Hebrews 1:3 does say the Son of God is the effulgence of God's glory and the impress of His substance.
What else does the writer say? The writer totally identifies the Son of God with Jehovah the Creator in absolute terms in verses 8 - 12.
But of the Son, "Your throne, O God, is forever and ever, and the scepter of uprighteness is the scepter of Your kingdom." (v.8)
It is clear enough that the
Son is God[/b] there. But then the writer applies
Psalm 102:25-27 to the Son of God !
"You have loved righteousness and hated lawlessness; therefore God, Your God has anointed You with the oil of exultant joy above your partner;"
And, "You in the beginning, Lord, laid the foundation of the earth, and the heavens are the works of Your hands;
They will perish, but You remain perpetually; and they all will become old like a garment, And like a mantle You will roll them up; like a garment they will also be changed; but You are the same, and Your years will not faith." (Hebrews 1:9-12)
To highlight how emphatically
Psalm 102 is being used to apply to the Son of God as Jehovah God, I will include some portions of the Psalm.
From
Psalm 102 of 28 verses.
Verse 1 - "O
Jehovah, hear my prayer; And let my cry come unto You."
Verse 12 - "But You, O
Jehovah, abide forever; and Your memorial is from generation to generation."
Verse 16 - "For
Jehovah has built Zion; He has appeared in His glory."
Verse 19 - For He has looked down from the height of His sanctuary; From heaven
Jehovah beheld the earth."
Verse 21 - "That the name of
Jehovah may be declared in Zion, and His praise in Jerusalem."
Verse 22 - "When the peoples are gathered together, and the kingdoms, to serve
Jehovah."
Now verses 24 through the end, verse 28.
"I said, My God, Do not take me away in the middle of my days;
Your years are throughout all generations.
Of old You laid the foundation of the earth,
And the heavens are the work of Your hands.
They will perish, but You endure;
Indeed all of them will wear out like a garment;
Like clothing You will change them,
And they will be changed.
But You are the same,
And Your years are without end.
The children of Your servants will continue.
and their seed will be established before You."
There is no possibility of arguing against that the One who is the effulgence of God's glory is also God. The writer of
Hebrews chapter one understood the Son of God to be Jehovah of
Psalm 102 the eternal Creator and King of Israel.