D environment. Thus, a
huge amount of various types of data are highly needed in
such a system, including Internet of Things (IoT) collected
from various locations, devices and in an immersive while
being accessible through XR, including augumented reality
(AR), virtual reality (VR), and mixed reality (MR) [
        <xref ref-type="bibr" rid="ref22">22</xref>
        ]. The
technologies that allow human interaction with the
metaverse are mainly concentrated on case studies that look at
healthcare and gaming [
        <xref ref-type="bibr" rid="ref28 ref29 ref30 ref31 ref32">28, 29, 30, 31, 32</xref>
        ]. Metaverse
perspectives cannot be dissociated from a pervasive technology
like AI in fields like education and work [
        <xref ref-type="bibr" rid="ref16 ref24 ref33">16, 33, 24</xref>
        ]. The
research works on blockchain technology and the metaverse
is certainly the combination that has a high number of
research works on the use of cryptocurrencies and NFTs as
means of payment and beyond [
        <xref ref-type="bibr" rid="ref34 ref35 ref36 ref37 ref38 ref39 ref7">34, 7, 35, 36, 37, 38, 39</xref>
        ], also
including specific sectors, e.g. automotive [
        <xref ref-type="bibr" rid="ref40">40</xref>
        ].
      </p>
      <p>In this paper draws attention to metaverse state-of-art
and contributes to the answer to the research questions of
recurring research contexts on metaverse, namely:
• What is the Metaverse, and what are the supporting
technologies based on existing papers?
• How Metaverse has been detailed in research along
with other keywords?
• Are there constraints in the existing Metaverse
research which require further research?
The metaverse aims to be pervasive in everyone’s everyday
life, but there will be services that will be impacted more
than others that will lead to real disruption or "metaverse
service disruption" (MSD). Below are some services that will
undergo a profound transformation with the growth of the
metaverse .</p>
    </sec>
    <sec id="sec-3">
      <title>3. Metaverse service disruption</title>
      <p>Already nowadays the metaverse is used in many fields, but
the services that will be impacted in a disruption will be:
• Games and Virtual Reality: Players can immerse
themselves in 3D virtual worlds and interact with
other players in real time;
38–46
• Training and education: Professionals and students
can participate in training and education sessions
in virtual environments, similar to a physical
classroom;
• Conferences and Meetings: Businesses can host
virtual conferences and meetings in metaverse
environments, which ofer a more immersive experience
than a standard video conference;
• Shopping and entertainment: Consumers can
explore virtual stores, view and purchase products in
3D, and participate in entertainment events such as
concerts and shows;
• Arts and Culture: Visitors can explore virtual
museums and galleries, view 3D artwork, and interact
with other visitors.</p>
      <p>Below a list of Metaverse services and a typology of
classification:</p>
    </sec>
    <sec id="sec-4">
      <title>4. Metaverse services and implementation requirements</title>
      <p>In Table 3 it is reported the requirements of the Metaverse
typology.</p>
    </sec>
    <sec id="sec-5">
      <title>5. Metaverse architecture and</title>
    </sec>
    <sec id="sec-6">
      <title>Metaverse-enabling technologies and requirements coverage</title>
      <p>
        Since its first appearance, the concept of Metaverse is still
evolving with various descriptions, such as a second life
[
        <xref ref-type="bibr" rid="ref42">42</xref>
        ], 3D virtual worlds [
        <xref ref-type="bibr" rid="ref43">43</xref>
        ], and life-logging [
        <xref ref-type="bibr" rid="ref44">44</xref>
        ].
