Quantidades, distâncias, vida no Universo e visitantes

Muitas pessoas, principalmente durante a visita escolar ao Planetário, me perguntam sobre vida fora da Terra, ou, como eles dizem, ETs. Eu costumo responder fazendo uma análise sobre algumas condições do Universo e deixando a conclusão para a própria pessoa.

Bom, vamos ponderar sobre este assunto um pouquinho aqui também. Costumo começar analisando o céu durante a noite. Excluindo três galáxias (Andrômeda, a Pequena e a Grande Nuvem de Magalhães), tudo o que observamos a olho nu pertence a nossa galáxia, a Via Láctea. Numa noite limpa em um lugar sem poluição luminosa, podemos ver até 6.000 astros. Esse número de estrelas, que parece grande, não é nada se compararmos com a estimativa da galáxia inteira que é de 200 bilhões de estrelas!

Saindo da nossa galáxia, encontramos outras galáxias e as estimativas nos dizem que podem existir outros 200 bilhões de galáxias no Universo! Algumas com até trilhões de estrelas. Chegamos à conclusão, então, de que no Universo existem muitas estrelas!

Com o desenvolvimento de telescópios mais modernos e ultrassensíveis, estamos descobrindo muitos planetas ao redor de estrelas. Este número já está em 488 planetas ao redor de outras estrelas (até a data desta postagem). E só estamos falando de estrelas relativamente próximas do nosso Sistema Solar. O que parecia exceção, agora parece regra: planetas orbitando estrelas.

Conhecendo esses dados, não é difícil de se acreditar que exista algum planeta, dessas aparentemente infinitas estrelas, que apresente condições para a vida se desenvolver. Mesmo tendo a Terra características muito específicas e peculiares para isso acontecer.
Agora, a meu ver, ter vida em outro lugar não significa que alguém ou alguma coisa já tenha vindo até a Terra e nem que ela seja tão desenvolvida e complexa como os seres humanos. Explico meu ponto de vista: os números não são grandes apenas para a quantidade de estrelas e galáxias, mas também são enormes para as distâncias.

O local mais distante em que o homem pôs os pés fora da Terra foi a Lua, que está a mais ou menos 380 mil quilômetros. O Sol já se encontra a uma distância considerável, 150 milhões de quilômetros.
Considerável para os nossos padrões, mas se formos comparar com a estrela mais próxima do Sistema Solar, a Alfa do Centauro (na verdade, um sistema com três estrelas), a distância Sol-Terra se torna insignificante, são 4,4 anos-luz, ou seja, quase 44 trilhões de quilômetros!

Do centro da nossa galáxia estamos distantes aproximadamente 26 mil anos-luz (em quilômetros já fica impossível, por favor). E a nossa galáxia inteira tem 100 mil anos-luz de diâmetro.
Saindo da nossa galáxia, temos a galáxia de Andrômeda, por exemplo, como uma das “vizinhas” mais próximas, dois milhões de anos-luz. E aí, vale a pena parar para refletir. A luz das estrelas dessa galáxia (visível a olho nu, diga-se de passagem) demora dois milhões de anos para chegar até a Terra! A velocidade da luz é de 300 mil km/s! E nós sabemos, pelas Leis da Física, que nada pode viajar acima desta velocidade. (Nem falar das galáxias mais distantes: 12 bilhões de anos-luz.)

É aí que eu acho que viajantes espaciais são tão impotentes como nós, mesmo se forem mais evoluídos. Como percorrer todas essas distâncias tendo as Leis da Física vigorando em todos os lugares no Universo? Mesmo viajando próximo da velocidade da luz, demoraríamos muito de uma estrela a outra. Até existem algumas teorias que dizem ser possível viajar de um ponto a outro no Universo rapidamente, como as que falam dos “buracos de minhoca”, mas mesmo assim nada leva a crer que alguém resistiria a uma viagem dessas. Além deste ponto, estaríamos no ramo da ficção científica.

Apesar de alguns relatos de aparecimentos de OVNIs, não acredito que a única explicação seja a de serem seres extraterrestes e, mesmo assim, realizarem uma viagem desta magnitude para chupar uma cabra no interior de sei lá onde. Deve haver coisas mais interessantes que isso depois de uma viagem dessas. Brincadeiras à parte, estamos vivendo em uma época em que quase todo mundo tem um máquina digital em casa ou no bolso, e não vemos mais tantos relatos de OVNIs como antigamente.
A verdade deve estar lá fora mesmo, só que longe pra caramba!  

