Saya betul-betul merinding ketika membaca daftar ini (di sumbernya dalam bahasa Inggris), karena saya telah mengetahui bahwa… ternyata ada gravitasi di luar angkasa! (loh?) Karena itu, saya ingin berbagi daftar ini dengan Anda.
Tidak ada yang lebih bagus dibanding memecahkan mitos (mythbusting; yang membuat sebuah program Discovery Channel, Mythbusters, terkenal), jadi inilah dia daftar kesalahpahaman dan mitos yang diketahui orang-orang tapi bisa dibilang konyol – kali ini tentang ilmu pengetahuan.10. Perubahan karena Evolusi
Mitos: Evolusi mengakibatkan sesuatu beranjak dari “rendah” ke “tinggi”
Padahal faktanya adalah bahwa seleksi alam mengeluarkan gen yang tidak sehat dari kolam gen, ada banyak kasus ketika sebuah organisme tak sempurna selamat. Contohnya adalah jamur, hiu, udang, dan lumut – semuanya tetap sama sepanjang waktu. Organisme-organisme ini beradaptasi dengan lingkungan mereka tanpa mengalami perubahan.
Takson lain juga berubah besar, tapi tidak berubah lebih baik. Sejumlah makhluk mengalami perubahan lingkungan dan adaptasinya tidak terlalu baik terhadap suasana yang baru. Kecocokan mereka terhubung dengan lingkungan, bukan perubahan. [Sumber]
9. Manusia Meledak di Udara
Mitos: Ketika tubuh dipaparkan dengan kehampaan ruang angkasa, tubuh manusia meledak
Mitos ini adalah hasil dari film-film fiksi ilmiah yang menggunakannya supaya memberi ketertarikan terhadap alur cerita. Faktanya, manusia dapat selamat 15 – 30 detik di luar angkasa apabila mereka menghembuskan napas sebelum terpapar hampa udara (ini mencegah paru-paru meledak dan mengirimkan udara ke pembuluh darah). Setelah 15 atau 30 detik, kekurangan oksigen menyebabkan ketidaksadaran diri yang membawa pada kematian karena kehabisan napas.
8. Bintang Paling Terang
Mitos: Polaris adalah bintang paling terang di langit malam belahan utara
Sirius sebenarnya lebih terang dengan magnitudo −1.47 bila dibandingkan dengan Polaris yaitu 1.97 (semakin rendah angkanya, semakin terang bintangnya). Pentingnya Polaris adalah bahwa posisinya di langit menandakan Utara – dan karena itu pula bintang ini dijuluki “Bintang Utara”. Polaris adalah bintang paling terang di konstelasi Ursa Minor dan merupakan Bintang Utara saat ini ketika bintang kutub berubah sepanjang waktu karena bintang menampakkan perpindahan berlanjutan yang lambat terhadap poros Bumi.
7. Aturan Lima Detik
Mitos: Makanan yang jatuh ke lantai dianggap aman dimakan bila diambil kembali dalam lima detik
Ini adalah omong kosong yang pastinya dikenal banyak orang. Bila ada kuman di lantai dan makanan mendarat di atasnya, otomatis mereka menempel ke makanan. Selain itu, memakan kuman dan kotoran tidak selalu menjadi hal buruk karena mereka membantu kita membangun sistem kekebalan tubuh yang kuat. Saya lebih memilih aturan “seberapa enak”: kalau makanannya sangat enak, saya bisa tinggalkan selama 10 menit, kemudian saya makan kembali.
6. Sisi Gelap Bulan
Mitos: Ada sisi tergelap dari bulan
Sebenarnya – setiap bagian dari bulan disinari pada suatu waktu oleh matahari. Kesalahpahaman ini muncul karena ada sisi tergelap bulan yang tak pernah tampak ke Bumi. Ini disebabkan oleh penguncian gelombang; hal ini dikarenakan bahwa tarikan gravitasi Bumi terhadap bulan sangat kuat sehingga bulan hanya menampakkan satu wajah ke kita. Wikipedia menyebutkan: “Penguncian gelombang terjadi ketika gradien gravitasi menyebabkan satu sisi tubuh astronomis selalu menghadap tubuh yang lain; contohnya, satu sisi Bulan selalu menghadap Bumi. Tubuh yang terkunci gelombang lama berotasi sebagaimana berevolusi terhadap Bumi. Rotasi ini menyebabkan satu belahan Bulan selalu menghadap Bumi.”