Commonly, the Metaverse is regarded as a fully immersive,
hyper spatiotemporal, and self-sustaining virtual shared space
blending the ternary physical, human, and digital worlds
[
        <xref ref-type="bibr" rid="ref45">45</xref>
        ]. Metaverse is recognized as an evolving paradigm of
the next-generation Internet and the evolution of Social
Media and the next mobile Internet revolutions [
        <xref ref-type="bibr" rid="ref45">45</xref>
        ], where
users can live as digital natives and experience an
alternative life in virtuality. The Metaverse integrates a variety
of enabling technologies [
        <xref ref-type="bibr" rid="ref34 ref47 ref48">47, 34, 48</xref>
        ], including the
NonTerrestrial Networks (NTNs) [
        <xref ref-type="bibr" rid="ref50">50</xref>
        ]. In particular, digital twin
produces a mirror image of the real world, Virtual Reality
(VR) and Augmented Reality (AR) provide immersive 3D
experience, 5G and beyond ofer ultra-high reliable and
ultralow latency connections for massive Metaverse devices
as wearable. It provides an immersive experience, generates
a mirror image of the real world based on Digital Twin
technology and Avatars, and builds an economic system based
on Blockchain technology. The Metaverse is comparable as
a new type of social form, that includes economic systems,
cultural systems, and legal systems, which are closely
related to reality, but have their own characteristics. Hyper
Spatiotemporality refers to the Metaverse, a virtual world
parallel to the real world. It breaks the boundaries of time
and space and ofers users an open, free and immersive
experience. The pervasiveness inherent in the Metaverse can
be seen in recent sci-fi movies/series such as Avatar(2009,
2022), Ready Player One (2018), The Peripheral (2022) and
others. The Metaverse is the tight integration, interaction,
and intertwining of the real and virtual worlds that requires
the integration of a variety of new technologies to create
a novel Internet application and social form. The method
Year
2022
2007
2013
2019
2021
2021
2021
2022
2021
2022
      </p>
      <p>
        Publication
Y. Wang et al. [
        <xref ref-type="bibr" rid="ref41">41</xref>
        ]
J. Sanchez [
        <xref ref-type="bibr" rid="ref42">42</xref>
        ]
J. D. N. Dionisio et al. [
        <xref ref-type="bibr" rid="ref43">43</xref>
        ]
A. Bruun et al. [
        <xref ref-type="bibr" rid="ref44">44</xref>
        ]
H. Ning et al. [
        <xref ref-type="bibr" rid="ref45">45</xref>
        ]
D. Grider et al. [
        <xref ref-type="bibr" rid="ref46">46</xref>
        ]
L.H. Lee et al. [
        <xref ref-type="bibr" rid="ref47">47</xref>
        ]
Q. Yang et al. [
        <xref ref-type="bibr" rid="ref34">34</xref>
        ]
H. Duan et al. [
        <xref ref-type="bibr" rid="ref48">48</xref>
        ]
S. Dhelim et al. [
        <xref ref-type="bibr" rid="ref49">49</xref>
        ]
      </p>
      <p>Metaverse related work detailed list
Brief description
A comprehensive survey of the fundamentals, security, and privacy of
metaverse. Specifically, an analysis on distributed metaverse architecture and its
key characteristics with ternary-world interactions.</p>
      <p>An Interactive Qualitative analysis of the user experience in Second Life, an
online Metaverse, in an undergraduate literature class. A focus group of
eighteen students produced a systems model including ten afinities with one
primary driver and one primary outcome.</p>
      <p>Moving from a set of independent virtual worlds to an integrated network
of 3D virtual worlds or Metaverse rests on progress in four areas: immersive
realism, ubiquity of access and identity, interoperability, and scalability.
Research in the wild has emerged in HCI as a way of studying participant
experiences in natural environments. Also, lifelogging tools such as
physiological sensors have become more feasible for gathering data continuously in
the wild.</p>
      <p>The development status of Metaverse, from the five perspectives of network
infrastructure, management technology, basic common technology, virtual
reality object connection, and virtual reality convergence, it introduces the
technical framework of Metaverse.</p>
      <p>The Metaverse is still emerging, but many key components have started to
take shape and are revolutionizing everything from e-commerce to media and
entertainment, and even real estate.</p>
      <p>The first efort to ofer a comprehensive framework that examines the latest
metaverse development under the dimensions of state-of-the-art technologies
and metaverse ecosystems, and illustrates the possibility of the digital ‘big
bang’.</p>
      <p>Dive into the metaverse by discussing how Blockchain and Artificial
Intelligence (AI) fuse with it through investigating the state-of-the-art studies
across the metaverse components.</p>
      <p>
        A three-layer metaverse architecture from a macro perspective, containing
infrastructure, interaction, and ecosystem.
a Fog-Edge hybrid computing architecture for Metaverse applications that
leverage an edge-enabled distributed computing paradigm.
used will be to analyze the papers and publications on the
Metaverse on the Smart Cities and Energy sector with a
focus on the technologies used in in particular by focusing
everything in the three layers in which the metaverse has
been defined in the scientific literature [
        <xref ref-type="bibr" rid="ref48">48</xref>
        ](see figure 1).