He http://www.examdumpsview.com/ stood there for a long time. Tami Joan and John desperately retreated until they reached the other side of the door, holding two sweaty bodies tightly together. The drivers hand bent into the shape of a cup, blocking the lights shone on the street light, looked at them more carefully. Suddenly, a loud noise echoed in the air. Tameron could not help but constricted a while, and John made a short, screaming scream. Behind the driver, the air in the distance was filled with bright red and blue flame stripes instantly. Then again is a few roar and scream. The driver turns and looks up, just to see a huge, examdumpsview orange-red cobweb over the city. It was a fireworks, and Tamie remembered the news read in the newspaper. It is a gift from the host and the Secretary-General of the United Nations to the delegates attending the conference and welcomes them to this great city on Earth. The driver turned toward the taxi again. Pat soon, he opened the door lock, slowly opened the door. 2 As usual, the informant did not leave a name. Therefore, there is no other way to pour back into the past to understand what the reporter said is a piece of open space. The headquarters radio said He said it was on the 37th Street near Eleventh Street. Those at the Notification Center never figured out where the exact location of the murder was. Although it is nine oclock in the morning, it has made people sweat more than hot. Emilia Shakes lay aside a tall grass thatch. She is conducting a search of light – a jargon of crime scene investigators – searching for suspicious objects with an S-shaped route. Nothing at all She looked down at the intercom on the dark blue uniform shirt. Patrolman 5885 calls headquarters without any notice. Do you have any further news The dispatcher replied in a bumpy noise 5885, there is no more information about the scene of the crime cissp pdf at the moment, but one thing The informant said he hoped the victim was dead. Please say it again, headquarters. The complainant said he hoped the victim was already dead. He said it would be best if so. Finished. Hopefully the victim Dead Shakes struggled across a broken barbed wire and began searching for another piece of open space. Still not found. She wants to leave. Just call 10-90, report that without any discovery, you can return to the Si Si area, it is her daily patrol area. Her knees hurt and she felt 400-101 questions as if she had been roasted on a terrible August day. She just wanted to slip to the Port Authority and get stuck with the Little Furrier there and come back to a large can of Arizona iced tea. Then, at eleven thirty – just two hours now – she was able to clear the drawers in the south section of Midtown and go to the lower town for training. But she finally did not do this. She can not leave this briefing without answering the phone call. As she continued to move on, she walked along the hot sidewalk through the path between the two abandoned apartments and into another covered, planted area. She slid her slender forefinger down into her flat-top hat and scratched it with irresistible restraints through layers of long, red hair on her head. In order to scratch more scalp, she simply faded her cap side, while crazy scratch. Sweat streaming down her forehead, itchy, so she fiercely blew a few brows.

This place is really messy. Lyme does not like the mess when cleaning the room. Microsoft exam He does not like the kind of chaos and roar, can not stand the harsh vacuum cleaner – he found himself particularly annoyed that stuff. 400-101 questions He was satisfied with it, satisfied with what it is now. This room, which he calls the office, is located on the second floor of this gothic, Upper West Side apartment overlooking the Central Park. The room was large, twenty by twenty feet square, but almost every inch of space was full of things. Sometimes he closes his eyes and plays a game trying to discern the scent of different objects in the room thousands of books and magazines, piles of copy paper, hot TV transistors, dusty light bulbs, Bulletin boards made of cork, as well as different upholstery materials such as vinyl, hydrogen peroxide and latex. He can distinguish three different brands of Scotch whiskey. And pest guano taste. I do not want to see him and tell http://www.examdumpsview.com/ him Im very busy. Theres another young police officer, Ernie Banks, who is the same name as a professional baseball player, right You really should have me clean the room. Every time you wait until someone visits you, you will find out how dirty it is here. Visiting God, the word sounds really old, at least in Victorian terms. Far too far .– So to say, there will be a bad ceremony Dirty What Thomas said is room, but Lyme thinks he also includes himself as an employer. Lymes hair Microsoft exam is dark and dense, like a twenty-year-old – though he is twice as old. However, they are entangled in a muddle-headdresses, grooming needs to be trimmed. Black beard on his face has not scratched three days, looks dirty. He often woke up from his sleep because of itchy ears, indicating that the hair there should be repaired. Lymes nails are long, fingernails and toenails are the same the ugly scary pajamas on his body have been worn continuously for a week without a change. His eyes were slender, his eyes dark brown, and his face looked rather pretty – I do not know if it was a big deal or something else, and Blaine told him more than once. They want to talk to you, continued Thomas. They said it was very important. Well, let them know. You have not seen Leon for nearly a year. Why See him now Did you scare the bird If you scared the bird, beware I was in a hurry with you. Its very important, Lincoln. Very important, I remember what you just said. He had Cisco exam called earlier, cissp pdf I had a nap, and you were out again. You woke up until six in the morning. No, he paused. Yes, I woke up very early, but then I fell asleep again and slept well. Did you check your message Thomas said There was no talk of him. He said he would It was around 10 oclock. Its just past eleven, and maybe hes temporarily called out of the examdumpsview emergency room, for a while. What do you want to say Did you just call . Maybe he wants to call in, and you just take up the line. I just What did I say Lyme asked, See youre angry, Im not saying you can not call. You Of course its always possible, I just said he might make a phone call, and you just take the Cisco exam line. No, you mean, this morning, fucking everything is not pleasing to the eye. You know, theres one thing called call waiting, you can pick up two calls at a time.We should have applied for one.My old friend Leon wants to do.His professional baseball player friend wants Ask them. Ask me now.