Exciting discoveries have come from an international drilling project, the Deep Sea Drilling Project. Since 1968, a drill ship, the Glomar Challenger, has drilled nearly a thousand holes into the deep ocean basins, taking samples of deep-sea sediment and crust. One early discovery suggests that the Mediterranean dried up completely between 5 and 12 million years ago, leaving thick beds of sun-baked salts as evidence buried in today’s ocean floor.
From the late 1930s, new techniques have opened up in submarine geology. Gravity measurements and geotectonic imagery have allowed accurate mapping of the sea surface and the bottom structure of the oceans. The ocean floor, far from being smooth and flat, is marked by huge mountain ranges – the mid-ocean ridge that form part of a global network which extends for more than 80,000 km. In places such as Iceland, Ascension and the Galapagos Islands, the ridges rise above sea level.
The ocean floor is also cut by deep trenches which mark subduction zones and are punctuated by isolated seamounts. Because a mid-ocean ridge is submerged at very deep depths in the ocean, its existence was not even known until the 1950s, when it was discovered by Vema, a ship of the Lamont-Doherty Geological Observatory of Columbia University, that traversed the Atlantic Ocean and recorded data about the ocean floor from the ocean surface.
The mountain range was named the Mid-Atlantic Ridge. At first, it was thought to be a phenomenon specific to the Atlantic Ocean, because nothing like such a massively-long undersea mountain chain had ever been discovered before. However, as surveys of the ocean floor continued to be conducted around the world, it was discovered that every ocean contained parts of the mid-ocean ridge.
The discovery of what mid-ocean ridge systems represented, the sites of crust formation, or constructive plate margins, was a major breakthrough in earth sciences. Basaltic volcanism, upwelling of magma consisting mainly of basalt characterises ocean ridge.
Convective movements within the mantle force the overlying lithosphere move apart, allowing hot magma to reach the sea floor. At ridge crests, a zone of rifting separates regions of sea floor which are moving apart at 2-15 centimetres per year.
Because the oceanic crust cannot withstand sufficient stress to allow for variations in spreading rate and changes in convection pattern, ocean ridge consist of straight sections offset by transform faults, along which different sections of a plate slide past each other. This phenomenon is known to be caused by convection currents in the plastic, very weak upper mantle, or asthenosphere.
One of the key pieces of information came from paleomagnetic studies along the Mid-Atlantic Ridge. It was found that only half the rocks on each side of the ridge-axis near Iceland showed normal magnetic polarity; the remainder had a reversed polarity.
The pattern of normal and reversed polarity was manifested in a magnetic striping of the oceanic crust, mirrored on each side of the ridge crest. The alternating pattern of normal and reversed polarity rocks is produced as successive belts of lava are extruded at the site of a divergent plate margin. At the mid-ocean ridge and associated rift zones, the new sea floor is generated then carried away from the ridge-axis by lateral mantle motions.
When individual stripes were dated, it was found that the rocks became older with increasing distance from the crest. In other words, the sea floor was spreading apart. Such spreading characterises all ocean ridge where lithospheric plate divergence occurs. During the past 80 million years, the Atlantic has spread at a rate of 2 centimetres per year. About 4 cubic km of new crust is produced at mid-ocean ridge every year.
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Darknet
Definition:
Darknet, also known as dark web or darknet market, refers to the part of the internet that is not indexed or accessible through traditional search engines. It is a network of private and encrypted websites that cannot be accessed through regular web browsers and requires special software and configuration to access.
The darknet is often associated with illegal activities such as drug trafficking, weapon sales, and hacking services, although not all sites on the darknet are illegal.
Examples:
Examples of darknet markets include Silk Road, AlphaBay, and Dream Market, which were all shut down by law enforcement agencies in recent years.
These marketplaces operate similarly to e-commerce websites, with vendors selling various illegal goods and services, such as drugs, counterfeit documents, and hacking tools, and buyers paying with cryptocurrency for their purchases.
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Artificial Intelligence
Definition:
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- Anonymity: Darknet allows users to communicate and transact with each other anonymously. Users can maintain their privacy and avoid being tracked by law enforcement agencies or other entities.
- Access to Information: The darknet provides access to information and resources that may be otherwise unavailable or censored on the regular internet. This can include political or sensitive information that is not allowed to be disseminated through other channels.
- Freedom of Speech: The darknet can be a platform for free speech, as users are able to express their opinions and ideas without fear of censorship or retribution.
- Secure Communication: Darknet sites are encrypted, which means that communication between users is secure and cannot be intercepted by third parties.
- Illegal Activities: Many darknet sites are associated with illegal activities, such as drug trafficking, weapon sales, and hacking services. Such activities can attract criminals and expose users to serious legal risks.
- Scams: The darknet is a hotbed for scams, with many fake vendors and websites that aim to steal users’ personal information and cryptocurrency. The lack of regulation and oversight on the darknet means that users must be cautious when conducting transactions.
- Security Risks: The use of the darknet can expose users to malware and other security risks, as many sites are not properly secured or monitored. Users may also be vulnerable to hacking or phishing attacks.
- Stigma: The association of the darknet with illegal activities has created a stigma that may deter some users from using it for legitimate purposes.
- Virtual assistants: Siri, Alexa, and Google Assistant are examples of virtual assistants that use natural language processing to understand and respond to users’ queries.
- Recommendation systems: Companies like Netflix and Amazon use AI to recommend movies and products to their users based on their browsing and purchase history.
- Efficiency: AI systems can work continuously without getting tired or making errors, which can save time and resources.
- Personalization: AI can help provide personalized recommendations and experiences for users.
- Automation: AI can automate repetitive and tedious tasks, freeing up time for humans to focus on more complex tasks.
- Job loss: AI has the potential to automate jobs previously performed by humans, leading to job loss and economic disruption.
- Bias: AI systems can be biased due to the data they are trained on, leading to unfair or discriminatory outcomes.
- Safety and privacy concerns: AI systems can pose safety risks if they malfunction or are used maliciously, and can also raise privacy concerns if they collect and use personal data without consent.
Darknet
Definition:
Darknet, also known as dark web or darknet market, refers to the part of the internet that is not indexed or accessible through traditional search engines. It is a network of private and encrypted websites that cannot be accessed through regular web browsers and requires special software and configuration to access.
The darknet is often associated with illegal activities such as drug trafficking, weapon sales, and hacking services, although not all sites on the darknet are illegal.
Examples:
Examples of darknet markets include Silk Road, AlphaBay, and Dream Market, which were all shut down by law enforcement agencies in recent years.
These marketplaces operate similarly to e-commerce websites, with vendors selling various illegal goods and services, such as drugs, counterfeit documents, and hacking tools, and buyers paying with cryptocurrency for their purchases.
Pros :
Cons:
Artificial Intelligence
Definition:
AI, or artificial intelligence, refers to the development of computer systems that can perform tasks that would normally require human intelligence, such as recognizing speech, making decisions, and understanding natural language.
Examples:
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