      </p>
      <p>To make it easier to understand the Metaverse concept
from a technological point of view, Figure 2 provides an
overview of what the metaverse enablign technologies
components.</p>
      <p>The Metaverse architecture does not separate the
physical world from the virtual world so that it can produce an
immersive experience. The infrastructure layer contains the
Reqs
basic requirements to support the operation of the virtual
world, such as computation, communication, blockchain,
and storage. The interaction layer is an essential part of
the interaction layer that bridges the physical and virtual
worlds. The ecosystem layer can provide a parallel living
environment with various services continuously serving all
the world’s inhabitants. A decentralized economic system
must also support the Metaverse ecosystem based on smart
contracts. Based on previous studies and literature, we
concluded that the most critical technologies to create a
Metaverse platform are Blockchain, Virtual/Augmented/Mixed
Reality (Extended Reality or XR), Artificial Intelligence,
Internet of Things (IoT), Digital Twin.</p>
      <sec id="sec-6-1">
        <title>5.1. Extended Reality</title>
        <p>
          Virtual Reality (VR) is a technology that uses software and
hardware to replace one’s perspective of the physical world
with a digitally created one [
          <xref ref-type="bibr" rid="ref51">51</xref>
          ]. The most popular VR
applications today employ comprehensive control of a user’s
senses (especially sight and hearing) to produce a completely
immersive experience that immerses the viewer in a
completely virtual environment that feels very realistic. AR is a
technology that combines the digital and physical worlds.
Object identification, plane detection, face recognition, and
movement monitoring are just a few of the technologies
it employs to distinguish real-world surfaces and objects.
Augmented reality could become our primary portal to the
Metaverse, as well as our primary interface to digital
resources, replacing the present ecology of phones and
desktops. Mixed reality is a fusion of augmented and virtual
reality that does not take place exclusively in the physical or
virtual environment [
          <xref ref-type="bibr" rid="ref52">52</xref>
          ]. Mixed reality can be employed in
a variety of applications to enrich the Metaverse, including
entertainment, military, healthcare, and robot operations
[
          <xref ref-type="bibr" rid="ref53 ref54 ref55 ref56">53, 54, 55, 56</xref>
          ]. Extended Reality (XR) is an umbrella term
that encompasses Augmented Reality (AR), Virtual Reality
(VR), Mixed Reality (MR), and everything in between.
        </p>
        <p>Within the rapidly-emerging Metaverse, the potential of
XR is driving expectations for a slew of previously
unimaginable possibilities. When Extended Reality replaces
conventional PCs and afects the way we work, play, and connect
on a daily basis, human lives will never be the same. People
will use the Metaverse’s virtual capabilities to apply for jobs,
earn a living, meet up with pals, shop, and even get married.</p>
      </sec>
      <sec id="sec-6-2">
        <title>5.2. Generative Artificial Intelligence (GenAI)</title>
        <p>
          The concept of the Metaverse refers to a collective virtual
shared space, created by the convergence of virtually
enhanced physical and digital reality. It is persistent and
provides enhanced immersive experiences. GenAI, particularly
Large Language Models (LLMs) and other generative
models, play a critical role in this environment by enabling the
creation of dynamic content and intelligent interactions.
GenAI refers to technologies that can generate new content
from existing data. This includes text, images, video, and
audio generation. LLMs, generative adversarial networks
(GANs), and variational autoencoders (VAEs) are pivotal
in crafting personalized and engaging content in the
metaverse. This study employs a mixed-methods approach,
integrating both qualitative and quantitative research. Data is
collected through virtual ethnography in various Metaverse
platforms, interviews with developers and users, and
analysis of user-generated content within these environments.
The study also reviews existing literature on generative AI
applications and their implications for virtual worlds. GenAI
and in general AI is a research discipline proceeded based
on the hypothesis that every aspect of learning can in
principle be so precisely described [
          <xref ref-type="bibr" rid="ref57">57</xref>
          ]. The state-of-the-art AI
studies focus on machine learning, deep learning, and
reinforcement learning in the fields including computer vision,
decision-making, and natural language process (NLP).
Intuitively, the breakthroughs of AI in the real world motivate
people to realize Metaverse. For example, machine learning
provides technical support for all systems in Metaverse to
reach or exceed the level of human’s learning. It shall
significantly afect the operational eficiency and the intelligence
of Metaverse. Intelligent voice services provide technical
support, such as voice recognition and communication, for
Metaverse users.