5. Sel Otak
Mitos: Sel otak tak dapat beregenerasi – bila Anda membunuh sebuah sel otak, maka sel itu tak bisa diganti
Alasan mitos ini menjadi semakin umum adalah karena mitos ini dipercayai dan diajarkan oleh komunitas ilmiah dalam jangka waktu yang lama. Tetapi pada tahun 1998, ilmuwan di Sweden and the Salk Institute di La Jolla, California menemukan bahwa sel otak pada manusia dapat beregenerasi. Sebelumnya lama dipercayai bahwa otak yang kompleks dapat terganggu oleh pertumbuhan sel baru, tapi studi menemukan bahwa memori dan pusat pembelajaran otak dapat menciptakan sel baru – memberikan harapan kepada penyembuhan penyakit seperti Alzheimer.
4. Koin dari Surga
Mitos: Sebuah koin yang dijatuhkan dari bangunan yang sangat tinggi dapat membunuh pejalan kaki di bawah
Mitos ini sangat umum sehingga menjadi cliche di sejumlah film. Mitosnya adalah bila Anda menjatuhkan koin dari puncak bangunan tinggi (seperti Empire State Building) – koin ini akan memperoleh kecepatan yang bisa membunuh seseorang bila mendarat di atas manusia di darat. Tapi faktanya adalah, aerodinamika sebuah koin tidak cukup untuk membuatnya berbahaya. Apa yang akan terjadi adalah orang yang terkena koin tersebut hanya merasa diketuk kepalanya – tentunya mereka selamat dari “bencana” tersebut.
3. Panas Akibat Gesekan
Mitos: Meteor menjadi panas karena gesekan ketika memasuki atmosfer
Ketika sebuah meteoroid memasuki atmosfer Bumi (menjadi meteor), sebenarnya kecepatan yang memadatkan udara di depan obyek yang menyebabkan obyek tersebut memanas. Adalah tekanan di udara yang mengakibatkan panas yang cukup untuk membuat batu tersebut sangat panas sehingga bersinar bila dilihat dari Bumi (bila kita beruntung melihatnya di langit pada waktu yang tepat). Kita juga perlu menolak mitos tentang meteor panas ketika tiba di Bumi – menjadi meteorit. Meteorit selalu dingin ketika tiba di daratan – dan faktanya sering ditemukan terlapisi es. Ini dikarenakan batu tersebut sangat dingin dari perjalanannya melintasi ruang angkasa sehingga panas ketika masuk ke Bumi belum cukup untuk membakar lapisan terluarnya.
2. Petir
Mitos: Petir tak pernah menyambar tempat yang sama dua kali
Lain kali jika Anda melihat sambaran petir dan Anda beranggapan untuk lari ke tempat sambaran untuk melindungi diri dari serangan selanjutnya, ingatlah ini! Petir memang menyambar tempat yang sama dua kali – malahan, ini sangat umum. Petir lebih memilih tempat-tempat tertentu seperti pohon tinggi atau bangunan. Di lapangan luas, obyek yang paling tinggi memiliki kemungkinan besar disambar beberapa kali hingga petir berpindah jauh untuk mencari target baru. Empire State Building tersambar petir 25 kali setahun.
1. Gravitasi di Luar Angkasa
Mitos: Tidak ada gravitasi di luar angkasa
Faktanya, ada gravitasi di luar angkasa – sangat banyak. Alasan bahwa astronot tampak tak ada beban adalah karena mereka mengorbit Bumi. Mereka jatuh ke Bumi tapi bergerak ke samping untuk menghindarinya. Jadi, mereka selalu jatuh tapi tak pernah mendarat. Gravitasi memang ada di seluruh luar angkasa secara virtual (ada tapi tak dapat dirasakan). Ketika sebuah pesawat ulang alik mencapai ketinggian orbit (Sekitar 250 mil di atas permukaan Bumi), gravitasi hanya berkurang 10%.
Sumber tulisan: listverse.com – Top 10 Ridiculously Common Science Myths
There is nothing better than a bit of mythbusting (which accounts for the popularity of the television program of the same name), so here we are again, presenting you with a new list of terribly common misconceptions and myths – this time about science.
The Myth: Evolution causes something to go from “lower” to “higher”
While it is a fact that natural selection weeds out unhealthy genes from the gene pool, there are many cases where an imperfect organism has survived. Some examples of this are fungi, sharks, crayfish, and mosses – these have all remained essentially the same over a great period of time. These organisms are all sufficiently adapted to their environment to survive without improvement.
Other taxa have changed a lot, but not necessarily for the better. Some creatures have had their environments changed and their adaptations may not be as well suited to their new situation. Fitness is linked to their environment, not to progress. [Source]
The Myth: When exposed to the vacuum of space, the human body pops
This myth is the result of science fiction movies which use it to add excitement or drama to the plot. In fact, a human can survive for 15 – 30 seconds in outer space as long as they breathe out before the exposure (this prevents the lungs from bursting and sending air into the bloodstream). After 15 or so seconds, the lack of oxygen causes unconsciousness which eventually leads to death by asphyxiation.
