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It's really easy to see the data and make decisions from it without having to be an expert. Flash drives may present a significant security challenge for some organizations. In other projects Wikimedia Commons. As of mid [update] , [ needs update ] this was an expensive alternative to standard password protection offered on many new USB flash storage devices. Like all flash memory devices, flash drives can sustain only a limited number of write and erase cycles before the drive fails. The availability of inexpensive flash drives has enabled them to be used for promotional and marketing purposes, particularly within technical and computer-industry circles e.

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The metric of this form has significant difficulties because all known warp-drive spacetime theories violate various energy conditions. If certain quantum inequalities conjectured by Ford and Roman hold, [19] the energy requirements for some warp drives may be unfeasibly large as well as negative.

Counterarguments to these apparent problems have also been offered. Chris Van den Broeck of the Katholieke Universiteit Leuven in Belgium, in , tried to address the potential issues. Later, by slightly modifying the Van den Broeck metric, Serguei Krasnikov reduced the necessary total amount of negative mass to a few milligrams. However, Van den Broeck concludes that the energy densities required are still unachievable, as are the small size a few orders of magnitude above the Planck scale of the spacetime structures needed.

Krasnikov proposed that if tachyonic matter cannot be found or used, then a solution might be to arrange for masses along the path of the vessel to be set in motion in such a way that the required field was produced.

But in this case, the Alcubierre drive vessel can only travel routes that, like a railroad, have first been equipped with the necessary infrastructure.

The pilot inside the bubble is causally disconnected with its walls and cannot carry out any action outside the bubble: For example, travelling to Vega which is 25 light-years from Earth requires arranging everything so that the bubble moving toward Vega with a superluminal velocity would appear; such arrangements will always take more than 25 years.

Coule has argued that schemes, such as the one proposed by Alcubierre, are infeasible because matter placed en route of the intended path of a craft must be placed at superluminal speed—that constructing an Alcubierre drive requires an Alcubierre drive even if the metric that allows it is physically meaningful. Coule further argues that an analogous objection will apply to any proposed method of constructing an Alcubierre drive.

Brendan McMonigal, Geraint F. Lewis , and Philip O'Byrne have argued that when an Alcubierre-driven ship decelerates from superluminal speed, the particles that its bubble has gathered in transit would be released in energetic outbursts akin to a sonic boom shockwave ; in the case of forward-facing particles, energetic enough to destroy anything at the destination directly in front of the ship.

The amount of negative energy required for such a propulsion is not yet known. Similar constraints apply to Krasnikov's superluminal subway. Calculations by physicist Allen Everett show that warp bubbles could be used to create closed timelike curves in general relativity, meaning that the theory predicts that they could be used for backwards time travel.

Some results in semiclassical gravity appear to support the conjecture, including a calculation dealing specifically with quantum effects in warp-drive spacetimes that suggested that warp bubbles would be semiclassically unstable, [10] [29] but ultimately the conjecture can only be decided by a full theory of quantum gravity.

Miguel Alcubierre briefly discusses some of these issues in a series of lecture slides posted online, [31] where he writes: In the next slide he brings up the chronology protection conjecture and writes: The conjecture does not prohibit faster-than-light travel. It just states that if a method to travel faster than light exists, and one tries to use it to build a time machine, something will go wrong: In , a NASA laboratory announced that they had constructed an interferometer that they claim will detect the spatial distortions produced by the expanding and contracting spacetime of the Alcubierre metric.

The Star Trek television series used the term " warp drive " to describe their method of faster-than-light travel. Neither the Alcubierre theory, nor anything similar, existed when the series was conceived, but Alcubierre stated in an email to William Shatner that his theory was directly inspired by the term used in the show [34] and references the "'warp drive' of science fiction" in his article.

From Wikipedia, the free encyclopedia. Warp-field experiments and White—Juday warp-field interferometer. Classical and Quantum Gravity. Archived PDF from the original on 23 February Cramer, where Cramer notes that "Alcubierre, following the lead of wormhole theorists, argues that quantum field theory permits the existence of regions of negative energy density under special circumstances, and cites the Casimir effect as an example.