5.2.1. Applications of Generative AI in the Metaverse
• Content creation in a Dynamic Environment
Design): Generative AI algorithms can create
expansive, detailed virtual environments on-the-fly,
adapting to user interactions;
• Content creation with Character and Avatar
Customization: AI-driven tools enable users to create
highly personalized avatars and non-player
characters (NPCs) that can interact intelligently with users;
• Interaction and Engagement with Natural
Language Processing (NLP): AI-enhanced
communication tools allow for real-time language translation
and generation of realistic dialogues with NPCs;
• Behavioral AI with enhances the responsiveness of
environments and characters to user actions,
creating a more immersive experience;
• Accessibility and Inclusivity with Adaptive
Interfaces: AI algorithms can adjust the user interface
dynamically to accommodate users’ physical and
cognitive needs.
        </p>
      </sec>
      <sec id="sec-6-3">
        <title>5.3. Internet of Things (IoT)</title>
        <p>
          The Metaverse gathers data from a variety of Internet of
Things (IoT) devices to ensure that it runs eficiently in
several applications of the Metaverse such as medicine,
education and Smart Cities. The IoT devices will connect the
Metaverse through the use of a diverse range of hardware,
controllers, and physical items. Connecting to the
Metaverse and navigating both physically and virtually is made
possible by IoT devices equipped with specialized sensors.
The capacity of IoT devices to perform operations in the
Metaverse will be critical to the user’s ability to operate in
the Metaverse. Whether remotely performing large-scale
computing tasks, accessing large databases, or providing
shared experiences between users, they are inextricably
linked to networks and communications. The fifth
generation (5G) and the sixth generation (6G) are the
communication foundation of the Metaverse. 5G has the advantages of
high speed, low delay, ubiquitous network, low power
consumption and interconnection of all things, which makes it
possible to realize the Metaverse. 6G will break the
limitations of time and virtual reality, expand the service objects
from humans, machines, and things in the physical world to
the “environment” of the virtual world, and realize the
cooperation between humans-machines-things-environment by
connecting the physical world and the virtual world,
providing the network foundation for the Metaverse. In the 5G and
6G network environment, quantum communication ensures
the communication security in the Metaverse. Post quantum
cryptography is already a reality today, quantum
communication provides high security by applying quantum key
based on quantum no-cloning theorem and uncertainty
principle [
          <xref ref-type="bibr" rid="ref43">43</xref>
          ]. Moreover, quantum communication improves
the overall security due to the superposition properties of
qubits.
        </p>
      </sec>
      <sec id="sec-6-4">
        <title>5.4. Digital Twin</title>
        <p>
          Digital Twin is a digital reproduction of a real product or
component created by the combination of simulations and
service metadata [
          <xref ref-type="bibr" rid="ref58">58</xref>
          ]. Data from numerous sources are
included in the digital representation throughout the product
life cycle. These data are constantly restructured and shown
in a variety of ways in order to forecast current and future
situations in both operational and design settings, therefore
improving decision making [
          <xref ref-type="bibr" rid="ref59">59</xref>
          ]. Constructing a complex
virtual model that is the counterpart or twin of a physical
object in the real world is what Digital Twin is all about.
It employs simulation, machine learning, and reasoning to
aid decision-making and is generated from real-time data.
Metaverse will be able to ofer remote maintenance
workshops for machines that need to be repaired, which might be
linked to or mapped onto a real workshop, thanks to digital
twin and simulation technologies. Digital twins are an
important part of the Metaverse because of their non-artistic
qualities.
        </p>
      </sec>
      <sec id="sec-6-5">
        <title>5.5. Blockchain</title>
        <p>Metaverse envisaged scenario that it is closely related is
just a parallel world, where the economic ecology is
inevitable. The digital assets are the core functions provided
by the blockchain, such as the homogenized tokens based
on ERC-20 and the non-homogenized tokens based on
ERC721 or ERC-1155. Since the blockchain technology maintain
the smooth economic operation of Metaverse, blockchain
technology is the soul of the Metaverse. The motivation
behind integration of blockchain in the metaverse can be
summarized in:
• Ensuring Data Privacy and Security
• Ensuring the Quality of the Data
• Enabling Seamless and Secured Data Sharing
• Enabling Data Interoperability
• Ensuring Data Integrity</p>
        <p>
          There are many use cases of application of blockchain in
the metaverse, for example:
• Financial system: Tamper-proof, openness,
transparency and decentralization are the four significant
features in blockchain. In the Metaverse, millions of
transactions happen for goods exchange in a short
time, so the security and eficiency of these
transactions must be guaranteed. Based on the
abovementioned features, blockchain is a good candidate
for the large-scale and scalable economic system
construction in the virtual world
• Smart contract deployment: The inherent nature of
the blockchain network allows smart contracts to be
automated, programmable, open, transparent and
verifiable among other remarkable features, thus
allowing for onchain trusted interactions without the
need for a thirdparty verification platform. If the
ifnancial system in the Metaverse is built on top of
the blockchain, the characteristics of smart contracts
can be used to decentralise the operation of contracts
in a programmed, noncustodial, verifiable, traceable
and trustworthy manner, thus significantly reducing
the harmful behaviours such as rent-seeking,
corruption and underhanded operations that may exist
in the financial system, and can be widely used in
the financial, social and gaming sectors.
