Name: 哈佛科學家為何認為這個物體是外星飛船？ (Why Harvard Scientists Think This Object Is An Alien Spacecraft)
Uploaded: 2021-01-14T11:18:54.000Z
Duration: 5 min 29 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

Narrator: We have a mysterious new kid on the block.

情態副詞

Oumuamua is the first interstellar object

it has raised more questions than it answers.

And yes, even the ultimate query, is it aliens?

That's what two Harvard astrophysicists posed

suggesting that Oumuamua could be some type

the idea didn't sound as far-fetched as you might think.

Loeb: I prefer to adopt the maxim of Sherlock Holmes

whatever remains, as improbable as it is,

is that aliens are always the least likely answer.

But here's the thing, the more reasonable explanation

is probably a stray comet from another stellar system.

The only problem is that it doesn't look like any comet

because it appears to lack that iconic tail.

Loeb: There was an anomaly seen in the data.

which in this case is a cometary outgassing.

And so we propose an alternative interpretation

Narrator: But it seems extreme to assume aliens

just because Oumuamua doesn't look like a comet, right?

Not when the Harvard scientists accounted

As Oumuamua traveled through our solar system,

it didn't follow the normal path of a typical comet

which couldn't be explained by gravity alone.

Something else, some unknown force was also at play,

Loeb: I cannot think of any other possibility

other than the outgassing that we find in comets,

There is no other proposal on the table right now.

So too can sunlight push against a spacecraft

Incidentally, we call these spacecraft solar sails.

Pressure from sunlight is extremely light.

Lighter than the weight of a fly on your hand.

Which means in order for it to be effective,

solar sails also have to be extremely light and thin.

In 2010, for example, Japan's space agency

But it eventually managed to travel over 65 million miles

And it's this type of force that the Harvard scientists

Of course, that's if it's an alien made sail

Loeb: Well first of all, I am not confident

I would highly recommend people to read the paper.

If they have a better idea, they should publish it.

Narrator: And as always, not everyone agrees

I think it's in contrast with what the data says.

You know, we did consider that possibility

in our own paper, which was published earlier,

and we dismissed it as not being physically valid.

You know again, there's no reason to think Oumuamua

Weryk: So we think Oumuamua still has ice

and the sublimating ice gives it a small tiny kick

And so we just don't see that from the ground.

Narrator: And yes, in all probability, he's right.