The Myth: Polaris is the brightest star in the northern hemisphere night sky
Sirius is actually brighter with a magnitude of −1.47 compared to Polaris’ 1.97 (the lower the number the brighter the star). The importance of Polaris is that its position in the sky marks North – and for that reason it is also called the “North Star”. Polaris is the brightest star in the constellation Ursa Minor and, interestingly, is only the current North Star as pole stars change over time because stars exhibit a slow continuous drift with respect to the Earth’s axis.
The Myth: Food that drops on the floor is safe to eat if you pick it up within five seconds
This is utter bunkum which should be obvious to most readers. If there are germs on the floor and the food lands on them, they will immediately stick to the food. Having said that, eating germs and dirt is not always a bad thing as it helps us to develop a robust immune system. I prefer to have a “how-tasty-is-it” rule: if it is something really tasty, it can sit there for ten minutes for all I care – I will still eat it.
The Myth: There is a dark side of the moon
Actually – every part of the moon is illuminated at sometime by the sun. This misconception has come about because there is a side of the moon which is never visible to the earth. This is due to tidal locking; this is due to the fact that Earth’s gravitational pull on the moon is so immense that it can only show one face to us. Wikipedia puts it rather smartly thus: “Tidal locking occurs when the gravitational gradient makes one side of an astronomical body always face another; for example, one side of the Earth’s Moon always faces the Earth. A tidally locked body takes just as long to rotate around its own axis as it does to revolve around its partner. This synchronous rotation causes one hemisphere constantly to face the partner body.”
The Myth: Brain cells can’t regenerate – if you kill a brain cell, it is never replaced
The reason for this myth being so common is that it was believed and taught by the science community for a very long time. But in 1998, scientists at the Sweden and the Salk Institute in La Jolla, California discovered that brain cells in mature humans can regenerate. It had previously been long believed that complex brains would be severely disrupted by new cell growth, but the study found that the memory and learning center of the brain can create new cells – giving hope for an eventual cure for illnesses like Alzheimer’s.
The Myth: A penny dropped from a very high building can kill a pedestrian below
This myth is so common it has even become a bit of a cliche in movies. The idea is that if you drop a penny from the top of a tall building (such as the Empire State Building) – it will pick up enough speed to kill a person if it lands on them on the ground. But the fact is, the aerodynamics of a penny are not sufficient to make it dangerous. What would happen in reality is that the person who gets hit would feel a sting – but they would certainly survive the impact.
The Myth: Meteors are heated by friction when entering the atmosphere
When a meteoroid enters the atmosphere of the earth (becoming a meteor), it is actually the speed compressing the air in front of the object that causes it to heat up. It is the pressure on the air that generates a heat intense enough to make the rock so hot that is glows brilliantly for our viewing pleasure (if we are lucky enough to be looking in the sky at the right time). We should also dispel the myth about meteors being hot when they hit the earth – becoming meteorites. Meteorites are almost always cold when they hit – and in fact they are often found covered in frost. This is because they are so cold from their journey through space that the entry heat is not sufficient to do more than burn off the outer layers.
The Myth: Lightning never strikes the same place twice
Next time you see lightning strike and you consider running to the spot to protect yourself from the next bolt, remember this item! Lightning does strike the same place twice – in fact it is very common. Lightning obviously favors certain areas such as high trees or buildings. In a large field, the tallest object is likely to be struck multiple times until the lightning moves sufficiently far away to find a new target. The Empire State Building gets struck around 25 times a year.
The Myth: There is no gravity in space
In fact, there is gravity in space – a lot of it. The reason that astronauts appear to be weightless because they are orbiting the earth. They are falling towards the earth but moving sufficiently sideways to miss it. So they are basically always falling but never landing. Gravity exists in virtually all areas of space. When a shuttle reaches orbit height (around 250 miles above the earth), gravity is reduced by only 10%.
10
Evolutionary Improvements
The Myth: Evolution causes something to go from “lower” to “higher”
While it is a fact that natural selection weeds out unhealthy genes from the gene pool, there are many cases where an imperfect organism has survived. Some examples of this are fungi, sharks, crayfish, and mosses – these have all remained essentially the same over a great period of time. These organisms are all sufficiently adapted to their environment to survive without improvement.
Other taxa have changed a lot, but not necessarily for the better. Some creatures have had their environments changed and their adaptations may not be as well suited to their new situation. Fitness is linked to their environment, not to progress. [Source]
9
Humans Pop In Space
The Myth: When exposed to the vacuum of space, the human body pops
This myth is the result of science fiction movies which use it to add excitement or drama to the plot. In fact, a human can survive for 15 – 30 seconds in outer space as long as they breathe out before the exposure (this prevents the lungs from bursting and sending air into the bloodstream). After 15 or so seconds, the lack of oxygen causes unconsciousness which eventually leads to death by asphyxiation.