• NFTs: The most important feature of NFT is
indivision and uniqueness, which make it suitable for
identity representation, for example, assets that are
exclusive and indivisible and can be freely traded
and transferred. In the Metaverse, these virtual
assets come with certificates called NFTs that indicate
ownership.
• Cryptocurrency: is one of the main applications
under the spotlight empowered by blockchain. It
also makes blockchain more popular. The trust of
a wide range of users supports the value system
of cryptocurrencies and drives both the circulation
and trading of cryptocurrencies. To date, more than
12.000 virtual currencies have been issued
worldwide, and new virtual currencies are still being
created every single day. Like the real world builds
upon fiat currencies, the Metaverse inevitably needs
cryptocurrencies, which deliver value during their
circulation, payment, and currency of settlement.
In detail, blockchain systems have implemented a
series of operations for cryptocurrencies, such as
creation, recording, and trading. Traditionally,
Bitcoin [
          <xref ref-type="bibr" rid="ref35">35</xref>
          ] adopts the UTXO (Unspent Transaction
Outputs) transaction model to trace the usages of
this cryptocurrency, while Ethereum [
          <xref ref-type="bibr" rid="ref36">36</xref>
          ] records
the balance of each account address, which can be
queried directly through the Ethereum dataset tools
(e.g. Etherscan). Both UTXO and Ethereum adopt
the Proof of Work (PoW) consensus. Miners mint
coins by generating new blocks. However, there is
a cost for them to generate blocks. In such PoW
consensus, miners mine blocks by calculating a hash
puzzle, which consumes a giant amount of
electricity. For Ethereum 2.0, miners under the PoS (Proof of
Stake) consensus mechanism mine blocks by
electing, which depends on the coin age of miners [
          <xref ref-type="bibr" rid="ref37">37</xref>
          ].
Using blockchain technologies, there are multiple
ways to deal with cryptocurrency exchanges. The
vast majority of cryptocurrency exchanges occur in
centralized exchanges such as OKEx and AOFEX.
The advantages of the centralized exchanges include
low-latency transactions, simple interfaces and a
certain level of security. However, the centralized
exchanges also experience scandals such as price
manipulation by insiders taking advantage of
information asymmetries. Other cryptocurrency exchanges
occur in decentralized exchanges, where smart
contracts or other peer-to-peer network execute
transactions automatically [
          <xref ref-type="bibr" rid="ref38">38</xref>
          ]. In some cases, the smart
contracts, e.g., IDex and Paradex, maintain
continuouslimited order books ofchain, a counterparty
of the order or the exchange itself performs order
matching and submits order pairs to the smart
contract for processing. In other cases, such as Uniswap
and Bancor, the smart contract performs as a
counterparty and trade with its user directly. It is easy
to foresee that metaverse built by diferent
corporations will coexist in the near future. Thus, various
cryptocurrencies used in those smaller metaverses
need to be exchanged like fiat currencies in the
physical world. We envision that multiple
cryptocurrencies will also coexist in future Metaverse. The
Metaverse users will naturally need to exchange diferent
cryptocurrencies.
        </p>
      </sec>
    </sec>
    <sec id="sec-7">
      <title>6. Results and discussion</title>
      <p>
        The Metaverse, designed as a simulation of the natural world,
covers all areas related to humans and society and ofers a
suitable working platform for researchers in all fields, from
health to sports, from education to art. This the research
deals with the scientific aspect of the Metaverse studies and
examines academic studies in Energy and Smart Cities and
in other research keywords connected from a technological
and related domain point of view. Most of the studies in
the literature have explained the concept of the Metaverse.