Archived PDF from the original on 29 March Retrieved 1 October Harold "Sonny" White 30 September Archived PDF from the original on 20 October The most common use of flash drives is to transport and store personal files, such as documents, pictures and videos. Individuals also store medical information on flash drives for emergencies and disaster preparation.

With wide deployment s of flash drives being used in various environments secured or otherwise , the issue of data and information security remains important. The use of biometrics and encryption is becoming the norm with the need for increased security for data; on-the-fly encryption systems are particularly useful in this regard, as they can transparently encrypt large amounts of data.

In some cases a secure USB drive may use a hardware-based encryption mechanism that uses a hardware module instead of software for strongly encrypting data. COFEE is a set of applications designed to search for and extract digital evidence on computers confiscated from suspects. Usually, new firmware image is downloaded and placed onto a FAT16 - or FAT32 -formatted USB flash drive connected to a system which is to be updated, and path to the new firmware image is selected within the update component of system's firmware.

Also, HP has introduced a USB floppy drive key , which is an ordinary USB flash drive with additional possilibility for performing floppy drive emulation, allowing its usage for updating system firmware where direct usage of USB flash drives is not supported.

Desired mode of operation either regular USB mass storage device or of floppy drive emulation is made selectable by a sliding switch on the device's housing. Most current PC firmware permits booting from a USB drive, allowing the launch of an operating system from a bootable flash drive. Such a configuration is known as a Live USB. Original flash memory designs had very limited estimated lifetimes. The failure mechanism for flash memory cells is analogous to a metal fatigue mode; the device fails by refusing to write new data to specific cells that have been subject to many read-write cycles over the device's lifetime.

Originally, this potential failure mode limited the use of "live USB" system to special-purpose applications or temporary tasks, such as:. As of [update] , newer flash memory designs have much higher estimated lifetimes.

Several manufacturers are now offering warranties of 5 years or more. Such warranties should make the device more attractive for more applications. By reducing the probability of the device's premature failure, flash memory devices can now be considered for use where a magnetic disk would normally have been required. Flash drives have also experienced an exponential growth in their storage capacity over time following the Moore's Law growth curve.

Storage capacities in this range have traditionally been considered to offer adequate space, because they allow enough space for both the operating system software and some free space for the user's data. In particular, Mac OS X However, for installation of Windows 7 and later versions, using USB flash drive with hard disk drive emulation as detected in PC's firmware is recommended in order to boot from it.

Transcend is the only manufacturer of USB flash drives containing such feature. Flash drives are used to carry applications that run on the host computer without requiring installation.

While any standalone application can in principle be used this way, many programs store data, configuration information, etc.

The U3 company works with drive makers parent company SanDisk as well as others to deliver custom versions of applications designed for Microsoft Windows from a special flash drive; U3-compatible devices are designed to autoload a menu when plugged into a computer running Windows. Applications must be modified for the U3 platform not to leave any data on the host machine. U3 also provides a software framework for independent software vendors interested in their platform.

Ceedo is an alternative product, with the key difference that it does not require Windows applications to be modified in order for them to be carried and run on the drive. Similarly, other application virtualization solutions and portable application creators , such as VMware ThinApp for Windows or RUNZ for Linux can be used to run software from a flash drive without installation.

In October , Apple Inc. A wide range of portable applications which are all free of charge, and able to run off a computer running Windows without storing anything on the host computer's drives or registry, can be found in the list of portable software. Some value-added resellers are now using a flash drive as part of small-business turnkey solutions e. The drive is used as a backup medium: Alternatively, the drive can be left inserted through the business day, and data regularly updated.

In either case, the drive is removed at night and taken offsite. Flash drives also have disadvantages. They are easy to lose and facilitate unauthorized backups.