8
Brightest Star
The Myth: Polaris is the brightest star in the northern hemisphere night sky
Sirius is actually brighter with a magnitude of −1.47 compared to Polaris’ 1.97 (the lower the number the brighter the star). The importance of Polaris is that its position in the sky marks North – and for that reason it is also called the “North Star”. Polaris is the brightest star in the constellation Ursa Minor and, interestingly, is only the current North Star as pole stars change over time because stars exhibit a slow continuous drift with respect to the Earth’s axis.
7
Five Second Rule
The Myth: Food that drops on the floor is safe to eat if you pick it up within five seconds
This is utter bunkum which should be obvious to most readers. If there are germs on the floor and the food lands on them, they will immediately stick to the food. Having said that, eating germs and dirt is not always a bad thing as it helps us to develop a robust immune system. I prefer to have a “how-tasty-is-it” rule: if it is something really tasty, it can sit there for ten minutes for all I care – I will still eat it.
6
Dark side of the Moon
The Myth: There is a dark side of the moon
Actually – every part of the moon is illuminated at sometime by the sun. This misconception has come about because there is a side of the moon which is never visible to the earth. This is due to tidal locking; this is due to the fact that Earth’s gravitational pull on the moon is so immense that it can only show one face to us. Wikipedia puts it rather smartly thus: “Tidal locking occurs when the gravitational gradient makes one side of an astronomical body always face another; for example, one side of the Earth’s Moon always faces the Earth. A tidally locked body takes just as long to rotate around its own axis as it does to revolve around its partner. This synchronous rotation causes one hemisphere constantly to face the partner body.”
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5
Brain Cells
The Myth: Brain cells can’t regenerate – if you kill a brain cell, it is never replaced
The reason for this myth being so common is that it was believed and taught by the science community for a very long time. But in 1998, scientists at the Sweden and the Salk Institute in La Jolla, California discovered that brain cells in mature humans can regenerate. It had previously been long believed that complex brains would be severely disrupted by new cell growth, but the study found that the memory and learning center of the brain can create new cells – giving hope for an eventual cure for illnesses like Alzheimer’s.
4
Pennies from Heaven
The Myth: A penny dropped from a very high building can kill a pedestrian below
This myth is so common it has even become a bit of a cliche in movies. The idea is that if you drop a penny from the top of a tall building (such as the Empire State Building) – it will pick up enough speed to kill a person if it lands on them on the ground. But the fact is, the aerodynamics of a penny are not sufficient to make it dangerous. What would happen in reality is that the person who gets hit would feel a sting – but they would certainly survive the impact.
3
Friction Heat
The Myth: Meteors are heated by friction when entering the atmosphere
When a meteoroid enters the atmosphere of the earth (becoming a meteor), it is actually the speed compressing the air in front of the object that causes it to heat up. It is the pressure on the air that generates a heat intense enough to make the rock so hot that is glows brilliantly for our viewing pleasure (if we are lucky enough to be looking in the sky at the right time). We should also dispel the myth about meteors being hot when they hit the earth – becoming meteorites. Meteorites are almost always cold when they hit – and in fact they are often found covered in frost. This is because they are so cold from their journey through space that the entry heat is not sufficient to do more than burn off the outer layers.
2
Lightning
The Myth: Lightning never strikes the same place twice
Next time you see lightning strike and you consider running to the spot to protect yourself from the next bolt, remember this item! Lightning does strike the same place twice – in fact it is very common. Lightning obviously favors certain areas such as high trees or buildings. In a large field, the tallest object is likely to be struck multiple times until the lightning moves sufficiently far away to find a new target. The Empire State Building gets struck around 25 times a year.
1
Gravity in Space
The Myth: There is no gravity in space
In fact, there is gravity in space – a lot of it. The reason that astronauts appear to be weightless because they are orbiting the earth. They are falling towards the earth but moving sufficiently sideways to miss it. So they are basically always falling but never landing. Gravity exists in virtually all areas of space. When a shuttle reaches orbit height (around 250 miles above the earth), gravity is reduced by only 10%.
10 Penjara Terburuk di Dunia
Contoh akibat dari kekerasan yang terjadi di dalam lingkungan penjara.
Penikaman, pembunuhan, kekejaman, pemerkosaan geng dan sejumlah horor lainnya disiarkan secara meluas oleh orang-orang yang telah menghabiskan waktu di dalam penjara. Tentunya, semua itu bukan kisah penjara yang dibuat-buat, karena Anda belum sering mendengar mengenai penjara seperti itu yang belum ada perubahan dari tahun ke tahun, tapi namanya akan tetap muncul sepanjang masa.
Penjara tertentu, tua dan baru, terkenal karena kekejaman dan dengan mudahnya membuat kisah horor itu menjadi kenyataan. Berikut adalah daftar 10 penjara terburuk di dunia.
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