The implemented applications observed, are mainly at the
prototype level. However, these studies, which make
significant contributions to the literature in terms of design and
editing, have a high potential to be realized when suficient
technical infrastructure is provided. The AR/VR
technologies, digital twins, and Blockchain applications, which are
components of the Metaverse, have been actively used for a
while. Furthermore, technological developments that allow
the purchase and sale of non-Fungible Token (NFT)-based
artworks, souvenirs, and lands, which have been very
popular lately, show that the promised universe is one step
closer. However, for this fictional universe to be fully
realized, 5G technology needs to come into play, AR/VR
hardware and content should become widespread, and the use
of peer2peer technologies should increase. When the
Metaverse is brought to life as it was designed, it will be possible
to perform many daily activities such as working,
traveling, shopping, going to school, having fun by creating a 3d
avatar in a digital universe. Any change users make in the
Metaverse will be permanently visible to almost everyone,
thus providing users with greater identity and continuity
of experience. The Metaverse becoming a reality will
support and transform existing research topics and reveal new
research areas. In addition, this digital universe will be a
big data source with the data it will produce. Therefore, it
will also provide a suitable working platform for big data,
data science, and artificial intelligence researchers. With
the development of the technological infrastructure and the
interest of researchers in this field, it is expected that the
number of scientific studies in the area will increase, and
richer content will emerge soon. All these developments
herald an exciting future. An open Metaverse, this is one
of the challenging issues that will determine, in my view,
its success or not. In this context, the key word is
interoperability. Not only does the so-called Metaverse still not
exist in the forms in which the marketing of certain
companies wants to sell it. But not even a single Metaverse
is the digital twin of the physical world. Rather, there are
several platforms on the market, each with its own rules
of engagement and its specificities. Meta itself has realized
that isolation is not convenient. In his latest presentation to
the market, Zuckerberg insisted not only on the legs of the
Horizon avatars, but also on collaborations with other
companies, such as Microsoft, Adobe and Zoom. A sign that if
the Facebook founder really wants to make the project with
which he hopes to inject new life into a company aflicted
by the decline in advertising revenues, by the compromised
public image and by a social competition that he cannot
keep up with, it is time to come to terms [
        <xref ref-type="bibr" rid="ref49">49</xref>
        ]. Diferent
from the physical world, the digital creation in the virtual
world might be unlimited. The identity of digital objects
determines value instead of the undiferentiated labor in the
conventional economy. In the field of digital creation, it is
necessary to develop authoring tools to enable the users to
produce original content easily and gain rewards eficiently
at a low cost. Those tools could improve the enthusiasm
of content producers of the Metaverse. The marginal
benefits will increase in the Metaverse instead of diminishing
marginal benefits of production in the physical world. The
diference in marginal benefits between the physical world
and the virtual world demands a value conversion
mechanism to bridge their gap. In future Metaverse, people prefer
to turn to their virtual cabinet to select a digital outfit, while
companies begin to hype the virtual skins, virtual clothing,
and even virtual estates with a high price which will block a
large portion of players to join in the Metaverse. Hence, it is
necessary to propose particular governance mechanisms
under the cooperation of worldwide companies. Furthermore,
how to establish a digital currency system that enables the
38–46
currency exchange between the Metaverse and the physical
world remains an open issue. In addition, the transaction
volume and frequency that occurred in the Metaverse will
become extremely much higher than happened in the
physical world. Thus, how to support such high-volume and
high-frequency transactions remains a challenging problem
in the future Metaverse. Another issue related to future
Metaverse might be the inflation caused by massive
cryptocurrency supplements in a decentralized economy system
built upon blockchain and AI technologies.
      </p>
    </sec>
    <sec id="sec-8">
      <title>7. Conclusions</title>
      <p>The analysis carried out on the research publications
using a sample of the universe searched through the online
metadata sites of the research works for certain keywords,
it emerged that the metaverse it is already having an impact
on certain categories of services and will be increasingly
disruptive. The services involved will be increasingly pervasive
as the technologies enabling the metaverse are pervasive.
The research area relating to the metaverse and quantum
computing deserves a separate discussion, which deserves
a separate discussion as the latter is a rapidly growing and
maturing technological area. The challenges facing us in
the metaverse are enormous in the short to medium term.
According to the current trend, it seems that metaverse will
be the future from multiple perspectives and ofers limitless
possibilities from many frontiers. Enabling technologies
such as Blockchain, GenAI, XR, Digital Twin will be
instrumental in realizing the true potential of the Metaverse.
There is a huge research prospect in these areas.
38–46</p>
    </sec>
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