A lesser setback for flash drives is that they have only one tenth the capacity of hard drives manufactured around their time of distribution. Many companies make small solid-state digital audio players , essentially producing flash drives with sound output and a simple user interface. Some of these players are true USB flash drives as well as music players; others do not support general-purpose data storage. Other applications requiring storage, such as digital voice or sound recording , can also be combined with flash drive functionality.

Many of the smallest players are powered by a permanently fitted rechargeable battery, charged from the USB interface. Fancier devices that function as a digital audio player have a USB host port type A female typically. Digital audio files can be transported from one computer to another like any other file, and played on a compatible media player with caveats for DRM -locked files.

This allows a USB flash drive containing media files in a variety of formats to be played directly on devices which support the format. In addition to five high- bitrate MP3s , it also included a video, pictures, lyrics, and guitar tablature. Rave , a compilation album released by the Kiss Network in April The availability of inexpensive flash drives has enabled them to be used for promotional and marketing purposes, particularly within technical and computer-industry circles e.

They may be given away for free, sold at less than wholesale price, or included as a bonus with another purchased product. Usually, such drives will be custom-stamped with a company's logo , as a form of advertising. The drive may be blank, or preloaded with graphics, documentation, web links, Flash animation or other multimedia , and free or demonstration software.

Some preloaded drives are read-only, while others are configured with both read-only and user-writable segments. Such dual-partition drives are more expensive. Flash drives can be set up to automatically launch stored presentations, websites, articles, and any other software immediately on insertion of the drive using the Microsoft Windows AutoRun feature.

In the arcade game In the Groove and more commonly In The Groove 2 , flash drives are used to transfer high scores, screenshots , dance edits, and combos throughout sessions.

As of software revision 21 R21 , players can also store custom songs and play them on any machine on which this feature is enabled. While use of flash drives is common, the drive must be Linux compatible. However, any USB flash drive can be used in this arcade game. Flash drives use little power, have no fragile moving parts, and for most capacities are small and light. Data stored on flash drives is impervious to mechanical shock, magnetic fields, scratches and dust.

These properties make them suitable for transporting data from place to place and keeping the data readily at hand. Flash drives also store data densely compared to many removable media. Flash drives implement the USB mass storage device class so that most modern operating systems can read and write to them without installing device drivers.

The flash drives present a simple block-structured logical unit to the host operating system, hiding the individual complex implementation details of the various underlying flash memory devices.

The operating system can use any file system or block addressing scheme. Some computers can boot up from flash drives. Specially manufactured flash drives are available that have a tough rubber or metal casing designed to be waterproof and virtually "unbreakable". These flash drives retain their memory after being submerged in water, and even through a machine wash.

Leaving such a flash drive out to dry completely before allowing current to run through it has been known to result in a working drive with no future problems. Channel Five 's Gadget Show cooked one of these flash drives with propane, froze it with dry ice , submerged it in various acidic liquids, ran over it with a jeep and fired it against a wall with a mortar.

A company specializing in recovering lost data from computer drives managed to recover all the data on the drive. The applications of current data tape cartridges hardly overlap those of flash drives: Media have a very high capacity and very fast transfer speeds, but store data sequentially and are very slow for random access of data. While disk-based backup is now the primary medium of choice for most companies, tape backup is still popular for taking data off-site for worst-case scenarios and for very large volumes more than a few hundreds of TB.

Floppy disk drives are rarely fitted to modern computers and are obsolete for normal purposes, although internal and external drives can be fitted if required. Floppy disks may be the method of choice for transferring data to and from very old computers without USB or booting from floppy disks, and so they are sometimes used to change the firmware on, for example, BIOS chips.

Devices with removable storage like older Yamaha music keyboards are also dependent on floppy disks, which require computers to process them. Newer devices are built with USB flash drive support. The various writable and rewritable forms of CD and DVD are portable storage media supported by the vast majority of computers as of A lifetime of photos on all your devices. Without worrying about space on your devices. All in one place.

All your files available from all your devices. Organize files however you want. Get to them on any device you want. Good for safely storing all the basics, like contacts, calendars, and notes. Lots of Photos GB.

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